Healthcare Liquid Filtration Guide

GVS would like to share some basic concepts about filtration with you. The following clarifies some key aspects of filtration technology applied to the specific applications. Our Sales Engineers are always at your disposal for any further explanation. The following properties should be considered at the time of selecting the proper filter media for your application.

Screen or Mesh Filtration

Filtration through a mesh means that the screen will stop particles larger than the mesh size rating. Medical meshes adopted by GVS are medical grade and comply with the very strict international requirements for cleanliness. The screens are composed of monofilaments. Standard material is polyamide (PA6.6) or polyester (PE). Filtration through a mesh is mechanical filtration. Mesh does not have the ability to stop air, except in special situations. Mesh is specified by its mesh size, which is just one of the several key characteristics.

Note: Some of our filters are manufactured with different media instead of mesh. We use many hydrophobic and hydrophilic membranes, wich are normally dedicated to very special applications. You can find these in our catalog.

Mesh characteristics
The mesh used by GVS for our medical filter products is manufactured with uniform weave and accurate open-mesh structure which guarantees the lowest possible flow restriction. The "windows" of the mesh normally have a square shape.

- Raw materials used for the monofilament are polyamide (PA6.6) or polyester (PE). Other raw materials are available but not very popular.

- Mesh opening (micron): this is the size of any window or opening. The openings are tested by electronic analysis image systems during production.

- Open area: this is a percentage (%) of the total mesh area which is "open" to let the flow go through. It's important to have high open area percentage to reduce flow restriction. This is also tested by electronic analysis image systems during production.

- Mesh count: this is the quantity of threads per cm or per inch (n/cm) or (n/in).

- Thread diameter (micron) this is the diameter of the filament. It is also tested by electronic analysis image systems during production.

- Weight of the mesh (g/m2) or (oz/yd2), important to qualify the quality of the mesh.

- Thickness of the mesh. Thickness is expressed in microns (µm) and its stability is very important to achieve the proper handling of the mesh during production.

Mesh used by GVS have efficiency which is always higher than that of international standards.

Sterilization Stability
This characteristic allows proper performance at elevated temperatures. The mesh used in GVS filters is usually compatible with any of the current sterilization methods: EtO, e-beam radiation, or steam sterilization with no adverse affects.

Biosafety
These tests are conducted in compliance with ISO-10993 and USP Class VI. Tests conducted are:
Cytotoxicity
Sensitization
Irritation or Intracutanous Reactivity
Systemic Toxicity (Acute)
Hemocompatibility (Hemolysis)

Pyrogenicity
Pyrogens are chemicals on the filter media and other components that are caused by the waste of dead bacteria. When introduced to a patient, they can elevate the patient's temperature, and can cause complications - even death. Filters that are pyrogenic can make solutions pyrogenic. They cannot be removed by sterilization, so it is very important that non-pyrogenic filter media and components are used in the production of medical filter devices. The test to determine the pyrogenicity is the LAL test (Limulus Amebocyte Lysate test).

Extractables
Extractables are contaminants (typically chemicals) that elute from filters which might affect quality of the effluent. Wetting agents (surfactants) or manufacturing or sterilization residuals are the main cause of undesired extractables. Typical problems caused by extractables are found in the following applications:

- HPLC analysis (strange result)

- Cell culture (cytotoxicity)

- Microbiological analysis (affects the microorganism)

- Environmental analysis (contaminants)

Flushing of the line prior to use can reduce Extractables and their adverse effects. 
The amount of extractables allowed for mesh filters are described in following regulations:
21CFR177.1500 (PA)
21CFR177.1630 (PE)

Filter Efficiency (FE)
This is the quantity of particulate retained compared to the total quantity of particulate to which the filter is challenged. It is expressed in % and refers to a specific size of particles.

Effective Filtration Area (EFA)
This is the actual filtration area in a device that is subject to filtration. For instance, in a tubular filter, the frame (socket, two ribs and top cover) made by plastics should be eliminated from the calculations of the device EFA. In mesh filters you should only eliminate the seal area.

 

Membrane information

Filtration through a membrane means that the filter material will stop particles larger than the pore size rating. This enables an absolute pore size rating for the membranes for which they are clearly classified. Bacterial retention claims can be made based on the pore size of the membrane.

Hydrophilic – Hydrophobic Membranes Hydrophilic membranes have permeability of aqueous solutions and once wetted, they stop gasses. This means that aqueous solutions pass through hydrophilic membranes but gas is stopped when the membrane is wet until the applied pressure exceeds the "bubble point", at which time the air will evacuate the pore, the liquid is expelled, and the gas will go through. Dry hydrophilic membrane allows gas to pass through. Our HI-FLO PES membranes are hydrophilic membranes.

Hydrophobic membranes have permeability to the gas, but they stop aqueous solutions. In other words, they do the opposite job when compared to hydrophilic membranes. This means that gas will pass through these membranes, but aqueous solutions will be stopped. If air or gas can reach the hydrophobic membrane, it will go through, but if the contact with the hydrophobic membrane is not possible, then the gas will not pass through. The pressure at which aqueous solutions will pass through a hydrophobic membrane is called the water breakthrough (WBT) or water intrusion pressure (WIP). PTFE membranes are hydrophobic membranes. PES membranes are hydrophilic membranes.

Pore size
Pore size is determined by the size of the particle that is expected to be retained with a defined with a high degree of efficiency. Pore size is typically stated in micrometers or microns (μm), and should clearly be designated as either nominal or absolute. Nominal pore size is the ability to retain a majority (60% - 98%) of particles having a specific dimension. Retention efficiency is also depending on such process conditions as concentration, operating pressure etc. Rating parameters can vary among manufacturers. When the pore size, or retention, is "nominal", it should be stated at a particle size and a percent, i.e., 99.97% retention of 0.3 μm particles. Absolute pore size is the ability to retain the 100% of particles of a specific dimension under defined test conditions (particle size, challenge pressure, concentration, detection method).

Pore Size Challenge Organism

• 0.1 micron Acholeplasma laidlawii
• 0.2 micron Brevundimonas diminuta
• 0.45 micron Serratia marcescens
• 0.8 micron Lactobacillus species
• 1.2 micron Candida albicans

The above table shows proper pore size of hydrophilic membranes to be used to retain the corresponding bacteria. Hydrophobic membranes are about ten times more efficient in retaining bacteria in air than they are in liquids using the same pore size.

Chemical compatibility
This is the ability of the membrane to resist to chemicals without mechanical or chemical damage from chemical exposure. Information about the liquid used with a specific filter material should be outlined before application to determine compatibility, GVS can assist customers in choosing the proper filter (and housing) materials.

Extractables
Extractables are contaminants (typically chemicals) that elute from the filter which might affect quality of the effluent. Wetting agents (surfactants), manufacturing or sterilization residuals are the main cause of undesired extractables. Typical problems caused by extractables are found in the following applications:

• HPLC analysis (strange result)
• Cell culture (cytotoxicity)
• Microbiological analysis (affects the microorganism)
• Environmental analysis (contaminants)

Flushing of the line prior to use can reduce Extractables and their adverse effects.

Binding
This is the property of substances to be filtered having affinity with membra nes. This could be a positive effect in some circumstances, but most of the time it can create adverse effects. Particularly it could lead to loss of active components of the liquid to be filtered reducing its beneficial effect. Our PES HI-FLO membrane is low protein binding.

Thermal Stability
This characteristic allows unchanged performance at elevated temperatures. Some membranes can only be sterilized by EtO. Others can be gamma, beta or e-beam sterilized, as well as EtO. Others can be also steam sterilized with no adverse affects. Membrane performance is sometimes reduced at temperature higher than 25°C, and high temperatures can also reduce chemical stability. PTFE membrane is widely stable (any type of sterilization) if the product is designed properly. PES membrane is suggested for EtO and irradiation (no steam sterilization).

Biosafety
These tests are conducted in compliance with ISO-10993 and USP class VI, see specifications Tests that are conducted are:

• Cytotoxicity
• Sensitization
• Irritation intracutaneous reactivity
• Systemic toxicity (acute)
• Hemocompatibility (Hemolysis)

Pyrogenicity
Pyrogens are chemicals on the filter media and other components that are caused by the waste of dead bacteria. When introduced to a patient, they can elevate the patient's temperature, and can cause complications – even death. Filters that are pyrogenic can make solutions pyrogenic. They cannot be removed by sterilization, so it is very important that non-pyrogenic filter media and components are used in the production of medical filter devices. The test to determine the pyrogenicity is the LAL test (Limulus Amebocyte Lysate test).

Bubble Point (BP)
Typically this test that is performed on hydrophilic membranes. The BP pressure is the pressure to force air through a wetted hydrophilic membrane. These tests are typically performed with water; however, this test can be conducted on hydrophilic membranes using liquids other than water that will wet the membrane. The BP is an indication of the membrane pore size, as related to actual bacterial retention. This test can also be performed on hydrophobic membranes if the correct solvent (instead of aqueous solution) is used, and is compatible with the entire product.

Water Breakthrough (WBT)
This is the test performed on hydrophobic membranes, and it is also related to the pore size of the membrane. The WBT pressure (sometimes referred to as water intrusion pressure) is the pressure it takes to force an aqueous solution through a hydrophobic membrane.

Water Flow Rate (WFR)
Typically this test is performed on hydrophilic membranes. The WFR has the aim to measure the flow of a liquid through a wetted hydrophilic membrane, at a fixed test pressure and time. This test is typically performed with water; however, it can be performed with other solutions, as long as the filter media is compatible with the liquid.

Air Flow (AF)
This is a flow rate typically related to hydrophobic membranes. It is the amount of air that passes through a fixed surface of membrane with a specific applied pressure.

Filter Efficiency (FE)
Quantity of particulate or bacteria retained compared to the total quantity of particulate or bacteria to which the filter is challenged. It is expressed in % and referred to a specific size of particles.

Effective Filtration Area (EFA)
This is the actual filtration area in a device that is subject to filtration. For instance, whereas a 25 mm device may start out with a disc of filter media that is cut to 25 mm, the sealing surfaces should be eliminated from the calculations of the device EFA.

Main membranes used are:

Cellulose Acetate (CA)
Hydrophilic membrane. Low protein binding , (reducing filter changes when filtering proteinaceous solutions?). Ideal for protein , cell culture media and enzymes filtrations, tissue culture media sterilization, biological fluid filtration and other filtration applications where maximum recovery of proteins is critical.

Nylon (NY)
Hydrophilic membrane. Ideal for use in general filtration or medical assays. Superior strength, resistant to a range of organic solvents. Low extractables. High protein binding capacity. Lot-to-lot consistency.

Polyethersulfone (PES)
Hydrophilic membrane. designed to remove particulates during general filtration, low protein and drug binding characteristics make itideally suited for use in life science applications. Its strength and durability are advantageous during usage that involves aggressive handling or automated equipment. Low protein and drug binding characteristics maximize recovery of critical drugs used in I.V. therapy, chemotherapy and open-heart surgery.

Nitrocellulose Mixed Esters (MCE)
Hydrophilic membrane. Aqueous clarification and particulate capture. Consistent high flow rate for faster filtration. Uniform pore structure for selectivity. Hydrophilic, inert cellulose nitrate. High binding capacity. Manufactured thickness within 10 microns.

Polyvinylidene Difluoride (PVDF)
Hydrophilic membrane. Ideal for use in Sterilizing and Clarifying filtration of biological solutions. High Flow Rates. Low Extractables. Broad Chemical Compatibility.Very low protein binding.

Polytetrafluoroethylene (PTFE)
Hydrophobic membrane. Ideal for filtration of strong acids and aggressive solutions, venting applications, phase separations, aerosol samplings. Chemically and biologically inert. Superior chemical resistance. Can withstand high temperatures.

Glass Fiber (GF)
Hydrophilic material. Used also as a pre-filter to extend membrane life. Eliminate sample contamination. Excellent wet strength for each handling and filter integrity. Ideal for water/air pollution analysis, liquid clarification and cell harvesting.

Regenerated Cellulose (RC)
Hydrophilic membrane. Resistant to a very wide range of solvents. Suitable for use with either aqueous solutions or organic solvents. Compatible with HPLC solvents. Very low protein binding capacity and hence excellent for protein recovery applications.

Polymers information

Thermoplastics and thermosets are the two basic groups of plastic materials. Thermoplastic resins can be repeatedly melted and solidified by heating and cooling so that any scrap generated in processing can be theoretically reused. No chemical change generally takes place during forming. Usually, thermoplastic polymers are supplied in the form of pellets, which often contain additives to enhance processing or to provide necessary characteristics in the finished product (e.g., color, conductivity, etc.). The temperature service range of thermoplastics is limited by their loss of physical strength and eventual melting at elevated temperatures.

Main Thermoplastic resin used are:

Polypropylene (PP)
It is similar to polyethylene, but each unit of the chain has a methyl group attached. It is translucent, autocavable, and has no known solvent at room temperature. It is slightly more susceptible to strong oxidizing agents than conventional polyethylene because of its many branches (methyl groups, in this case). Polypropylene is noted for its excellent chemical resistance in corrosive environments. This polymer is easily welded and machined.

TYPICAL PROPERTIES OF PP ARE:

• Clean/High Purity
• Good Dimensional Stability
• Good Organoleptic Properties
• High Clarity
• High Flow
• High Stiffness
• Homopolymer
• Low Warpage
• Narrow Molecular Weight Distribution
• Nucleated

Polyethylene (PE) Plastic
Huge family of resins obtained by polymerizing ethylene gas, and it is available in a range of flexibilities. Polyethylene can be formed by a wide variety of thermoplastic processing methods and is particularly useful where moisture resistance is required. Low-density polyethylene (LDPE) has more extensive branching, resulting in a less compact molecular structure. High-density polyethylene (HDPE) has minimal branching, which makes it more rigid and less permeable than LDPE. Linear low-density polyethylene (LLDPE) combines the toughness of low-density polyethylene with the rigidity of high-density polyethylene.

TYPICAL PROPERTIES OF PE ARE:

• Good Processability
• Food Contact Acceptable
• Antioxidant
• High ESCR (Stress Crack Resist.)
• Low Density
• High Impact Resistance

Acrylic-based polymer
Acrylic polymer developed especially for use in the Medical Device Industry. The material is transparent and tough offer gamma and ETO sterilization resistance, and they are easy to process and weld easily to PVC. Typical applications include disposable medical diagnostic devices such as cassettes and cuvettes.

TYPICAL PROPERTIES OF acrylic-based polymer compounds are:

• Excellent chemical resistance to fats and oils
• Excellent bonding and welding capabilities
• Excellent bonding to PVC tubing
• Good impact strength
• Good light transmission
• Good resistance to EtO, gamma and E-beam sterilization
• Superior resistance to lipids and alcohol
• Excellent ductility

Nylon (PA6)
This is a group of linear polymers with repeated amide linkages along the backbone. These are produced by an amidation of diamines with dibasic acids, or polymerisation of amino acids. Nylon is strong and tough. It resists abrasion, fatigue and impact. Nylon offers excellent chemical resistance with negligible permeation rates when used with organic solvents. However, it has poor resistance to strong mineral acids, oxidizing agents and certain salts.

TYPICAL PROPERTIES OF PA 6 ARE:

• Good Chemical Resistance
• Good Colorability
• Good Corrosion Resistance
• Good Processability
• Good Toughness
• Good Wear Resistance
• High Rigidity
• High Strength
• Low Friction

Healthcare Air Filtration Guide

Air filtration products to prevent small particulate matter or micro-organisms from entering the body demands a comprehensive understanding of the dynamics of motion from which ideas on how to inhibit that motion may be developed. GVS manufacturers both electrostatic and mechanically pleated filters.

GVS electrostatic filters utilise a unique patented ‘triboelectrical charge exchange’ between a specially developed blend of polymers to induce a highly stable electrical charge on every individual fibre in the media to more easily trap small particles. The advantages of this type of filter are: efficiencies up to 99.9999%, low manufacturing costs and ease of construction.

Fig 1: Electrostatic Filter – 50% of fibres + charged: 50% of fibres – charged.

GVS mechanical pleated filters carry hydrophobic properties which provide a complete barrier to viral pathogens under normal clinical conditions. Efficiencies up to 99.99999% are available among GVS range of mechanical pleated filters. The advantage of an ability to cope with all particle sizes, high efficiency over long periods, increased efficiency over time, and the highest possible performance (99.99999% on 24 Hour Test) need to be balanced against the higher cost of production.

Fig 2: Direct Interception: This occurs when a particle passes within half of its diameter of a fibre’s surface and is most effective for particles in the 0.3 – 1 micron range. The smaller the pore size, the greater the efficiency in interception. Fig 3: Inertial Impaction: This results from a directional change from the gas flow. Particles of one micron and greater remain on their original course and impact on the surface of the media as a result of the large mass and inertia. Fig 4: Diffusion: Particles of less than 0.3 microns are captured as a result of undergoing considerable Brownian movement.

There are certain characteristics that a filter should have in order to assure that it is going to be safe and secure in use within a patients breathing system. Its primary function is as an effective barrier to prevent any cross contamination in the clinical environment. It needs to be effective against Bacteria, Virus and any fluids that may be present in the patient’s airway. Medical filters performance can be validated in two ways.

Bacterial and viral testing
This is normally performed at an independent test facility which develops specific protocols to simulate the types of challenges that a filter may see in the clinical setting. A challenge particle is chosen to simulate the size of the commonly occurring bacteria and viruses. Generally these tests are not conducted using a “live” virus due to the cost and safety issues. GVS has appointed Nelson Laboratories, Utah, USA as independent test facility. Their bacterial test protocol uses Staphylococcus Aureus as a challenge organism which has an approximate size 0.6 mm and the viral test uses an X174 Bacteriophage which has a size of 0.027 mm. It is worth noting that the HIV virus is 0.08 mm and Hepatitis C is 0.02 mm so the test protocol does offer a clinically relevant reflection of their performance.

Penetration test
A standard BS EN 13328 -1 2002 (Breathing System Filters for Anesthetic and Respiratory use. Part 1 Salt Test method to assess filtration performance) has been developed as a method of benchmarking the performance of one filter against another. The test requires the filter to be challenged by a 0.3 mm Sodium Chloride particle at a flow rate of 30 Liters per minute. The level of penetration is measured and the resulting efficiency reported as a percentage. i.e.if a filter has penetration rate of 0.5% the filters performance will be recorded as 99.5% efficient. This test allows a direct comparison of how individual filters perform. Under this system a filter must be more than 99.97% efficient to classified as a HEPA filter. All of the Air Safety pleated filters are individually tested during manufacture to confirm that they are all HEPA performance.

The quality of connections of the filter housing is vital to ensure a safe secure fitting within the patients breathing system during clinical use. All of the 15mm & 22mm tapered connections are tested and comply with ISO 5356 for maximum patient safety. It is now common clinical practice to continually measure the gas that the patient is breathing in and expiring during the any procedure. The Air Safety filters have been designed to comply with ISO standards to ensure a safe secure fit to monitoring devices. In addition the “Cap & Strap” is an integral part of the molding minimizing the possibility of it becoming detached and inadvertently occluding the airway, improving patient safety. The products are all designed to meet the clinical requirements from the smallest baby to the largest adult, with a focus upon minimal resistance, minimum weight and product dead space, combined with the maximum possible product efficiency.

Clinicians may choose a combined product which offers both filtration and humidification (HMEF) to the respiratory gases. This helps alleviate any symptoms associated with breathing cold dry medical gases for a prolonged period of time. The performance of all HME products is verified by independent testing of the product against ISO 9360.

Tidal Volume: (VT) The volume of gas inhaled and exhaled by the patient during one respiratory cycle. The average for a 70 Kg adult is 500 ml.

Minute Volume: (MV) The quantity of gas exhaled from the lungs per minute; i.e. the tidal volume multiplied by respiratory rate. An average 70Kg Adult with a respiratory rate of 12 breaths per minute (500ml x 12) would have a minute volume of 6 litres.

Dead Space: There are two types.

• 1) Anatomical Dead Space is the volume of the patient airways of the nose, mouth, and trachea down to the level of the alveoli, representing the portion of inspired gas unavailable for exchange of gases with pulmonary capillary blood. The average anatomical dead space of a 70 Kg adult is 150ml.
• 2) Breathing System Dead Space is the volume of any breathing system components which is adding to the portion of the inspired gas that is unavailable for exchange of gases with pulmonary capillary blood.

Resistance: This is an expression of the amount of effort that is required to make an inspiratory or an expiratory breath.

Efficiency: This will be the level of filtration protection or function that the device can deliver. The efficiency of the filter is normally expressed as a reflection as the number of micro organisms that pass through the filter media when it is challenged. This filter is then described as being X% efficient. The X% is an expression of the number of organisms penetrating the filter when challenged by an aerosol containing 1,000,000 micro organisms. The table below explains the relevance of the X% on performance and level of protection in the clinical environment.

Significance of % removal of bacteria/viruses

Number of Organisms Challenging the Filter	Number of Organisms Passing through the Filter	% Efficiency
1,000,000	100,000	90
	10,000	99
	1000	99,9
	100	99,99
	30	99,997
	10	99,999
	1	99,9999

A 99.99999% filter is 10 times more efficient than 99.9999%,100 times more efficient than 99.999 %, and 1000 times more efficient than a filter rated at 99.99%.

HME: Heat Moisture Exchanger. These devices allow heat and moisture to be captured from expired gases and then returned to the patient in the inspired gases. This is established by testing against ISO 9360 -1 &2 2000 “Anesthetic Respiratory Equipment, HME’s for humidifying respired gases in humans”.

Capnography: This is the measurement and graphic display of CO2 levels in the airways, which can be performed by infrared spectroscopy. A small sample of inspired and expired gases is taken via the gas sampling port on the filter. Capnography assists in the management of the patient by providing continuous and non invasive monitoring of ventilation in critically ill and anaesthetized patients. It allows early detection of clinically significant changes in respiratory status by displaying changes in the amount of CO2 and abnormal CO2 waveforms. ISO: International Standards Organization is a group which has developed test and performance standards to introduce normalized standards of global practice and help improve patient safety.

Laboratory Application and Selection Guide

GVS Laboratory is a fully integrated producer and supplier of membrane-based solutions for the life sciences, environmental monitoring and process filtration markets. Our membranes are used for laboratory research, food and beverage production, medical diagnostics, pharmaceutical research and bio-processing.
All of our membranes are manufactured at our facilities in North America, allowing for easy and cost-effective customization. Because we manufacture more types of membranes than any other company, we are able to partner with you for all of your OEM Membrane needs.

  

 

 

Performance - GVS Life Sciences membranes have a long history of use in many applications. From development through continuous improvement and investment, we strive to offer membranes that exceed performance specifications.

Consistency - The GVS Life Sciences Quality Management System ensures adherence to ISO guidelines, providing a quality product with every run, every time. Documentation and support are there to ensure you meet your regulatory and customer requirements. Our commitment to quality and consistency is evidenced by repeat business from many major life science customers.

Support - A membrane research team of five Ph.D.s and nine engineers provides the expert technical assistance you need to choose the membrane type and dimension to suit your specific applications.

Product Range - Our seven casting lines combined with the depth of our knowledge make us uniquely qualified in the field of membrane-based life science solutions.

Flexibility/customization - Our in-house casting capabilities combined with our conversion facilities allow us to customize almost any offering.

Efficiency - GVS Life Sciences is a nimble and efficient company with low overhead and administrative burdens.
Our size and structure help us to control costs and provide you direct access to the decision-makers
and technical experts.

Chemical Compatibility

 

Mobility Filtration Guide 

Woven fabric Filtration media  

Precision and maximum performance screens for excellent filter solutions  

Filtration through a wire and synthetic meshes is mechanical filtration. Mesh is specified by its mesh size, which is just one of the several key characteristics.  

The monofilament precision woven fabric used by GVS for automotive filters is manufactured with uniform weave and accurate open-mesh structure, which guarantees to achieve any contamination reduction needs through a wide range of opening sizes, a precise pore size and square shape geometry, high throughput and flow rates.  

Types of Weave  

Plain weave
This wire is produced by the constantly alternating over and under threading of the warp and weft wires. This mesh has square openings and where wire sizes that are the same in warp and weft. It is the simplest, the best known and the most commonly used type of weave, producing particularly accurate mesh sizes.  

Twill weave
Special Mesh where weft wire passes alternatively over and under two warp wires, and has been cre- ated to compensate for the diagonal distortion of twill weaves. This weave is suitable if relatively small mesh sizes are required with relatively heavy-gauge wires.  

Plain Dutch weave
Similar to a plain weave, but the warp wires have greater diameter than the weft wires. The proximity of the weft wires to each other results in a so-called ‘closed mesh’. Its particular advantages lie in its efficient through-flow capacity and uniform apertures.  

Twill Dutch weave
This weave shows a combination of twill and dutch weave. One heavier warp wire is woven over multiple lighter weft wires, that are the double the weft wires by comparison with a plain braid. The advantages lie in its smooth surface and ultra-fine filtration. 

 

 

 

Mesh characteristics 

Raw materials
GVS open mesh fabrics offer you the greatest design flexibility. Raw materials used for the monofilament are polyamide (PA6.6), polyester (PET) and polypropylene (PP) in particular, but other materials for high- performance filter materials (PEEK) and fluorinated polymers (ETFE) or metals (Al, Cu, Ag, Au, Cu-Al, Ti and Ni) are also available upon request.  

Mesh opening
This is the size (micron) of any window or opening. The openings are tested by electronic analysis image systems during production.  

Open area
This is a percentage (%) of the total mesh area which is “open” to let the flow go through. It’s important to have high open area percentage to reduce flow restriction. This is also tested by electronic analysis image systems during production.  

Mesh count
This is the quantity of threads per cm (n/cm) or per inch (n/in).  

Thread diameter
This is the diameter (micron) of the filament. It is also tested by electronic analysis image systems during production.  

Weight of the mesh
It is important to qualify the quality of the mesh, (g/m2) or (oz/yd2) . 

Thickness of the mesh
Thickness is expressed in microns (µm) and its stability is very important to achieve the proper handling of the mesh during production.  

Effective Filtration Area (EFA)
This is the actual filtration area in a device that is subject to filtration. For instance, in a tubular filter, the frame (socket, two ribs and top cover) made by plastics should be eliminated from the calculations of the device EFA. In mesh filters you should only eliminate the seal area.  

Micron Retention
The diameter of the largest round particles which can pass through a filter. Since absolute Micron Retention can change during filtration, aperture size can be determined by Bubble Point and Glass Bead Tests methods.  

Bubble Point Test
The pressure required to force air bubbles through a wetted mesh. These tests are typically performed with water; however, test can be conducted on mesh using test liquids other than water. The BP is an indication of the pore size. The average size can then be calculated by taking into account surface tension, liquid density, temperature and immersion depth.  

Glass Bead Test
A mixture containing glass beads is passed through the mesh, the diameter of the largest bead passing through is considered as the absolute micron retention.  

Filter Efficiency (FE)
This is the quantity of particulate retained compared to the total quantity of particulate to which the filter is challenged. It is expressed in % and refers to a specific size of particles.
The filter efficiency is determined by a pass test which allows the measurement of the percentage of particles which are removed by the filter. It is expressed by a beta rating representing the effectiveness of the filter that can be calculated as follows: 

 

 

Nonwoven fabric Filtration media  

Excellent barrier properties to protect your parts from liquids and dust  

Nonwovens are typically manufactured by putting fibers together in the form of a sheet or web, and then binding them either mechanically, with an adhesive or thermally.  

They have a porous structure throughout the cross-section and are able to remove particulate from liquid or gaseous streams.  

Typically, nonwoven filtration media are characterized by pores in the range from 1 to 500 micron, by high dirt holding capacity, high flow rates, and low pressure drop. Nonwoven fabrics are manufactured from many grades of cellulose and most natural and synthetic fibers such as polyester, polypropylene, acrylics, fluoropolymers, polyamide and glass.  

In the 1 to 20 micron mean flow pore range, the cost of nonwovens are much less than membranes and the dirt holding capacity is generally far superior.  

Several automotive parts are actually made with today’s engineered nonwoven fabrics. Typical GVS applications include fuel, oil, and air filtration. Special fabric post-treatments, such as idrorepellent and oleorepellent treatments can yield treated nonwoven gradient media having characteristics which improve filtration efficiencies and/or flow rates.  

Advantages of nonwoven fabrics include their versatility, diverse functionality, and low price-performance ratio.  

Many filtration and separation applications require stiffness, minimal flex, and rigidity or even low stretch. Therefore, it is evident that filter design engineers make their media selections based on performance trade-offs. This is routinely studied at GVS. 

 

Typical nonwovens  

Wet-laid, Spunbond and Meltblown nonwovens  

Nonwoven fabrics are prepared by a polymer melt process, where fibers are created in a spinning operation and immediately cast on a moving belt forming a continuous web. Fiber diameters are controllable and measured in microns. Recently nanotechnology permits the preparation of sub-micron diameter polymeric fibers. Glass fibers have been available for many years below 1 micron in diameter and are commonly utilized in HEPA (High Efficiency Particulate Air) and ULPA (Ultra Low Penetration Air) gas filtration. 

Wet-laid filtration media are very regular and are characterized by narrow pore size distribution.  

Spunbond fabrics serve in applications needing a nominal pore size above 5 micron. They are not as regular as wet laid materials.  

Meltblown nonwovens have extremely fine fiber diameters, but are not strong fabrics. These materials are often used as filter media being able to capture very fine particles and having excellent dirt holding capacity. They are formed by fibers in the 1-10 micron diameter size range and are character- ized by lower pore size (even 1-3 micron). 

 

 

Test methods evaluation for nonwoven media  

Standard Test Dust
Natural Arizona ground mineral test dusts are available in the following grades: A.C. Fine (ISO 12103 Pt1 A2 FINE) and A.C. Coarse (ISO 12103 Pt1 A4 COARSE). 

Beta Ratio
Ratio of particles present upstream to particles present downstream the filter.  

Dead end filtration
The stream to be filtered flows perpendicularly through the filtration media.  

Depth Filtration
The filter captures contaminants on the surface and into the cross-section (the porous part) of the filter media.  

Filter Efficiency
Is the percentage of particles of a specific size retained by a filter. It is calculated by [1-(particles in filtrate)/(particles in feed)]  

Filter Capacity
It is indicative of the filter’s life. It is expressed as the amount of standard test dust required to increase the pressure drop of the filter to a predetermined level, at least 3 times of its initial pressure drop. It is typically expressed in g/cm².  

Flow Rate
The quantity of liquid or gas which flows through the filter at a given temperature and pressure. It is expressed in l/min.  

Flux
The quantity of liquid or gas which flows through the unit area of a filter at a given temperature and pressure. It is expressed in l/min m².  

Frazier Permeability
It is the air flow in CFM which passes through one square foot of filtration medium at 0.5 inch differential water pressure.  

Gurley Permeability
It is the time required for a fixed volume of air to pass though a filter medium placed within a specific apparatus  

HEPA
An air filter or filtration medium which can reject 99.97% of particles when challenged with DOP 0.3 micron particles under specific conditions   

Multi-pass system
Standard test dust is prepared in slurry form, mixed with the testing fluid in the system main tank and circulated through the test filter. The dust not retained by the filter is recycled to the main tank.  

Pressure Drop (∆P)
Difference in pressure between upstream and downstream of the filtration medium.  

Single-pass system
Standard test dust is prepared in slurry form, mixed with the testing fluid in the system main tank and circulated through the test filter. The dust not retained by the filter is not recycled to the main tank.  

SULPA (Super ULPA)
An air filter or filtration medium which can reject 99.9999% of particles when challenged with DOP 0.3 micron particles under specific  conditions.  

Tangential (Crossflow) Filtration
The stream to be filtered flows tangentially to the filtration media, part is filtrated and part is recycled. (crossflow)  

ULPA
An air filter or filtration medium which can reject 99.999% of particles when challenged with DOP 0.3 micron particles under specific conditions. 

 

Polymeric membrane filtration  

Filtration through a membrane allows for continuous exchange of gases and vapors, providing pressure equalization within the auto parts enclosures that are often exposed to rapid temperature fluctuations, caus- ing extreme changes in internal pressure and creating a vacuum that puts stress on the seals. 

 

Hydrophobic & Oleophobic membranes  

Microporous hydrophobic & oleophobic membranes allow air to pass freely through the filter media, equalizing the pressure differential between the enclosure and the ambient temperature. Small pore size reduces liquid penetration speed through the filter due to slow airflow, while larger pore size lets liquids pass through faster and easily reduces retention performance. Oleophobic membranes are post-treated to repel low surface tension fluids such as oils and alcohols.
Key properties and pore size (ranging from 0.02 to 10 µm), particular environmental conditions and specific surface tension of a fluid should be considered before choosing the proper filter media for a given application.

 

Membrane Specifications  

Pore size
Pore size is determined by the size of the particle that is expected to be retained with a defined degree of efficiency. Pore size is typically stated in micrometers or microns (µm), and should clearly be des- ignated as either nominal or absolute.  

Nominal pore size is the ability to retain a majority (60% - 98%) of particles having a specific dimension. 

Absolute pore size is the ability to retain the 99,999% of particles of a specific dimension under defined test conditions (particle size, challenge pressure, concentration, detection method).  

Retention capacity
Retention efficiency is also dependant on such process conditions as concentration, operating pressure etc. Rating parameters can vary among manufacturers. When the pore size, or retention, is “nominal”, it should be stated as a particle size and a percent, i.e., 99.97% retention of 0.3 µm particles.  

Chemical compatibility
This is the ability of the membrane to resist to chemicals without mechanical or chemical damage from chemical exposure. Information about the liquid used with a specific filter material should be outlined before application to determine compatibility, GVS can assist customers in choosing the proper filter (and housing) materials.  

Extractables
Extractables are contaminants (typically chemicals) that elute from the filter which might affect qual- ity of the effluent. Wetting agents (surfactants), and manufacturing residuals are the main causes of undesired   extractables.  

Binding
This is the property of substances to be filtered having affinity with membranes. This could be a positive effect in some circumstances, but most of the time it can create adverse effects. Particularly it could lead to loss of active components of the liquid to be filtered reducing its beneficial effect. 

 

Water Breakthrough (WBT)
The pressure at which aqueous solutions will pass through a hydrophobic membrane is called the water breakthrough (WBT) or water intrusion pressure (WIP).  

Air Flow (AF)
It is the amount of air that passes through a fixed surface of membrane with a specific applied pressure.  

Filter Efficiency (FE)
Quantity of particulate retained compared to the total quantity of particulate to which the filter is chal- lenged. It is expressed in % and referred to a specific size of particles.  

Effective Filtration Area (EFA)
This is the actual filtration area in a device that is subject to filtration. For instance, whereas a 25 mm device may start out with a disc of filter media that is cut to 25 mm, the sealing surfaces should be eliminated from the calculations of the device EFA.  

Contact Angle Measurement
The measure of the angle between a drop of liquid and a surface of a solid is used to determine the surface hydrophobicities or oleophobicities of membranes and to assess their separation potential.  

 

Polymers for injection  

The automotive industry is the largest consumer of plastic materials since their properties meet require- ments for a large variety of automotive applications. They are widely used in original equipment and after-market sectors.
Usually, thermoplastic polymers are supplied in the form of pellets, which often contain additives to enhance processing or to provide necessary characteristics in the finished product (e.g., color, conductivity, etc.). The temperature service range of thermoplastics is limited by their loss of physical strength and eventual melting at elevated temperatures.  

Main Thermoplastic resin used in Automotive Applications  

Nylon (Polyamide) - comprises the largest family of engineering plastics with a very wide range of applications. Typically Nylon - especially if glass fiber reinforced - can replace metal in many applica- tions due to its good resistance to wear and abrasion, good mechanical properties even at elevated temperatures, low permeability to gases and good chemical resistance. GVS typically uses PA for powertrain applications such as fuel injector, fuel pumps filters and filters in transmission applications.  

Nylon Generics	Typical  Nylon  Automotive Applications
Nylon 66 - Housings Nylon 6 - Connectors PPA - Gears Nylon 12  Nylon 66/6 Nylon 612	Automotive Under the Hood

 

Advantages of Nylon	Disadvantages of Nylon
Heat Stabilized Lubricated- Chemical Resistance Good Dimensional Stability Flame Retardant  Impact Modified Good Toughness Heat Resistance	High moisture pick-up with related dimensional instability Requires UV stabilization High shrinkage in molded sections High moisture absorptivity degrades electrical and mechanical properties

Acetal (POM) - A thermoplastic produced by the addition of polymerization of an aldehyde through the carbonyl function, yielding unbranched polyoxymethylene chains of great length. The Acetal resins are among the strongest and stiffest of all thermoplastics, and are characterized by good fatigue life, low moisture sensitivity, high resistance to solvents and chemicals, and good electrical properties. Because of these properties, acetals often compete with nylons for many of the same applications. GVS typically uses POM in fuel in tank filters for its good static dissipation properties, fuel resistance and design flexibility. 

Acetal Generics	Typical Acetal Automotive Applications
Acetal (POM) Copoly Acetal (POM) Homopoly Acetal (POM) Copoly Alloy	fuel system filters  Gears  Actuators

 

Advantages of Acetal	Disadvantages of Acetal
Chemical Resistance  Creep Resistance  Dimensional Stability  Fatigue Resistant Lubricated Wear Resistance	Low Poor resistance to acids UV sensitive Flammable

Thermoplastic Elastomers (TPE) - TPEs are a family of polymers that can be repeatedly stretched without permanently deforming the shape of the part. Unlike rubber-like elastomers, they do not require curing or vulcanization, as they are true thermoplastics. There are six main thermoplastic elastomer groups found commercially; styrenic block copolymers, polyolefin blends (TPOs), elastomeric alloys, thermoplastic polyurethanes (TPUs), thermoplastic copolyesters and thermoplastic polyamides. GVS uses TPEs especially for automotive vent applications. 

TPE Generics	Typical  TPE Applications
TPE TPO (POE) SEBS TPV SBS EPDM TPEE PEBA	Seals Vents Gaskets

 

Advantages of TPE	Disadvantages of TPE
TPE TPO (POE) SEBS TPV SBS EPDM TPEE PEBA	Degraded by UV Flammable, but retarded grades available Attacked by chlorinated solvents and aromatics Difficult to bond Several metals accelerate oxidative degrading Low temperature impact strength is poor

 

 

 

Polyphenylene Sulfide (PPS) - Engineering thermoplastic resins having a symmetrical, rigid backbone chain consisting of recurring p-substituted benzene rings and sulfur atoms, Polyphenylene Sulfide exhibits excellent heat resistance, thermal and dimensionally stability, as well as outstanding chemical resistance, high stiffness and good retention of mechanical properties at elevated temperatures. The major use for Polyphenylene sulfide is in automotive parts and electrical/ electronic parts. GVS typically uses PPS for motor air management applications such as plastic valves and insert molded shafts. 

 

PPS Generics	Typical  PPS Applications
PPS  PPS+PPE  PPS Alloy  PPS+Nylon	Automotive Applications  Electrical/Electronic Applications Pump Parts  Compounding Metal Replacement Coating Applications General Purpose Housings Industrial Applications

 

Advantages of PPS	Disadvantages of PPS
Lubrificated   Good Chemical Resistance  Flame Retardant  Electrically Conductive  High Heat Resistance Linear Polymer Structure Good Thermal Stability High Strength Good Flow	Difficult to process (high melt temperature) Comparatively high cost Fillers required to get good impact strength Subject to warpage and brittleness

Polybutylene Terephthalate (PBT) - It is a semi-crystalline polymer combining excellent mechanical and electrical properties with robust chemical resistance. The PBT - based resins deliver high flow and rapid crystallization. This makes them fast-cycling. The PBT product range includes a wide variety of reinforced, filled, impact-modified and flame-retardant grades which are great for injection moulding. The combination of high mechanical and electrical properties, good thermal stability and superior chemical resistance creates many automotive application opportunities and GVS typical example include fuel pressure regulator devices.  

 

Advantages of PBT	Disadvantages of PBT
High strength Excellent stiffness-to-weight ratio Good toughness Low moisture absorption Very high electrical insulation properties Low dielectric loss Broad chemical resistance High temperature capability Good overall environmental resistance Flame retardancy Good mouldability with fast cycles	Automotive Applications: Windshield wiper covers mirror housings cowl vents handles fans  fuel system components connectors sensor housings fuse boxes actuator cases power relays switches motor components ignition system components

 

Metals for automotive applications 

Copper (Cu)  

Copper and its alloys are essential components of many of the latest parts in the modern automotive industry. It is malleable and ductile and it can be hammered and molded into several shapes, or drawn into wire. New technological advances in copper are proven to produce more durable and higher quality parts in automotive applications for the future. It’s density of 8.96 _g·cm-3 (Kilogram per cubic metre) is slightly superior to steel and its melting point is 1084.62°C (1984.32°F).  

Copper Advantages  

• Superior thermal and electrical conductivity
• High resistance to corrosion
• Easy to work in manufacturing and refining 

Many copper alloys exist, representing the third most used metal worldwide after stainless steel and
alluminium. There are close to 400 different Copper and Copper-alloy compositions, grouped into different categories. UNS Classification identifies two kinds of copper: wrought alloys and cast alloys. 

 

Brass   

Widely used in the automotive industry, Brass is an alloy formed of copper and zinc. Proportions can vary to create alloys with different proprieties. Thanks to Zinc that can vary from 5% (C210) to 40% (C280), brass is more malleable and ductile than Copper and presents a lower melting point (from 900 to 940°C depending on composition).
To preserve a good mechanical conservation, an alloy must have a thin granular material. Alpha brasses (less than 35% zinc) are malleable and can be worked cold, while Alpha-beta brasses with 35-45 % zinc and Beta brasses with 45-50 % zinc content are harder and stronger and they are
suited only for hot working.
In addition to the traditional binary brass, with a lower percentage of zinc (20-30%), there are also ternary brass, formed by copper, lead and zinc (C3) or by copper, zinc and tin (C4). Leaded brasses (C3) present an excellent machinability. With a lead percentage varying from 0,3 to 3,5%, they are manly used for making screws, bolts and other worked tools. In Tined brasses (C4) like Admiralty brass and Naval brass, tin inhibits their dezincification. To improve corrosion resistance, they’re mainly used for naval applications. 

 

Heat treatments and recrystallization methods allow you to control not only the desired hardness but also the desired strength, ductility and toughness of brass and brass alloys, influencing the evolution of the material microstructure and its mechanical properties. Heat treatments serve several purposes such as annealing, stress relieving, homogenizing and precipitation hardening.

Annealing - By heating cold metal to a high temperature until recrystallization occurs, it is possible to softening or annealing it. If maximum softening is desired, by heating well above the recrystallization temperature to cause grain growth. Light annealing is performed at a temperature slightly above the recrystallization temperature, while soft annealing is performed several hundred degrees higher.

Stress Relieving - Stress relieving is aimed to reduce or eliminate residual stress, thereby reducing the likelihood that the part will fail by cracking or corrosion fatigue in service. Parts are stress-relieved at temperatures below the normal annealing range that do not cause recrystallization and consequently soften the metal.

Homogenizing - Homogenizing is applied to dissolve and absorb segregation and coring found in some cast and hot worked materials, chiefly those containing tin and nickel. Diffusion and homogenization are slower and more difficult in tin bronzes, silicon bronzes and copper nickels than in most other copper alloys.

Precipitation Hardening - High strength in most copper alloys is achieved by cold working. Solution treating and precipitation hardening is applied to strengthen special types of copper alloys.

 

Aluminum  

It is one of most versatile engineering and construction material and it is the second most used material in new Automotive applications. Aluminum is a soft, very light weight metal. It is malleable, ductile and can be easily molded since its mass is roughly one-third of iron and copper. It is found primarily in bauxite ore and it is extracted by electrolysis. It has high structural and excellent corrosion resistance and durability and it is a good thermal and electrical conductor (third best after silver and copper). However aluminum alloys have a high coefficient of thermal expansion which makes them unsuitable for high temperature applications.
Aluminum products include rolled, extruded, cast and forged forms, offering the possibility to cover a wide range of automotive applications requirements such as Brake Calipers, Bumpers, Chassis, Cradles, Closure Panels, Control Arms, Engine parts and Suspension parts.  

Heat treatments
The four digit designation of aluminum alloys is usually accompanied by any of the following four letters:
F for fabricated (forgings and castings prior to heat treatment), O for annealed, W for solution heat treated, and T for heat treated to stabilize temper conditions other than O or F. The following temper designations are commonly used:
T3 - solution heat treated,cold worked and naturally aged.
T4 - solution heat treated and naturally aged.
T6 - solution heat treated and artificially aged.
T7 - solution heat treated and overaged.
T8 - solution heat treated, cold worked and artificially aged.
In addition to these heat treatments, a heat treat condition number can have additional numerical information like T7xx, where the xx describes either a stress relieving treatment done to the alloy or the extent of aging.

Aluminum alloys usually have a 4-digit designation. The first digit designates purity or alloy type. The second digit indicates modifications of the alloy. Only in 1xxx series the third and fourth digits indicate the purity. In the other series, the third and fourth digits identify different alloys.
1xxx - Aluminum (at least 99.0% pure) - Very high corrosion resistance, high electrical and thermal conductivity, good formability, low strength and not heat treatable.
2xxx - Aluminum-Copper alloy - High strength-to-weight ratio, low corrosion resistance and heat treatable.
3xxx - Aluminum-Manganese alloy - Good formability, moderate strength and not heat treatable.
4xxx - Aluminum-Silicon alloy - Lower melting point than normal and not heat treatable.
5xxx - Aluminum-Magnesium alloy - Good corrosion resistance, easy to weld, moderate to high strength and not heat treatable.
6xxx - Aluminum-Magnesium-Silicon alloy - Medium strength, good formability, machinability and weldability, corrosion resistant, heat treatable.
7xxx - Aluminum-Zinc alloy - Moderate to very high strength, heat treatable and prone to fatigue.
Aluminum-Lithium alloy (no numerical designation) - 10% lighter and 10% stiffer than other alumnium alloys and superior fatigue performance.
Aluminum-Iron-Molybdenum-Zirconium alloy (no numerical designation) - High temperature tolerance, of 600°F.

 

Stainless Steel  

Stainless steel is the term used for a large number of steels showing an excellent corrosion-resistance in a large number of conditions, due to their 10.5% mass minimum percentage of chromium and a 1.2% maximum of carbon content. It is protected by a very thin chromium-rich oxide film, which prevents further direct contact between the metal and its environment.
Stainless steel’s different mechanical and physical properties are mainly determined by solution characteristics and combination with chromium since nickel, molybdenum, titanium, niobium and other elements may also be present. There are several types of stainless steel: Ferritic, Martensitic, Austenitic and Duplex. 

Ferritic steels are magnetic, have a low carbon content and contain chromium as the main alloying element, typically at the 11-17% levels.
Martensitic steels are the most used group of stainless steels by GVS. They are magnetic and they typically contain 12-18% chromium and a moderate carbon content (0,10%). They have high strength and rather low ductility (or formability)
The Austenitic steels are non-magnetic and can be easily welded, containing 7-20% nickel, which increases their corrosion resistance, in addition to the 17-25% level of chromium. Austenitic steels have lower strength and high ductility. 
Duplex steels are used where combinations of higher strength and corrosion resistance are needed.
Super austenitic grades and precipitation hardened grades of steel are also available. Duplex and ferritic steels occupy an intermediate yield strength and ductility position.

Martensitic steels provide the highest strengths, since mainly carbon, but also manganese, silicon, chromium, molybdenum, boron, vanadium, and nickel are used in various combinations to increase hardenability. High levels of strength can be reached by cold working stainless steels. Cold worked austenitic and duplex stainless steels generally offer an interesting combination of strength and formability, in terms of weight-saving potential.
Sheet or tube formed steels can be used in the automotive sector for auto body, closure, suspensions, wheels, bumpers, fuel tanks, bars and rods. Alloy steels are usually designated by distinct AISI (American Iron and Steel Institute) mainly four-digit numbers. The first two digits indicate the leading alloying elements, while the last two digits give the nominal carbon content of the alloy in hundredths of a percent. Occasionally it is possible to find five-digit designations where the last three digits tell that the carbon is actually over 1%.

Personal Safety Filtration Guide - Europe and Other Regions 

Indications for the choice of respiratory protection devices are based on current knowledge. Before each use of the ELIPSE respirator devices, the buyer and user must ensure that the masks and filters used are those specified for the type of pollutant and its concentrations. The ultimate responsibility concerning selection and use of products lies solely with the buyer and user.  

TYPES OF FILTERS 

Dust filters are able to retain airborne particulates and are offered in various constructions, which enhance the filters characteristics with use of various types of filter material with different thickness, porosity and surfaces, to protect against particulates, gases and nuisance odours. Activated carbon cartridge filters contain specific activated carbon, which retain certain gases and vapors by adsorption, while combined filters can remove both gases, vapors and particulates.  

TECHNICAL CHARACTERISTICS OF FILTERS 

There are various types of particulate dust filters which have different filtration efficiency. Depending on which you choose, you can have the most suitable means of protection against environmental pollution conditions. The airborne particles are retained by the filter by means of mechanical and/or electrostatic action.  

In the case of gas filters, substances are retained by the chemical-physical action of activated carbons in the filter, able to adsorb and neutralise contaminants.
It is assumed that the efficiency of gas and vapor interception on adsorbent material is 100%, at least until the completion of the capacity of the filter material. For gas filters, we refer to; time to completion or, rather, the period beyond which the filter is saturated and the pollutant begins to pass through the filter. This 'breakthrough' time depends on the quantity of adsorbent material used, on its filtration capacity against the pollutant and on environmental concentrations.  

Protection against particulates (dust, mists and toxic fumes)  

	Dust: dust forms when a solid material is broken down into tiny fragments. The finer the dust, the higher the risk.
	Mists: mists are tiny droplets that are formed from liquid materials by atomisation and condensation processes, such as spray painting.
	Fumes: fumes are formed when a solid material is vaporised by the high heat. The vapor cools quickly and condenses into very fine particles.

Respiratory filters have 3 classes of protection with increasing efficiency, normally expressed with a Nominal
Protection Factor (NPF) which is the ratio between concentration of the contaminant in the environment and
inside the mask. The resulting factor indicates how many times the device can reduce the external concentration.

Classes of efficiency of dust respirators
P1 (Facial Anti-Dust Filter class 1) 80% filtration : 4 (NPF)
P2 (Facial Anti-Dust Filter class 2) 95% filtration : 10 (NPF)
P3 (Facial Anti-Dust Filter class 3) 99,95% filtration : 40 (NPF)
Anti-dust filters are distinguished by the colour WHITE  

Protection against gases and vapours Gases and vapours: gases and vapours are molecules, so small that they penetrate particulate filters. You need to use a chemical filter against these. Anti-gas respirators have activated carbon filters which, for physical or chemical adsorption, withhold the harmful substances that are distinguished by identifying letters and colours:

 

Type Protection Class  

	A organic gases and vapours with a boiling point above 65°C
	B inorganic gases and vapours (excluding carbon monoxide)
	E acids / acid gases
	K ammonia and organic ammonia derivatives
	AX organic gases and vapours - boiling point <65°C

There are three protection classes for each type of anti-gas filter, depending on the amount of contaminants that the filter is able to adsorb. The choice is therefore determined by the predicted concentration of the pollutant: 

Class 1 is low capacity and can be used until 1.000 ppm
Class 2 is medium capacity and can be used until 5.000 ppm
Class 3 is high capacity and can be used until 10.000 ppm

Combined filters (gas and dust), besides the colour of the specific gas/es, include a white band and their marking show all the distinctive letters with their relative efficiency classes. 

Filter Life: 

Filter life depends on a number of variable factors; the wearer’s breathing rate, the characteristics and level of contaminant, length of time a user is exposed to a contaminant, and environmental conditions such as temperature and humidity. Saturated or used filter cartridges will leak trace amounts of contaminant to the wearer, which may be detected via odour, taste, and irritation. If a contaminant is detected filters should be changed immediately. 

Detailed Contaminants Guide (pdf download)

 

 

 

 

 

 

 

 

Personal Safety Filtration Guide - USA and NIOSH 

 

Indications for the choice of respiratory protection devices are based on current knowledge. Before each use of the ELIPSE respirator devices, the buyer and user must ensure that the masks and filters used are those specified for the type of pollutant and its concentrations. The ultimate responsibility concerning selection and use of products lies solely with the buyer and user.

 

 

 

TYPES OF FILTERS 

 

Dust filters are able to retain airborne particulates and are offered in various constructions, which enhance the filters characteristics with use of various types of filter material with different thickness, porosity and surfaces, to protect against particulates, gases and nuisance odours. Activated carbon cartridge filters contain specific activated carbon, which retain certain gases and vapors by adsorption, while combined filters can remove both gases, vapors and particulates.

 

 

 

TECHNICAL CHARACTERISTICS OF FILTERS 

 

There are various types of particulate dust filters which have different filtration efficiency. Depending on which you choose, you can have the most suitable means of protection against environmental pollution conditions. The airborne particles are retained by the filter by means of mechanical and/or electrostatic action.
In the case of gas filters, substances are retained by the chemical-physical action of activated carbons in the filter, able to adsorb and neutralise contaminants.
It is assumed that the efficiency of gas and vapor interception on adsorbent material is 100%, at least until the completion of the capacity of the filter material. For gas filters, we refer to; time to completion or, rather, the period beyond which the filter is saturated and the pollutant begins to pass through the filter. This 'breakthrough' time depends on the quantity of adsorbent material used, on its filtration capacity against the pollutant and on environmental concentrations.

 

 

 

Protection against particulates (dust, mists and toxic fumes) 

 

NIOSH approved respiratory filters have different classes of protection for removal of any particle including oil-based liquid aerosols, with increasing efficiency. Particulate filters are classed as N, R, or P combined with 95, 99, or 100
N - Not resistant to oil mist
R - Resistant to oil mist
P - Protective against all particulates
95, 99, 100 - approximate filter efficiency in % against 0.3 micron particles
P100 particulate Filters capture at least 99.97% of 0.3 micron airborne particles. They are strongly resistant to oil mist.
P100 filters are distinguished by the Magenta colour.

 

 

Protection against gases and vapours 

 

Protection against gases and vapours Gases and vapours: gases and vapours are molecules, so small that they penetrate particulate filters. You need to use a chemical filter against these. Anti-gas respirators have activated carbon filters which, for physical or chemical adsorption, withhold the harmful substances that are distinguished by identifying letters and colours:

 

NIOSH approved Respiratory Gas and vapors filters classification system are distinguished by identifying colors: 

 

	Organic vapors : Black
	Acid gases : White
	Organic vapors and Acid gases : Yellow
	Ammonia and Methylamine : Green
	Any other gas or vapor : Olive

 

Filter Life 

 

Filter life depends on a number of variable factors; the wearer’s breathing rate, the characteristics and level of contaminant, length of time a user is exposed to a contaminant, and environmental conditions such as temperature and humidity. Saturated or used filter cartridges will leak trace amounts of contaminant to the wearer, which may be detected via odour, taste, and irritation. If a contaminant is detected filters should be changed immediately.

 

 

 

Detailed Contaminants Guide (pdf download)

 

 

 

 

 

 

 

 

Bio-Safety Filtration Guide

The United States Centers for Disease Control and Prevention (CDC) categorizes bio hazards at the following levels. Level 1 being minimum risk and Level 4 being extreme risk.  

Biohazard Level 1:
Bacteria and viruses. At this level precautions against the biohazardous materials in question are minimal, most likely involving gloves and some sort of facial protection.

Biohazard Level 2:
Bacteria and viruses that cause only mild disease to humans, or are difficult to contract via aerosol in a lab setting.

Biohazard Level 3:
Bacteria and viruses that can cause severe to fatal disease in humans, but for which vaccines or other treatments exist.

Biohazard Level 4:
Viruses and bacteria that cause severe to fatal disease in humans and for which vaccines or other treatments are not available.

GVS produce a range of Biohazard products including eye protection, body protection and respiratory masks. There are also kits available for specific risk levels. Please see our products pages for more details.

Detailed Contaminants Guide (pdf download)

 

 

Personal Safety Filtration Guide

The GVS Elipse Half-Face Mask represents a major leap in mask design and the development of new technology. The result is a mask that enables the wearer to feel more comfortable and less constricted without compromising the efficiency and effectiveness of the mask. 

For Europe and other regions click here	For USA click here	For Bio Hazard Protection click here

 

Air Safety - Filter Selection Guide

 

 

 

Airports & Transportation

Air quality around airport buildings and gates is often very poor quality. Many of the service vehicles and auxilary power units are powered by diesel engines which generate particulate and NOX gases. GVS have a range of products to deal with these challenges and satisfy EN13779 indoor air quality standards. GVS are fast becoming the default filter manufacturer for airports. Contact us for further information and details of recent projects we have undertaken.

 

  

 

Commercial & Retail

Commercial and Retail buildings are often located in built up areas where outdoor air quality is already at a low quality level. Air is often polluted with PM10 and PM2.5 particles, diesel particulate, building dust and NOX gases. Without proper filtration the long term exposure to these pollutants, particularly when re-circulated throughout buildings, can have damaging effects on their occupants.  GVS have a wide range of filters designed to cope with these challenges as well as reducing energy consumption within a building.

 

  

 

Hospitals

Air quality has significant impact on patient outcome. Hospitals are very focused on reducing the number of infections due to physica contact. A similar effort needs to be made with air quality. It has been shown that something a simple as upgrading filters can reduce the number of people infected wth certain diseases which in turn has an impact on recovery times and patient costs. GVS have a number of products including the Bacticell which improve air quality by allowing increased air flow and reducing pathogens through anti-bacterial coatings.

 

 

 

Hotels & Hospitality

Indoor air quality impacts on a large number of areas within the hospitality business. From kitchen areas where a lack of extract cleaning it can pose a genuine threat to the safety of a building through to spa and pool areas where increased humidity damages decoration or can lead to risks of legionella. GVS can advise how best to maximise air quality and minimise costs of filter changes. With our range of energy saving and anti-microbial filters it is often possible demonstrate savings in energy saving through changes in specification that outweigh the cost of replacing filters.

 

 

 

Leisure Centres

Leisure centres, spas, gyms and hotels with pools have unique challenges to deal with for HVAC. The higher levels of humidity and the air changes needed to deal with the moisture mean standard filters are not suitable. In addition, the risk of bacterial growth or legionella poses a threat to both staff and customers. It is important that facilties management teams be mindful of these risks when specifying filters and managing changes. GVS have experience specifying, changing and disposing of filters in these environments as well as filter solutions such as the Bacticell with imprgnated antibacterial coatings to ensure the air remains at an acceptable quality level and it's occupants are not put at risk.

 

 

 

Museums & Art Galleries

Most museums and art galleries are located close to areas with high traffic pollution. The increase in diesel vehicles in recent years has caused a specific problem for museams and galleries as the NOX fumes and diesel particulate cause serious damage to both the exhibits and the decoraton of the building. GVS have HVAC  filter products that can bring the particulate down to safe levels as well as molecular filtration products that can remove the gaseous contaminant.

 

 

 

Industrial & Pharmaceutical

Complex electronic, pharmaceutical or food processing facilities require high levels of efficient filtration in order to keep processes reliable and safe. GVS manufacture a range of HEPA filters in house to EN1822:2009. These HEPA filters are produced with unique barcodes to ensure raceability from material sources down to individual filter units. It's this level of quality that ensures that GVS are fast becoming one of the market leaders in HEPA filtration.

 

 

 

The GVS Filter Range  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Appliance Filtration Guide

GVS has over 25 years experience in appliance air filtration and product design. This experience includes research and development, prototyping, verification testing, automated production and validation to supply market leading air filters that give outstanding performance.

Particulate filters including pleated filters, pads and pre-filters are used in many different applications. They are designed and specified depending on their intended use, with the following characteristics which we can tailor:
• Filter life expectancy
• Filtration efficiency
• Filtration resistance
• Operating temperature range
• Electrostatic charge to improve efficiency
• Filter washability, with airflow recovery charactersistics (ARC)
• Sound attenuation to reduce operating noise levels in machines
• Anti-microbial properties to protect against bacteria and viruses
• Combined use with another filtering element to enhance its performance.
• Remove specific particle sizes; Pad & pre-filters can protect against larger particles whilst pleated filters can protect against particles from sub 0.1micron up to 10 microns
• Loading capacity for specific particle sizes; Pad & pre-filters can provide greater loading capability at larger particle sizes.

Particulate filters can be classified according to EN1822:2009 for specifying filtration efficiency in operation.
EPA, HEPA and ULPA filters are used to provide the highest levels of air purity, which range from E10 - 85% to U17 - 99.999995% efficiencies. HEPA and ULPA filters are also subject to individual tests with testing based on the latest particle counting methods.
Particulate air filters are constructed from specialist materials such as glass-fibre, synthetic non-wovens, ePTFE membrane and cellulose fibres. These materials are designed to capture particulates such as dust, pollen, mold, bacteria and viruses by interception, impaction and diffusion.
Pleated particulate filters are constructed from high performance air filtration media, which is pleated to increase the surface area in the required space. The pleating method and pleat design is calculated to optimise the filter and to get the best filter performance, meeting and surpassing customer requirements. Non standard and unique customer specific designs can be supported and developed by the GVS Air Filtration engineering team.

Additional components can be incorporated into the filter to improve performance and function, for example:
• Clips
• Threaded inserts
• Gaskets and seals
• Pre-filters and scrims
• Protective grills or mesh
• Disposable or replacable covers
Graphics, text and information can be applied to the filter by a variety of methods such as printing, vinyl labels, ink-jet or incorporated into an injection mould tool.
Additionally, filters can be numbered individually or in batches if required and can include instructions for use and certificates of conformity when required.

Customer Specific Design & Innovation

Innovation from research and development is the core philosophy of our business. We constantly research and develop novel and innovative manufacturing techniques, carry out investigations and develop cutting edge filtration media, with state of the art filtration testing equipment and methods.
We are always ready to provide solutions for you, using new ideas and concepts, which push the boundaries of filtration technology.

Air Filtration Contaminants Guide

The below chart lists a number of common types of airborne contaminants, both particulate and fumes.

 

GVS Carbon / Contaminants Selection Chart

 

Mask Filter Selection Guide

Employers are recommended to conduct a formal risk assessment on exposure to airborne contaminant and to refer to relevant guidance within their industry or health and safety authorities to determine the level of respiratory protection required.
This general guide is based on the European standards that must be reached to attain certification and classification of masks.
Certification demonstrates that the mask is suitable for protection against known contaminants.
Determining what classification of mask is required is based on regulation or guidance at governmental or industry level.
The information in this guide, and others in its series, is not exhaustive, and while sources for further information are provided, guidance, recommendations and regulations may vary between countries.

Choose the right mask/filters for your applications or hazards exposure

Face Fit Testing

Face fit testing is the method used to ensure that a face mask is correctly fitted so that there is no inward leakage of unfiltered air via the edges of the mask. The objective of the test is to confirm that the wearer knows how to correctly fit the mask by adjusting the straps as well as to validate its performance on the user. BS EN 529 defines the steps to be taken to assess a potential hazard, the necessity for respiratory protection and the type of testing recommended.

There are two types of test:
Qualitative - This test is conducted using a hood over the mask wearer into which a bitter/sweet odour is injected. If the mask wearer can taste or smell the odour, the mask requires adjustment. While useful, it is purely subjective as perceptions can differ between subjects undertaking the test.

Quantitative - Provides a numerical measure of the effectiveness of fit - a Fit Factor. This test istypically carried out using a particle counting device or a controlled negative pressure device.
The test commences by taking a count of the number of ambient particles leaking into the facepiece and compares this with the particle number challenging the facepiece while the wearer carries out a number of specified exercises.

There are a number of devices available on the market for employers to use to conduct either Qualitative or Quantitive face fit tests. In addition independent testers can be contracted.

European Filter Classes

The primary determining factor in designating the classification of a face mask are the air filters fitted. The Elipse range commences with a P3, the highest grade for the removal of PARTICULATES, MISTS, FUMES (water and oil based).
Particulates are dusts, the ‘3’ indicating the size of dust in the test standard and efficiency with which the filters will remove it.
Air filters may also combine a PARTICULATE filter with an ACTIVATED CARBON filter to provide the additional capability to remove gases, vapours and odours. The type of activated carbon will vary as some types are more effective than others at removing known gases.
The table below illustrates the European Standards and Markings for Respiratory Protection. The ‘colours’ denote that which should be present on the air filter casing to signify that it is suitable to remove the contaminant.

 

Face Mask Protection Factors

The European system for determining the grade of mask required to protect against a given contaminant is based on BS EN 529 Respiratory protective devices.

Contaminants Guides

In order to ensure safe and effective performance of your filration system it is vital to specify the correct product based on the known contaminants. On the left are links to a guide that helps you make the selection.

TERMINOLOGY: GLOSSARY

 

A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z

 

A

 

ABRASION, FLEX
Fabric wear in a creased area caused by excessive bending, usually associated with cage contact used in baghouse filtration.

 

ABRASION RESISTANCE
Ability of a fiber or fabric to withstand surface wear.

 

ABSOLUTE
A degree of filtration that guarantees 100% removal of suspended solids over a specified size found in the filtrate.

 

ABSOLUTE PRESSURE
The pressure above an absolute vacuum. One atmosphere (14.7 psi) greater than gauge pressure. Symbolized as psia when the pressure is in psi units.

 

ABSORPTION
The taking in, incorporation or reception of gases, liquids, light or heat. Penetration of one substance into the inner structure of another, using filling the void of the matrix. The process of movement of a drug from the site of application into extracellular compartment of the body.

 

ACTIVATED CARBON
Charcoal activated by heating to 1472-1652ºF a material of high adsorptive gases, vapors, organics, etc. Has a large internal surface area. Removes dissolved color, odor and taste from liquids or gases. Commonly used in the pharmaceutical industry to remove organic contaminants.

 

ACTIVATED SLUDGE
Biologically active floc from aeration and settling sewage and/or organic matter.

 

ADSORPTION
The adhesion of a substance to the surface of a solid or liquid. Adsorption is often used to extract pollutants by causing them to be attached to such adsorbents as activated carbon or silica gel.

 

AEROBIC BACTERIA
Organisms requiring oxygen to live.

 

AEROSOL
A dispersion of small liquid or solid particles suspended in air, gas or vapor.

 

AIR FLOW
Measure of the amount of air that flows through a filter, a variable of the degree of contamination, differential pressure, total porosity and filter area. Commonly expressed in either cubic feet/minute/square foot or liters/minute/square centimeter at a given pressure.

 

AIR STANDARD
Dry air at 70 degrees F and 29.92" mercury pressure.

 

AIR-TO-CLOTH (A/C) RATIO
The ratio of gas volume (acfm) to effective cloth area (sq. ft.). In SI units A/C = m3/m2.

 

AMBIENT
Refers to common environmental conditions in which experiment is conducted.

 

AFFLUENT
Fluid entering the filter or filter system. Commonly described as influent, it is the opposite of effluent.

 

AGGLOMERATION, PARTICLE
Multiple particles joining or clustering together by surface tension to form large particles, usually held by moisture, static charge or particle architecture.

 

ALKALINITY
The capacity of water to neutralize acids, a property imparted by the water's content of carbonates, bicarbonates, hydroxides and occasionally borates, silicates and phosphates. It is expressed in milligrams per liter of equivalent calcium carbonate.

 

ANAEROBIC
Organism capable of growing without the presence of oxygen.

 

ANGSTROM
A unit of length 10-10 meter used to express wave lengths. Used in measurements of RO filtration in the ionic range.

 

ANTISTATIC
A condition inherent in or applied to a material usually fabric or plastic, which results in a significant reduction in or the absence of electrical charges. (an electrical resistivity of ~10-10ohm/square or higher.

 

AQUEOUS
Similar to or resembling water. Referring to solution made in water.

 

ARIZONA ROAD DUST
Standardized test dusts for both liquid and air classified from natural Arizona dust generally referred to an A.C. Fine and A.C. Course Dust. Both dust materials also carry an ISO designation and have a standardized size distribution of particles.

 

ASHRAE
American Society of Heating, Refrigerating, and Air Conditioning Engineers.

 

ASYMMETRIC MEMBRANE
A membrane in which the pore size and structure are not the same from one side of the membrane to the other. These membranes are usually considered directional because of difference in flow characteristics depending on which side of the membrane faces the feed stream.

 

ASME
American Society of Mechanical Engineers. Published code, which governs the design of pressure housings.

 

ASSAY
Analytical procedure to determine purity or concentration of a specific substance in a mixture.

 

AUGMENTATION
In fabric air filtration, the imposition of an electrical field to the collecting surface and.or subjecting the incoming particulate matter to a charging process.

 

AUTOCLAVE
A chamber for sterilizing with saturated steam filters or equipment by using constant high temperature and pressure.

 

 

 

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B

 

BACKPRESSURE
A backward surge of pressure from downstream to upstream of the filter. Can be the result of closing a valve or air entrapped in a liquid system.

 

BACKWASH
Reversal of a fluid flow through the filtration media to remove solids from the filter. To clean or regenerate a filter.

 

BACTERIA
Free living simple celled, microscopic organisms having a cell wall, lacking a defined nucleus, shape and round, rod-like, spiral or filamentous.

 

BACTERIAL CHALLENGE
Testing the bacterial retention of a filter.

 

BAGHOUSE
An air filtration structure utilizing fabric filter bags for the purpose of removing solid particulate from the gas stream.

 

BAG LIFE
Time a bag filter performs effectively.

 

BAR
Unit of pressure. 1 bar = 250Pa = 14.5 psi.

 

BARREN LIQUOR
Liquor for cake washing, which contains little to no valuable liquor; as barren cyanide solution in gold cake slimes washing.

 

BASKET
Element of a basket strainer. Normally uses a screen as a medium for removal of course bulk solids.

 

BELT FILTER PRESS
Akin to a rotary drum and belt filter is an automatic pressure filter, where sludge is compressed on an endless rotating belt, dewatering and providing for very dry cake for discharge.

 

BETA RATIO
Measurement of filter retention efficiency. Ratio of particles exposed to a filter, as a feed stream to the particles down stream (filtrate).

 

BIAXIALLY STRETCHED MEMBRANE
A microporous membrane from either polypropylene or PTFE that has been stretched in both the MD and CD direction in a manner to form pores of a controlled size and possessing a narrow pore size distribution.

 

BIOBURDEN
The load or level of microorganisms in a substance to be filtered.

 

BIOHAZARD
Biological refuse, possibly pathogenic in nature.

 

BIOSAFETY
Biological safety or non-toxicity of a substance to a living organism. For filters used in health care applications.

 

BIPOLAR
Have two (opposing) poles, (+) and (-) as applied to ionic charges or particles.

 

BROWNIAN MOTION
The continuous zigzag motion of suspended minuscule particles. The motion is caused by impact of the molecules in the fluid upon the particles.

 

BLINDING
Blockage by dust, fume or liquid not being discharged by the cleaning mechanism, results in a reduced gas or liquid flow of increased pressure drop across the filter media.

 

BLOWDOWN
The use of pressure to remove liquids and/or solids from a vessel.

 

BREAKTHROUGH
Used to describe the passing of solids through the cake build up of a filter medium. Also called breakpoint.

 

BRIDGING
Material or particulate blockage across an opening, often of a pore or filter medium.

 

BUBBLE POINT PRESSURE
A test to determine the maximum pore size openings of a filter. The differential gas pressure in which a wetting liquid (e.g. water) is pushed out of the largest pores and a steady stream of gas bubbles are emitted from a wetted filter under specific test conditions. A filter integrity test with specified, validated pressure values for specific pore-size and type filters.

 

BURST PRESSURE
The pressure causing rupture. The inside-out differential pressure that causes outward pressure on the structural of a filter medium, filter or housing.

 

 

 

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C

 

CAKE (FILTER)
Solids deposited on the filter media. In many cases the cake may serve as its own filter medium.

 

CAKE RELEASE
Ability of a medium to allow clean separation of the cake from the medium.

 

CALENDERING
A manufacturing process where woven and/or nonwoven fabrics are pressed between heavy rollers compressing the fibers. The process reduces the filter medium void volume, pore size rating, flow-rate and dirt-hold capacity of the medium.

 

CANDLE FILTER
A reusable filter consisting of a tube made from ceramics or metal. Flow is from the outside-in with particulate accumulating on the outside of the candle. The candle can be cleaned by various means, including back-pulsing, heat, chemicals etc.

 

CAPACITY
Volume of product which a housing will accommodate expressed in gallons or similar units. Also, amount which will filter at a given efficiency and flow rate, expressed in gallons per minute or similar units.

 

CAPSULES
Disposable devices which have an integrated filter and housing, including inlet and outlet.

 

CARTRIDGE
Filter devise and medium used in a housing to perform the function of coalescing, filtration or separating. Also referred to as an element.

 

CATHODE
Negative pole or electrode of an electrolytic system.

 

CAUSTIC
A class or name given to a class or group of chemicals, usually soda or sodium hydroxide.

 

CD
Refers to the "cross-machine" manufacturing direction of filtration roll stock.

 

CELLULOSE
(1) fibers used to manufacturer wetlaid paper (2) used as a filter aid in highly refined alpha cellulose form or as the slightly more unbleached form.

 

CENTER CORE or TUBE
Material formed into a cylinder shape for structural purposes to permit a cartridge to retain its original physical form.

 

CENTER PIPE or ROD
Component of a housing which is used as a mount for cartridges, typically through the center core.

 

CENTRIFUGATION
Separating two substances of differing densities by high speed spinning to create centrifugal force. Generally used to separate suspended particles from liquid.

 

CHROMATOGRAPHY
Separation of substances in a mixture based on their affinity for certain solvents and solid surfaces.

 

CLARIFICATION
Clearing a liquid by filtration, by the addition of agents to precipitate solids, or by other means.

 

CLARIFIER
An apparatus for the removal of settleable solids from a fluid by gravity.

 

CHARGE POLARITY
A particle, fiber or other material carrying an electrostatic charge.

 

CLARIFIER
A processing unit using flocculation processes to separate solids from liquid often in a non-turbulent zone where heavy solids settle out of solution. Often used for wastewater.

 

CLARITY
Amount of contaminate left in a filtered liquid.

 

CLASS 100 ENVIRONMENT
A room environment maintained by air conditioning and filtration so that fewer than 100 particles of size 1 μm or larger are found in a cubic foot of air.

 

CLASSIFICATION
Condition in which larger particle settle out below the finer ones. Also referred to as stratification. May also be referred to as the action to sort out particles by various groups or to other established criteria.

 

CLEANABILITY
The ability of a filter element to withstand repeated cleanings, while maintaining adequate dirt capacity.

 

CLEAN PRESSURE DROP
Differential pressure (drop) across measured in pounds per square inch at rated flow on new elements with clean product.

 

COAGULATION
In water and wastewater treatment, the destabilization and initial aggregation of colloidal and finely divided suspended matter by the addition of a floc-forming chemical or by biological processes.

 

COALESCER
Mechanical device which unites discrete droplets of one phase prior to being separated from a second phase. Can only be accomplished when both phases are immiscible.

 

COALESCING
Action of uniting small droplets of one liquid preparatory to its being separated from another liquid.

 

COATING
Immersion of filter media in a solution to provide the fibers with a coating that will lubricate and thereby reduce self-abrasion.

 

COLD STERILIZATION
Removal of all bacteria by filtration through a sterilizing grade 0.2μm absolute filter.

 

COLLAPSE PRESSURE
The outside-in differential pressure that causes the structure of a filter medium failure of a filter element.

 

COLLECTION EFFICIENCY
Percentage of contaminate collected.

 

COLLOID
Very small, insoluble non-diffusible solid or liquid gelatinous particles that remain suspension in a surrounding liquid. Solids usually on the order of 0.2 μm or less.

 

COMPATIBILITY
Relation to the non-reactivity of filter materials with a substance to be filtered.

 

COMPRESSABILITY
Degree of physical change in filter cake particles when subjected to normal pressures.

 

COMPRESSION BAND
Stainless steel band sewn into the end of a bag to provide a surface to clamp against in the baghouse.

 

CONCENTRATOR
Removes some of the water from a sample to concentrate substances dissolved or suspended in it; usually used to concentrate solutions of biological macromolecules, (proteins & nucleic acids).

 

CONTAMINATE
Unwanted foreign matter in a fluid which is accumulated from various sources such as systems dirt, residue from moving parts, atmospheric solids.

 

CONTINUOUS PHASE
Basic product flowing through a filter or filter separator, which continues on through the system after being subjected to solids and/or other liquid separation.

 

CORE
Commonly refers to a perforated tube, which serves as the center of a filter cartridge (element).

 

CORE YARN
Used in filtration with fiberglass or synthetic yarn. Spun or texturized yarns are twisted around a filament (core) yarn, adding yarn strength and stability.

 

CRITICAL OPERATING PRESSURE
Pressure above which filtration or separation equipment may produce reduced efficiency or fails to function properly.

 

CROSSFLOW (TANGENTIAL FLOW) FILTRATION
A filtration system in which the feed stream flows across the filter media and exits as a retentate stream. The retentate stream is recycled to merge into the feed stream, while a portion of it passes through the filter media, resulting in concentration of the feed stream.

 

CYCLONE
A conical-shaped vessel for separating mixed sized particulates from the gas stream. The vessel has a tangential entry at the largest diameter allowing the larger particles to drop out and be removed from the bottom of the cone while smaller particulate exits overhead with the majority of the gas stream.

 

 

 

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D

 

DE
Diatomaceous earth. A filter aid from diatomite's.

 

DALTON
Measure of molecular mass.

 

DI WATER
De-ionized water; water processed through an ion exchange process by passing through a mixed resin bed to remove positive and negative ions. The purity of water is measured by its electric resistance.

 

DEAD END FILTRATION
Feed stream flows in one direction only, perpendicular to and through the filter medium to emerge as product or filtrate.

 

DEHYDRATION
Removal of water or hydrocarbon in vapor from an air or gas; also water fro0m another immiscible liquid. Differs from entrainment removal in that the dew point of a gas stream will be lowered by vapor removal. A form of purification.

 

DENIER
The weight in grams of 9,000 meters of a fiber.

 

DENSITY
Mass/unit volume, usually expressed in g/cc, lb./cu. ft or lb./gal.

 

DEPTH FILTRATION
A process that entraps contaminants both within the matrix and on the surface of the filter media.

 

DESALINATION
Production of fresh (potable) water from sea water, salt or brackish water by one of several processes, e.g. distillation, flash distillation, electrodialysis or reverse osmosis if salt content is not too huge.

 

DEWATERING
A physical process that removes sufficient water from sludge so that its physical form is changed from essentially that of a fluid to that of a slurry or damp solid.

 

DESICCANT
Drying agent or medium used in dehydration of air or gas or liquids. Examples: silica gel, activated alumina, molecular sieve etc.

 

DIALYSIS
The diffusion of solute molecules through a semi-permeable membrane.

 

DIATOMACEOUS EARTH FILTRATION (D.E.)
A filtration method that uses a medium consisting of microscopic shells of single celled plants known as diatoms.

 

DIATOMITE
Skeletal remains of tiny aquatic plants that lived in the ocean and inland seas millions of years ago.

 

DIFFERENTIAL PRESSURE - Delta (Δ) P
The change in pressure or the pressure drop across a component or device located within the air stream; the difference between static pressure measured at the inlet and outlet of a component device.

 

DIFFUSION
In liquid cake washing, removing the original liquor around the individual particles by mixing with the wash liquor. In air, the particle at a size within one or two orders of magnitude of the gas-flow molecules, moves in Brownian motion and collides with a fiber or other filter media material during its random path of travel.

 

DIFFUSION TEST
A test to determine the integrity of a filter. The test is based upon the transition from diffusional flow to bulk flow of a gas, though a wetted filter.

 

DIFFUSIONAL INTERCEPTION
In gas filtration, at low gas flow velocities, tiny particles are subject to Brownian motion, enabling them to move out of the gas streamlines and become intercepted by the filter.

 

DIFFUSIONAL FLOW TEST
To determine the integrity of a filter. The test is based on the measurement of the diffusional flow of a gas through a wetted filter. Either the gas or the downstream liquid, displaced by the gas, may be measured. The transition from diffusional flow to bulk flow (bubble point) can be determined.

 

DIGESTED SLUDGE
Sludge or thickened mixture of water with sewage solids in which the organic matter has been decomposed by anaerobic bacteria.

 

DIRECT INTERCEPTION
Gas filtration: particles larger than the pores are removed by direct contact with the filter surface. Some particles smaller than pores can be removed as well depending on the proportion to their size hitting the surface.

 

DIRT (HOLDING) CAPACITY
Amount of dirt or debris retained by a filter in grams per unit area of the filter medium.

 

DISCONTINUOUS PHASE
Separated phase or product from the continuous phase. Example: water maybe the discontinuous phase when separated from hydrocarbon, air or gas.

 

DISPERSION
Operation which results in solid or liquid particles entering into suspension in a fluid. Also applies to a two phase system in which one phase, known as the disperse phase, is distributed throughout the other, known as the continuous phase.

 

DISPOSABLE FILTERS
Those filters not cleaned or reused. Referred to as one-time or single-use filters.

 

DISOLVED SOLIDS
Any solid material that will dissolve in a liquid that such as sugar in water.

 

DISTILLATION
Process of vaporizing a liquid and collecting the vapor, which is then usually condensed into a liquid.

 

DMF
Drug Master File. A written document that explains the formulation of an active ingredient, referenced in an Investigational New Drug (IND), New Drug Application (NDA), or Amendment to New Drug Application (ANDA) from a company.

 

DOP
Dioctyl phthalate, a plasticizer that can be aerosolized to particles of extremely uniform size. Retention of DOP aerosol is used as standard procedure for pore size rating of air filters. Typically, 99.97% DOP retention indicates HEPA efficiency.

 

DOWNSTREAM SIDE OF FILTER
The filtrate or product stream side of the filter. Fluid and/or solids that have passed through the filter.

 

DRY HEAT STERILIZATION
Sterilization at or above 356ºF using a convection or forced air oven without moisture; may concurrently de-pyrogenate if adequate time and elevated temperature are employed.

 

DRY SCRUBBER
A chemical reaction chamber that neutralizes acids in a gas stream. Two system types: the spray dryer system injects a slurry, whereas dry sorbent injection systems use a dry powder.

 

DUPLEX FILTER
Assembly of two filters with a valve for selection of either or both filters.

 

DUROMTER (SHORE)
Measure of hardness. Must be defined as being either A or D scale.

 

DUST COLLECTION
A term usually associated with an assembly of large pleated elements that collect air-borne particles where large volumes of air flow is found e.g. granaries, cement factories, abrasive production and other
manufacturing facilities.

 

DUST (HOLDING) CAPACITY
Amount of dirt or debris retained by a filter in grams per unit area of the filter medium.

 

DYNE
The amount of force that cause a mass of one gram to alter its speed by one centimeter per second for each second during which the force acts.

 

 

 

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E

 

E. coli
Escherichia coli is the most prevalent bacteria in the gastrointestinal tract of humans and animals. It occurs in solids and water as a result of fecal contamination.

 

END CAP
The end of many types of filter cartridges.

 

ETO STERILIZATION
Chemical sterilization using ethylene oxide at an elevated temperature of 1500 º F and high relative humidity to facilitate permeation of the ethylene oxide into the material being sterilized.

 

EFFECTIVE FILTRATION AREA
The portion of filter that fluid flows through during the filtration process.

 

EFFICIENCY
Degree to which a filter device will perform in removing solids and/or liquids.

 

EFFLUENT
The fluid which has passed through a filter (filtrate or product stream); outflow from other treatment such as wastewater treatment plants.

 

ELECTRETS
A dielectric body in which a state of electric polarization is established. An imposed electric field on heated polyolefin following the drawing stage to form a charged fiber or yarn with electrostatic like properties.
These properties may decay or by contamination by solvents and materials.

 

ELECTROCHEMICAL
A process by which electricity is used to effect chemical reaction. The inter-conversion of chemical and electrical energy.

 

ELECRODIALYSIS
Dialysis (small molecules separated from larger molecules in the same solution/mixture) accelerated by an electromotive force applied to electrodes adjacent to the separating membranes.

 

ELECTROLYTE
Substances which will conduct an electrical current, either in molten state or in a solution e.g. NaCl in water.

 

ELECTROPHORESIS
The separation of charged molecules (such as proteins) based on their mobility in an electrical field.

 

ELECTROSTATICS
Electrical charges on particles and/or fibers in a filter medium create attractive and/or repulsive forces between particles and the fiber/medium. As a direct result, for many types of particles, strong attractive forces produce the intimacy needed to agglomerate even the fines.

 

ELECTROSTATIC PRECIPITATOR
A type of particulate filtration control that attracts charged particles to oppositely charged surfaces to collect airborne particulates. The particles are charged by ionizing the air with an electric field. The charged particles are then collected by a strong electric field generated between oppositely-charged electrodes.

 

ELEMENT
Typically a filter, such as a cartridge, pleated or non-pleated.

 

END CAPS
Components adhered to a filter element with adhesive or other means to contain the filter medium in a form designed for the element.

 

END POINT
Final objective or, in petroleum distillation, temperature at which the distillation ceases.

 

ENDOTOXIN
A toxic substance produced by bacteria, but which is released into the surrounding medium only upon the death or disintegration of the bacteria.

 

ENTRAINED WATER
Discrete water droplets carried by a continuous liquid or gas phase when water is immiscible with the liquid.

 

EPA
Environment Protection Agency regulates environmental monitoring. Establishes and enforces guidelines.

 

EXTRACTABLES
Chemicals leached from a filter during a filtration process; usually tested for by soaking in water under controlled conditions; may be removed by pre-flushing with suitable liquid.

 

 

 

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F

 

FERMENTATION
Enzymatically controlled breakdown of an energy rich compound as a sugar to produce ethyl alcohol, carbon dioxide, and energy, by the action of yeasts which carry the necessary enzymes. Bacterial fermentations also occur.

 

FEED
Materials to be filtered. Also referred to as concentrate, influent, intake, liquor, mud, prefilt, pulp, slime or sludge.

 

FIBER
Any particle with length greater than or equal to 0.5 micron and at least five times greater than its diameter, leaving substantially parallel sides.

 

FIBER METAL FELT
A nonwoven media consisting of extremely fine metal fibers (2-20 micron in diameter) which are compressed and sintered. Used to filter molten polymers in the manufacture of fibers and films and hydraulic fluids for use in aerospace filters.

 

FIBER MIGRATION
Downstream migration of fibers from a filter medium.

 

FILL
Yarns that run in the filling or cross-machine direction of a woven fabric.

 

FILTER
(Noun) A specialized piece of equipment for carrying out filtration, consisting of the filter medium and suitable holder for constraining and supporting the filter in the fluid path.

 

FILTER
(Verb) Passing a fluid containing particles through a filter medium wherein particles are removed from the fluid.

 

FILTER AID
Small size particle substance of low specific gravity which remains in suspension when mixed with a liquid to be filtered. Increases filtration efficiency of a feed when deposited on a septum by forming a porous cake.

 

FILTER CAKE
The accumulation of particulate or solids on a surface. Can also mean a pre-coat for filtering.

 

FILTER EFFICIENCY
A measurement of how well a filter retains particles. The percentage retention of particles of a specific size by a filter.

 

FILTER LIFE
Measure of a filter's useful service life based on the amount of standard contaminate required to cause differential pressure to increase to an unacceptable level, typically 2-4 times it initial differential pressure or 50-80% drop in initial flow or the downstream measure of unacceptable particulate.

 

FILTER MEDIA MIGRATION
Problem caused by a filter medium constructed of a non-continuous or fibrous matrix. Portions of the filter change structure causing fibers to migrate downstream.

 

FILTER MEDIUM
Permeable material that removes particles from fluid being filtered.

 

FILTER PAPER
A permeable web of randomly oriented fibers, generally cellulose or glass fiber formed from water draining from a suspension fed in a paper making process. Also, a presentation at a filtration conference.

 

FILTER PRESS
Mechanical process where wet solids are compressed between two or multiple surfaces in the same equipment forcing water out of the solids, simultaneously compacting and drying the cake.

 

FILTRATE
The end product of the filtration process. The liquid exiting the filtrate outlet.

 

FILTRATION
Removal of particles from a fluid by passing the fluid through a permeable material.

 

FILTRATION RATE
The volume of liquid that passes through a given area of filter in a specific time.

 

FINES
Portion of a powder like material composed of particles smaller then the size specified.

 

FLOW DECAY
Decrease in flow rate caused by filter plugging or clogging.

 

FLOCCULATION
Growing together of minute size particles to form larger ones, called floc's.

 

FLOW DECAY TEST
Determines flow rate and throughput of a filter type or combination of filters on a specific liquid, usually by using small area filters, to determine the sizing of a filter system.

 

FLOW FATIGUE RESISTANCE
The ability of a filter element to resist structural failure of the filter medium due to flexing caused by cyclic differential pressure.

 

FLOW RATE
The speed at which a liquid flows and is measured in gallons or liters per minute. Flow rate of a liquid can be affected by the liquids' viscosity, differential pressure, temperature and type of filter used. Measuring air
diffusion.

 

FLOW RESISTANCE
Resistance offered by a filter medium to fluid flow.

 

FLUE GAS DESULFERIZATION
The operation of removing sulfur oxides from exhaust gas streams of a boiler or industrial process. Usually a wet scrubber operation.

 

FLUID
Includes liquids, air or gas as a general term.

 

FLUX
Measure of the amount of fluid that flows through a filter, a variable of time, the degree of contamination, differential pressure, total porosity, viscosity and filter area.

 

FLY ASH
The air borne combustion residue from burning coal or other fuels.

 

FORWARD FLOW TEST
An integrity test measuring air diffusion at a low pressure (approximately 5 psi). Similar to a pressure hold test.

 

FRAZIER PERMEOMETER
Porosity testing device. The normal measurement is air flow in CFM passed through one square foot of fabric at 0.5 inch differential water pressure.

 

FULLERS EARTH
Medium used in some elements, usually a blend of attapulgus and montmorillonite clay. A finely divided hydrous aluminum silicate. Often a filter aid.

 

 

 

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G

 

GAUGE PRESSURE
Pressure measured by a pressure gauge. Pressure above ambient pressure when the pressure is used in psi units.

 

GELATINOUS
Used to describe suspended solids that are slimy and deformable, causing rapid filter plugging.

 

GMP's
Good Manufacturing Practices. Food and Drug Administration regulations governing the manufacture of drugs. Sometimes referred to as CGMP's.

 

GRADIENT DENSITY
A stratified cross-section. Used to describe a filter medium where larger pores are at the upstream side of the medium with finer pores downstream. The configuration increases dirt-holding capacity and improved filter life. The medium may be inverted when a surface filter effect is desired resulting in lower differential pressure across the medium than if the medium has a single density throughout..

 

GRAVITY FILTER
Filter in which the driving force for filtration is provided solely by the head of liquor above the filter medium.

 

GRAVITY SEPARATION
Separation of immiscible phases resulting from a difference in specific gravity by coalescing.

 

GURLEY TEST
Measure of time required to expel 100 cc's of air though a filter medium placed within an apparatus that can be fitted with a selection of office sizes and weights. Historically used for paper products and more recently for microporous membranes. (ASTM: D-726).

 

 

 

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H

 

HVAC FILTERS
Air filters used in heating and air conditioning locales.

 

HEAVY METAL
Metallic elements having a high density (> 5g/cm5 ), toxic for the most part.

 

HEPA
An air filter or medium, which captures 99.97% when challenged with DOP 0.3 micron particles under certain laboratory controlled conditions.

 

HIMA
Health Industry Manufacturer's Association defines and sets standards governing the validation of filters for sterilizing liquids. . . a trade association, whose membership includes pharmaceutical manufacturers and filter manufacturers.

 

HOLDING CAPACITY
See Dirt Holding Capacity above.

 

HOUSING
A metal or plastic tank or tube with an inlet and outlet containing a filter (s), allowing for the flow of a fluid and contaminate through the filter, while containing the process.

 

HYDROPHILIC
Water accepting or wetting.

 

HYDROPHOBIC
A membrane or other material which repels and cannot be wetted by aqueous and other high surface tension fluids. When pre-wetted with low surface tension fluid, such as alcohol, the filter will then wet with water.

 

HYDROMETER
An instrument used to measure the density of a liquid.

 

 

 

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I

 

IMMISCIBLE
Incapable of being mixed; insoluble.

 

INERTIAL IMPACTION
Gas filtration: Retention mechanism. Inertial Collection. As the gas stream lines bed in the vicinity of the filter, the carried particles continue in a straight line due to their inertia and impact the filter. Effective primarily for particles about 0.3μm and larger, at high gas velocities and low filter porosity.

 

IMPERMEABLE
Material that does not permit fluids to pass through.

 

IMPINGEMENT
Process of removing liquid or solid contaminate from a stream of compressed air or gas by causing the flow to impinge on a baffle plate at high velocity.

 

INFLUENT
Fluid entering the filter.

 

IN-LINE FILTER
A filter assembly in which the inlet, outlet & filter element are in line.

 

INERT
Chemical inactivity; unable to move; totally un-reactive.

 

INTERIAL IMPACTION
The particle, due to its inertia and usually in stream-line flow, deviates out off the air/gas stream striking a fiber or other material of a filter medium.

 

INLET PRESSURE
Pressure entering the inlet side of the filter. Also called upstream pressure or line pressure.

 

INORGANIC MATTER
Chemical substances of mineral origin, not containing carbon to carbon bonding. Generally structured through ionic bonding.

 

IN-SITU
Sterilization or integrity testing of a filter in the system rather than as an ancillary operation such as in autoclave or bubble point stand.

 

INTEGRITY TEST
Used to predict the functional performance of a filter. The valid use of this test requires that it be correlated to standardized bacterial or particle retention test. Examples: Bubble Point Test, Diffusion Test, Forward Flow Test, Pressure Hold Test.

 

INTERFACIAL TENSION
Measure of miscibility or solubility of the continuous and discontinuous phases. Increases as miscibility or solubility decreases.

 

INTERSTICES
Spaces or openings in a filtration medium. Also referred to as pores or voids.

 

INTERSTITAL
Pertaining to the openings in a filtration medium.

 

IN-VITRO
In isolation from living organisms in an experimental artificial environment e.g. cells in tissue culture; experiments carried out in test tubes.

 

IN-VIVO
Within the living organism.

 

ION(S)
An atom or group of atoms that carries a positive or negative electrical charge as a result of having lost or gained one or more of the electrons.

 

ION EXCHANGE COLUMNS
Vessels filled with ion exchange resin (anion, cation, or mixed) for producing conditioned or DI Water. Also, type of column used for Ion Exchange Chromatography.

 

ISOTROPIC (SYMMETRIC) MEMBRANE
Membrane in which the pore openings are the same diameter throughout the thickness and on both sides of the membrane. Non-directional, their flow characteristics are independent of which side faces the feed stream.

 

 

 

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K

 

KNIFE EDGE SEAL
Narrow, pointed ridge on the sealing surface of an
end cap, center seal or cartridges adaptor which provides a seal by
biting into the cartridge gaske

 

 

 

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L

 

L-TYPE FILTER
Cartridge filter in which the inlet and outlet port axis are at right angles and the filter elements axis is parallel to either port axis.

 

LAMINAR FLOW
Term synonymous with streamline flow and viscous flow. A flow regime which the flow characteristics are governed mainly by the viscosity of the fluid.

 

LEAF
Any flat filter element that has or supports the filter septum.

 

LEAF FILTER
A filter housing and device consisting of a plurality of leaves, often place in a vertical position.

 

LINE PRESSURE
Inlet pressure, upstream pressure. The pressure in the supply line.

 

LIQUOR
Material to be filtered. Also referred to as concentrate, feed influent, intake mud, prefilt, slime or sludge.

 

LIVE STEAM STERILIZATION
Sterilization by flowing saturated steam through a vented vessel or system, usually at 257ºF and 20 psi (Can be performed up to 284ºF and 35 psi.).

 

LOADED
A filter element that has collected a sufficient quantity of insoluble contaminates such that it can no longer pass rated flow without excessive differential pressure.

 

LOCK UP
Device that will lock either a column, elements or the body of a housing in place.

 

LOG REDUCTION VALUE
The logarithm to the base of 10 of the ratio of organisms in the feed to the organisms in the filtrate. Example: Log 1o [10 9/101.7] = 7.3. Also used as a ratio of in/out bioburden in other sterilization methods such as autoclaving.

 

LOW INTERFACIAL TENSION
Where the interfacial tension of one liquid over the other liquid would be less than 25 dynes/cm at 70 degrees F.

 

LOX CLEANING
Process of cleaning for liquid oxygen service.

 

LVM
Low volatile material.

 

 

 

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M

 

MANOMETER
A U-shaped tube filled with a specific liquid. The difference in height between the liquid in each leg of the tube gives directly the difference in pressure on each leg of the tube. Used to monitor differential pressure.

 

MARTIN'S DIAMETER
Statistical diameter used in particle size analysis; the mean length of the line, parallel to the microscope traverse, diving each particle into two equal diameters.

 

MASS DISTRIBUTION
Relative frequency distribution of mass within a particle size distribution. Sometimes presented as cumulative percentage undersize.

 

MASS TRANSFER RATE
Measurement of the movement of matter as a function of atoms etc.

 

MD:
Refers to the "machine-direction" when manufacturing filtration roll stock.

 

MEAN EFFICIENCY RATING
The measurement of the average efficiency of a filter medium using the Multi-Pass Test where the average filtration (BETA) ration equals 2.0.

 

MEAN FLOW PORE MEASUREMENT
It is calculated as the diameter of the pore of a membrane partially voided of liquid such that air flow of the partially wetted membrane is equal to 1/2 the dry air flow. (Theoretical diameter of the mean pore).

 

MEDIA
Material through which fluid passes in the process of filtration and retains particles. Also, nutrients containing solutions in which cells or microorganisms are grown.

 

MEDIA MIGRATION
Migration of materials making up the filter medium may cause contamination of the filtrate.

 

MEDIUM
Principle component of a filter element. Material of controlled or uncontrolled pore size or mass through which a fluid stream is passed to remove foreign particles held in suspension or to repel droplets in the case of coalesced water.

 

MELTBLOWN
A nonwoven manufacturing process for filtration media, where a molten polymer is extruded out of an orifice with high-velocity air to create fine fibers. The fibers can create roll stock or be spray-spun onto porous tubes to create a finished filter.

 

MEMBRANE
Media through which a liquid is passed; usually associated with an extremely fine or tight type of filtration. Highly engineered thin polymeric film containing a narrow distribution of pores. Used as the separation mechanism in R/O, Electrodialysis (ED), Ultrafiltration (UF), Nanofiltration (NF) & Microfiltration (MF).

 

MEMBRANE FILTER
Continuous matrix with fine pores of defined size or a film allowing for the diffusion of a fluid through its structure; sometimes referred to as a dense film in the case where no pores are present.

 

MERV (Minimum Efficiency Reporting Values) Rating
A system for rating air filters according to their average particle size efficiency on a scale from 1-16 with 16 being the highest capture efficiency for average particles in the 0.3 to 1.0 micron range. The rating is derived from a test method developed by the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE).

 

MESH
A term referring to a woven filtration medium, typically wire cloth or monofilament woven fabric.

 

MESH COUNT
Number of openings or fractions of openings in a lineal inch of wire cloth or monofilament woven fabric.

 

MICRON (μm)
The common unit of measurement in the filtration industry is the micron or micrometer. One micron equals forty millionths of an inch (0.00004) or expressed differently 25.4 microns equals 0.001 inch.

 

MICRON RATING
The smallest size of particles a filter can remove.

 

MICROFILTRATION (MF)
Used for clarification, sterilization, to detect or analyze bacteria and other organisms and particulate matter. Separation of particles ranging from 0.1μm to 10μm.

 

MICROMETER (m)
Micron, 1/1,000,000 of a meter. 60gm is approximately the diameter of a human hair.

 

MICROPOROUS MEMBRANE
Thin polymeric films (e.g. 0.001 to 0.005" thick) often with millions or pores per square inch, aligned as a torturous path, allowing for the passage of a fluid to remove solids. Often used for sterilizing filtration and other fine filtration purposes. Considered a surface filter medium.

 

MIGRATION
Contaminate released downstream of a filter.

 

MIL
One thousandth of an inch.

 

MINIMUM BUBBLE POINT PRESSURE
It is a diffusional flow pressure just before the onset of bulk flow. Minimum critical bubble point pressure: a filter specification derived from diffusional flow, bubble point curves for many filters.

 

MISCIBLE
Capable of being dissolved. Opposite of immiscible.

 

MIXED CELLULOSE ESTERS
Synthetic materials derived from naturally occurring cellulose. Materials used in the manufacture of membrane filters. Mixed cellulose esters membranes are used in a wide variety of applications, such as bacteria concentration in water analysis and air sampling.

 

MOLARITY
The term used to indicate the concentration of dissolved substance in a given solution. The measurement is in moles of dissolved substance per liter of solution.

 

MOLECULAR WEIGHT
Sum of the atomic weights of all atoms in a molecule. Also, Mole or Mol weight.

 

MOLECULAR SIEVE
Zeolite, natural or synthetic or similar materials where atoms are arranged in a crystal lattice in such as way that there are a large number of small cavities interconnected by smaller openings or pores of precise uniform size. Used as a drying agent or for absorptive applications.

 

MONOFILAMENT
Single, large continuous filament of a synthetic yarn. Similar to fishing line in cross-section.

 

MONOFILAMENT WOVEN FABRIC
Woven fabric from monofilament yarns used as a screen or surface filter. Often used in sifting, belting, medical filters etc. Most common yarns are from polyester, polypropylene and nylon.

 

MUD
Material to be filtered.

 

MULLENS BURST TEST
A formal measurement where test specimen (filtration medium) sees a force, which cause it to burst.

 

MULTIFILAMENT
A number of unbroken continuous fiber stands that run parallel to form a yarn. Typically used to manufacture a woven or knit fabric.

 

MULTI-PASS
A test system designed to be representative of a typical hydraulic or lubricating circuit. Fresh contaminate is introduced in slurry form into a test reservoir, mixed with the fluid in the reservoir and pumped through the test filter; contaminate not captured by the filter is returned to the reservoir for another pass (or more) though the filter.

 

 

 

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N

 

NEEDLEFELT
A nonwoven fabric where staple fibers are entangled together through a manufacturing process using barbed needles, providing for a heavy weight filter fabric, which can filter air-borne particles for use in baghouses and suspended particles in liquids from lighter weight needlefelt fabrics for use liquid bag filtration.

 

NFR
Non-fiber releasing. A filter or medium, which will not release fibers into the filtrate.

 

NIOSH
Develops basic methodology for analytical test procedures. National Institute of Occupational Safety and Health.

 

NOMIMAL
An arbitrary term used to describe the degree of filtration and generally not comparable or interchangeable between products or manufacturers. A user should always ask for a copy the test procedure used and results from the manufacturer's lab notebook to understand each rating.

 

NOMINAL FILTRATION RATING
An arbitrary micrometer value indicated by the filter manufacturer. The same ratings from two manufacturers are often different and rarely can be compared.

 

NONPOLAR
Compound or element that's electron capacity is satisfied. A neutral condition that will remain un-reactive. Not polar. See Polar.

 

NONWOVEN
A filter fabric that is formed of natural or synthetic fibers that are randomly oriented in filtration media. Typically, held together with a binder or fibers are entangled.

 

NYLON
When used as a membrane it is hydrophilic. A thermoplastic, polymeric material that has high mechanical strength & compatibility with different chemicals.

 

 

 

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O

 

OPEN AREA
Pore area of a filter medium, often expressed as a percentage of the total area.

 

OSMOSIS
Diffusion of a liquid through a semi-permeable membrane from a dilute solution into a more concentrated solution, thus tending to equalize the concentration of each side of the membrane.

 

OUTLET PRESSURE
Downstream pressure. Pressure exiting the outlet side of the filter.

 

 

 

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P

 

PACKED BED
Discrete particles such as sand, gravel, anthracite, fabricated rings or saddles, assembled in a confined space as a filtration medium for liquids and gases.

 

PAPER
Filter medium used on filter elements. A general term applied to resin bonded cellulose.

 

PARALLEL FILTRATION
Branching a filtration setup. Two assemblies of the same pore size are in parallel, to increase flow rate or simplify filter changes.

 

PARTICLE
Unit of material structure; a mass having observable length, width, thickness, size and shape.

 

PARTICLE COUNT
Practice of counting particles of solid matter in groups based on relative size contained in a certain area.

 

PARTICLE SIZE DISTRIBUTION
The size range and quantity of particles which are measurable in a dry or liquid sample. Used to determine the appropriate filter media for a specific process.

 

PARTICULATE
Any solid or liquid material in the atmosphere.

 

PARTICULATE UNLOADING
The process whereby a filter, particularly, a depth filter, can become blocked with particulate matter and subsequently release part of this matter downstream.

 

PERISTALTIC PUMP
A pump functioning by alternate pinching and release of tubing which drives the fluid forward in a pulsing action. The pump is noninvasive. Only the inner wall of the tubing contacts the fluid.

 

PERLITE
Material similar to volcanic glass with a concentrated shell structure. Used as a filter aid.

 

PERMEABILITY
A measure of fabric porosity or openness, expressed in cubic feet of air per minute per square foot of fabric at a 0.5" water column pressure differential in air or by specified conditions for liquid.

 

PERMEABLE
Material that has openings through which a liquid or gas will pass in filtering.

 

PERMEATE
The fluid which passes through a membrane, a term usually used with ultrafiltration or R/O.

 

pH
Measure of a substance's acidity or alkalinity from 1-14 with 7 being neutral. Measure of hydrogen ion concentration.

 

PHASE
May be continuous, as the basic product flowing through a housing or discontinuous as the material to be removed from the basic product. Both are distinct and separate.

 

PHENOLIC RESIN
Synthetic thermosetting resins obtained by the concentration of phenol and substituted phenols with aldehydes. Used as a binder in cellulose and glass fibers for form filter media.

 

PLASTISOL
Suspension of a thermosetting plastic which can be molded into a desired shape. Used as a combination end cap and gasket on an element.

 

PLEAT SUPPORT/SPACERS
Used to prevent the collapse of pleats in a pleated paper or membrane cartridge when under the action of differential pressure.

 

PLEATER
Automated equipment that folds a filter medium roll stock vertically for subsequent incorporation into a filter element. Provides for greater media surface area in a limited space. There are many types of pleaters, including pusher bar, rotary etc.

 

PLUGGING
Filtered out particles filling the openings (pores) in a medium to the extent of shutting down the flow of a fluid. Also referred to as blinding or blocking.

 

POINT-OF-USE FILTERS
Filters located immediately prior to where a clean effluent is required in a process.

 

POLAR
Compound or element capable of receiving or giving electrons. See Non-Polar.

 

POLYELECTROLYTE
Synthetic, water-soluble, linear polymers characterized by the presence of ionizing groups distributed along a molecular length. Used to promote flocculation.

 

POLYPROPYLENE
A thermoplastic polymeric material, resistant to a broad range of chemicals. When used as a membrane, polypropylene is hydrophobic.

 

POLYSULFONE
Has excellent flow rates, high mechanical strength, resistant to a broad range of temperatures, can be sterilized and is hydrophilic. Commonly used membrane material, but is not resistant to many organic solvents.

 

PORE
Opening in a medium. Also referred to as interstices. Size and shape of the openings are controlled by the manufacturer of the filter medium.

 

PORE SIZE
Diameter of pore in a filter medium.

 

PORE SIZE-ABSOLUTE RATING
The rated pore size of a filter. Particles equal or larger than the rated pore size are retained with 100% efficiency.

 

PORE SIZE-NOMINAL RATING
The pore size at which a particle of defined size will be retained with efficiency below 100% (typically 90-98%). Rating methods vary widely between manufacturers.

 

PORE SIZE DISTRIBUTION
Exclusive to permeable medium: describes the number of pores in various groups of sizes in a way similar to that discussed under particle size distribution.

 

POROSITY
The percent of open areas per unit volume of a medium whether it be a filter cake or roll stock, such as a paper, membrane, woven textile or nonwoven fabric.

 

POROUS METAL
Finely ground chards of sintered metal, which serve as a filter medium. Often used in high-pressure and/or temperature applications.

 

POROUS PLASTIC
Filter media made from finely ground plastic powder. When filled into a mold and heated, the points of powder contact to fuse, while allowing the spaces between the particles to remain open for fluid flow.

 

POTABLE
Drinkable (water).

 

PPM
Parts per million. A unit of concentration.

 

PRECOAT
A deposit of material (usually inert), such as a filter aid on a septum prior to beginning filtration.

 

PREFILT
Material to be filtered. Also referred to as concentrate, feed, influent, intake, liquor, mud, pulp slime or sludge.

 

PREFILTER
Filter for removing gross size contaminate before the product stream enters a finer rated filter.

 

PRESSURE, ABSOLUTE
Gauge pressure plus 14.7 psi.

 

PRESSURE, PROOF
A test pressure above normal operating pressure to assure that the part will withstand the norm without damage or leakage.

 

PRESSURE DIFFERENTIAL
Difference in pressure between two points.

 

PRESSURE DROP (ΔP)
Difference in pressure between two points.

 

PRESSURE DROP, CLEAN
Differential pressure (drop) across a housing measured in psi at rated flow on new elements with clean product.

 

PRETREATMENT
Changing the properties of a liquid-solid mixture by physical or chemical means to improve its filterability.

 

PRIMARY SLUDGE
That portion of the raw wastewater solids contained in the raw plant influent, which is directly captured and removed in the primary sedimentation process.

 

PRODUCT
Continuous phase, either liquid or gas, which is being process through filtration or separation equipment.

 

PROTEIN BINDING
Adsorption of a protein to a surface such as a cellulose nitrate or nylon membrane due to various types of interactions between protein molecules and the surface.

 

PSEUDOMONAS DIMINUTA
Bacteria used in sterility testing. One of the smallest bacteria, 0.3μm in diameter, used to challenge a sterilizing grade filter during validation testing.

 

PSI
Pounds per square inch.

 

PSIA
Pounds per square inch absolute.

 

PSID
Pounds per square inch differential.

 

PSIG
Pounds per square inch Gauge.

 

PULSING BACKFLOW
Intermittent, on-off blowing with or without cake discharge.

 

PTFE
Highly durable and resistant to range of temperatures and chemicals. PTFE is hydrophobic. Polytetrafluoroethylene is better known as Teflon.

 

PULSE-JET BAGHOUSE
A baghouse using short intermittent bursts of compressed air to clean dust/particulate from filter bags that are supported by cages.

 

PYROGEN
Any substance that produces a fever. Pyrogens are lipoplysaccharides which are a by-product of the metabolism of certain bacteria.

 

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Q

 

QUISCENT
State of rest of a body. In entrainment separation, the body would be a liquid. Also used to describe a sump containing evacuated liquids or solids.

 

 

 

R

 

RATED FLOW

 

Normal operating flow rate at which a product is passed through a housing; flow rate which a housing and medium are designed to accommodate.

 

RAW SLUDGE
Untreated sewage sludge.

 

REAGENT
Solution or substance used in analytical testing purposes or procedures.

 

RECOVERY
Ability of a filter to recover bacteria (or other defined particles) from a solution.

 

REENTRAINMENT
Process of rendering particles airborne again after they have been once deposited from an air stream.

 

RED MUD
Filter cake in sodium aluminate filtration.

 

RETENTION
Ability of a filter to retain particles suspended in a gas or liquid. A percentage of particles originally present.

 

REGENRATED CELLULOSE
Those rayon's in which the cellulose raw material is changed physically, but not chemically. Viscose, cuprammonium and nitrocellulose rayon's are of this type.

 

REPACK
Cylindrical element used in a single-stage filter separator for removal of one liquid and course solids from another liquid. May be used as a single element, a combination of wafers, or a cluster type. Medium may be excelsior, glass fiber or steel wool; or a combination of glass fibers and metal mesh.

 

RESIDUE
Solids deposited upon the filter medium during filtration in sufficient thickness to be removed in sizeable pieces. Sometimes referred to as a cake or discharge solids.

 

RESIDUAL DIRT CAPACITY
The dirt capacity remaining in a service loaded filter element after use, but before cleaning, measured under the same conditions as the dirt capacity of a new filter element.

 

RETENTION
Ability of a filter medium to retain particles of a given size.

 

REUSABLE FILTERS
Filters that are washed or cleaned of contaminate, either in-situ or off-line, for additional uses.

 

REVERSE OSMOSIS (RO)
A water treatment method whereby water is forced through a semi-permeable membrane which filters out impurities, such as salt (NaCl) from seawater.

 

REYNOLDS NUMBER
Any of several dimensionless quantities, of form LVp/N in theory of fluid motion.

 

ROTARY DRUM
Continuous liquid filter equipment consisting of a large rotating drum covered with a filter cloth and cake, which collects incoming particulate from a contaminated bath or flow. A washing and/or discharge device (scrapper) ultimately cleans the contaminate from the cake as the drum rotates.

 

 

 

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S

 

SAND FILTER
Filter composed of layers of sand, graded in particle size, so that the courser particles face the unfiltered flow.

 

SAYBOLT SECONDS UNIVERSAL
Units of viscosity as measured by observing the time in seconds required for 60 ml. of a fluid to drain through a tubular orifice 0.483 inches long by 0.0695 inches in diameter at stated conditions of temperature and pressure.

 

SCAVENGER
A filter or element in the bottom of a filter that recovers the liquid heel that remains in a filter tank at the end of a cycle.

 

SCREEN
Often a flat filter from wire cloth mesh or monofilament fabric filter used to classify particles of a certain size to "to screen out particles". Can also cover an element for protection; also used as a basic material for a separator element of basket in a basket strainer.

 

SCREW BASE
Element base which is threaded to mount by screwing the cartridge onto the cartridge adaptor.

 

SCRIM
An open weave textile or nonwoven fabric used as a strengthening member incorporated within the matrix of a filtration medium to provide increased tensile or tear properties.

 

SCRUBBER
Any device in which a contaminant, solid or gaseous, is removed from a gas stream by impacting it with liquid droplets.

 

SEDIMENTATION
Action of settling of suspended solids.

 

SEEDING
The application of a relatively course dust, dry dust to an air filter bag before filtration startup to provide an initial filter cake for immediate high efficiency and to protect the bag from blinding.

 

SELF-CLEANING
Filtering device designed to clean itself by the use of a blowdown or backwash action.

 

SEPARATION
Action of separating solids or liquids from themselves (e.g. by size, viscosity, density, charge etc,) or liquids or gases from fluids.

 

SEPTUM
Any permeable material that physically supports the filter media, usually for filter aids.

 

SERIAL FILTRATION
Filtration through two or more filters of decreasing pore size, one after the other, to increase throughput, filtration efficiency, or to protect the final filter.

 

SERVICE LIFE
Length of time an element operates before reaching an unacceptable benchmark e.g. maximum allowable pressure drop.

 

SHAKER BAGHOUSE
A baghouse using flexible bags applying a cleaning action accomplished by shaking the bags from the top.

 

SHELL
Outer wall of a housing. Also referred to as the body of a housing.

 

SIEVE
A screen filter with straight-though capillary pores and identical dimension.

 

SHIFTING
A separation process which separates solid particles by size, through rapid movement of a screen medium, such as a vibrating action. Used in flour, wheat, abrasive, sugar and aggregate sizing.

 

SILICIAGEL
regenerated adsorbent, consisting of amorphous silica. Used as a drying agent or dehumidifying agent for gases, liquids or oils.

 

SILTING INDEX
Measurement of the tendency of a fluid to cause silting in close tolerance devices as a result of fine particles and gelatinous materials being suspended in the fluid; measured by a silting index apparatus.

 

SINGLE-PASS
This test system is designed to be representative of a typical filter circuit. Fresh contaminates are introduced in a slurry form into the test reservoir, mixed with the fluid and pumped through the test filter. The test is run in such a manner to produce one pass of all fluid and contaminate.

 

SINTERING
A process of heating materials (e.g. metal or ceramic) to elevated temperature causing mating surfaces to fuse as one.

 

SIZE DISTRIBUTION
Proportion of particles of each size (by mass, number or volume) in a powder or suspension.

 

SLIMES
Slurry of fine particles; materials to be filtered. Also referred to as concentrate, feed influent, intake, liquor, mud, prefilt, pulp or sludge.

 

SLUDGE
A thickened slurry. Municipal sewage is often dewatered to produce a concentrate for disposal. Also, residues and deposits occasionally formed by oils, after extended use.

 

SLURRY
Thin, watery suspension; a material to be filtered or dewatered.

 

SOLIDS
Mass or matter contained in a stream, considered an undesirable discontinuous phase and should be removed.

 

SOLUTE
Liquid which has passed through a filter. Also referred to as discharge liquor, effluent, filtrate, mother liquor or strong liquor.

 

SOLUTION
Single phase combination of liquid and non-liquid substances of two or more liquids.

 

SOP
A written document that explains how to complete a specific production-orient-ed task. Standard Operating Procedure.

 

SPARGING
Steam, compressed air, or gas is forced into a liquid through perforations or nozzles in a pipe as part of fermentation.

 

SPECIFIC GRAVITY
Ratio of weight of a volume of a substance to the weight of an equal volume of another substance typically compared to water with a specific gravity (Sp.G.) of 1.0.

 

SPECTROPHOTOMETER
Laboratory instrument which measures the wave length and intensity of a light emitted by most chemical agents. When a sample is atomized and burned, the presence of most elements may be determined by their spectra (wave length) emission down to the parts per million range.

 

SPIN-ON-FILTER
Cartridge filter in which the filter body and the filter element have been constructed and an integral disposable item. Filter change is rapid by spinning off the used unit from a fixed filter head and rapidly adding on the replacement unit.

 

SPUNBOND
A nonwoven fabric formed by producing, laying and self-bonding a web of filament material in one continuous set of processing steps. Usually made of polyester or polyolefin's.

 

SS
Abbreviation for stainless steel.

 

SPUN YARN
A continuous yarn for weaving of textiles consisting of staple fibers.

 

STACKED DISC FILTER
A filter housing and device consisting of a plurality of leaves place in a horizontal position. Used widely in food and beverage filtration.

 

STAPLE FIBER
A short length of natural or synthetic fiber typically from 1-4 inches in length, used to manufacture yarns for weaving and various types of nonwoven fabrics, such as needlefelt, airlaid and hydroentangled for use in filtration media.

 

STERILIZING FILTER
A non-fiber releasing filter which produces an effluent in which no microorganisms are present. Typically microporous membranes at or below 0.2 micron pore size rating have this capability.

 

STOKE'S DIAMETER
Diameter of a sphere having the same density and the same free falling speed as a particle when moving in a homogeneous fluid of the same density and viscosity, under conditions of laminar flow.

 

STOKE'S LAW
A physical law, which approximates the viscosity of a particle falling under the action of gravity through a fluid. Friction drag controls the rate of fall at a constant velocity known as the terminal or free-setting velocity.

 

STRATIFICATION
Condition in which the larger particles settle out below the finer ones. Also referred to as classification.

 

STREAM
Term sometimes used and synonymous with the words product, liquid, air, gas, fluid etc. in speaking of any matter processed by filtration or separation equipment.

 

STRING WOUND
An inexpensive filter consisting of textile roving (yarn) wrapped around a center core to form a filter medium and filter cartridge (element).

 

STRONG LIQUOR
Liquid which has passed though the filter. Also referred to as discharge liquid, effluent, filtrate, mother liquor or solute.

 

SUBSTRATE
Substance or basic material as a filter media or to which a deposit is added.

 

SULPA (Super ULPA)
An air filter or medium, which captures 99.9999% when challenged with DOP 0.3 micron particles under certain laboratory control conditions.

 

SUMP
Collecting area of a housing located downstream typically from a coalescer element, in which coalesced droplets of the dispersed phase are deposited; also called water leg. May also be used to collect solids in applications where gross solids are present in a stream; also called mud sump.

 

SUPERNATANT
Liquid above settled solids.

 

SURFACE ENERGY
Molecular reaction; the breaking away of ion particles from a mass.

 

SURFACE FILTER
Filter medium that retains particles wholly on the surface and not in the depth of the cross-section of a filter medium e.g. plain weave wire cloth and monofilament woven fabrics or membrane.

 

SURFACE FILTRATION
A process that traps contaminants larger than the pore size on the top surface of the filter, usually a membrane, wire cloth or monofilament fabric. Contaminants smaller than the specified pore size may pass through the medium or may be captured within the medium by some other mechanism, such as surface affinity, triboelectric potential or other means, which prevents particle penetration.

 

SURFACE TENSION
Tendency of the surface of a liquid to contract to the smallest area possible under existing circumstances.

 

SURFACTANT
A soluble compound that reduces the surface tension of a liquid, or reduces interfacial tension between two liquids or between a liquid and a solid.

 

SURGE
Peak system pressure measured as a function of restricting or blocking fluid flow.

 

SUSPENDED SOLIDS
Solids that do not dissolve in liquid; those that remain suspended and can be removed by filtration.

 

SUSPENSION
Any liquid containing un-dissolved solids.

 

SWING BOLT
Type of housing head closure which reduces service time. Opposite of thru-blot flange where studs are used, such as with ASA type flanges.

 

 

 

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T

 

TANGENTIAL (CROSSFLOW) FILTRATION
See Crossflow (Tangential) Filtration.

 

TARE
A deduction of weight, allowing for the weight of a container or medium; the initial weight of a filter.

 

TENSILE STRENGTH
Resistance to breaking. The amount of force required to break a membrane by stretching.

 

TENSIOMETER
Device used to read the surface tension of a liquid or to reading the interfacial tension between two immiscible liquids.

 

TERMINAL PRESSURE
Pressure drop across the unit at the time system is shut down or when the maximum allowable pressure drop is reached.

 

TERMINAL VELOCITY
3Steady velocity achieved by a falling particle when gravitational forces are balanced by viscous forces.

 

THREE-STAGE FILTER SEPARATORS:
Liquid prefilter coalescer separators containing three kinds or types of replaceable elements.

 

THROUGHPUT
The amount of solution which will pass through a filter prior to plugging.

 

TIPPING PAN FILTER
Process
industry equipment which collects particulate from a liquid stream on a screen over a vacuum forming a dewatered cake and discharging the accumulation by tipping the collection screens.

 

TORTUOUS PATH
Crooked, twisting or winding path which tends to trap or stop solid particles, commonly referenced in relationship to the flow pattern and makeup of a filter medium.

 

TRAMP OIL
Free oil contained in emulsion type machine tool coolants. May be from machine leakage and from breakdown of the emulsifying agents in the cutting oil.

 

TRIBOELECTRIC SERIES (POTENTIAL/CHARGE)
An inherent natural or induced positive or negative polarity charge that many materials possess. Fibers or a filtration medium with a triboelectric potential will capture charged and potentially neutral particles, assuming both positive and negative properties on the surface of the material. Triboelectric properties only work in air filtration assuming relative humidity below 90 %.

 

TRIBOELECTRICITY
The charge of electricity that is generated by friction such as rubbing.

 

THROUGHPUT
The amount of solution which will pass through a filter before clogging.

 

TOTAL DISSOLVED SOLIDS
Is the portion of the total solids in the sample that passes through the filter and is indicated by the increase in weight in the vessel after the filtrate has been dried at 356ºF.

 

TOTAL SOLIDS / SUSPENDED SOLIDS
The material residue left in the vessel after evaporation of a sample and its drying in an oven at 217-221ºF. The increase in weight over that of the empty vessel represents the total solids. Used in analyzing drinking water.

 

TORTUOUSITY
An continuous path that can be traced from a point on the upstream side of a filter to a point on the downstream side through a twisting pore pathway, traveled by the liquid or gas during filtration.

 

TRUE DENSITY
Mass of a particle divided by its volume, pores etc. being excluded from the volume calculation.

 

TURBIDIMETER
An instrument for measurement of turbidity, in which a standard suspension usually is used for reference.

 

TURBIDITY
Any insoluble particle that imparts opacity to a liquid. A reference point to the total amount of solids contained in a liquid.

 

TRUBULANT FLOW
Flow regime in which the flow characteristics are governed mainly by the inertia of the fluid. Turbulent flow in ducts is associated with high Reynolds Number (Re). It also gives rise to high drag.
verned mainly by the inertia of the fluid. Turbulent flow in ducts is associated with high Reynolds Number (Re). It also gives rise to high drag.

 

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U

 

U.S.P.
United States Pharmacopeia/National Formulary: The "Bible" of pharmaceutical manufacturer and test protocol for filtration media using Edition/Title XXI as a basis for evaluation.

 

ULPA
An air filter or medium, which captures 99.999% when challenged with DOP 0.3 micron particles under certain laboratory controlled conditions.

 

ULTRAFILTRATION (UF)
A separation method operating at 50-200 psi in crossflow filtration mode. Efficiency is approximately 90%. Used to separate large molecules according to their molecular weight.

 

UNIFORMITY COEFFICIENT
Separation factor applied to the sizing of the sand used in water filtration plants.

 

UNIFORMITY OF FEED
Uniformity of the mixture of the solids in the feed liquid.

 

UNLOADING
The release of contaminate downstream that was initially captured by the filter medium.

 

UPSTREAM SIDE
The feed side of the filter. Fluid that has not yet entered the filter.

 

USEFUL LIFE
Determined when contamination causes a filter or system to have an adverse (lower) flow rate, low efficiency or high differential pressure, providing for an inefficient operation.

 

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V

 

VACUUM
Depression of pressure below atmospheric pressure.

 

VALIDATION
Demonstration that a process or product does what it is supposed to do by challenging the system and providing complete documentation.

 

VAN DER WALS FORCES
The relatively weak attractive forces that are operative between neutral atoms and molecules that arise because of the electric polarization induced in each of the particles by the presence of other particles.

 

VELOCITY
Time rate of motion in a given direction.

 

VELOCITY HEAD
Velocity pressure or kinetic pressure.

 

VENT FILTERS
Filters that allow the passage of air while restricting the flow of fluid; typically containing low micron rated microporous membrane media. Common in medical devices and pharmaceutical tanks.

 

VESSEL
A container, usually used as alternatively to the word housing e.g. filter vessel.

 

VIBRATORY SIFTER: Process equipment that separates solids by size on a metal screen through a vibrating action. Larger particles remain on the screen as fines fall through, sometimes to one or more higher mesh count screens for further separation of particle size.

 

VISCOSITY
Degree of fluidity. Resistance to flow as a function of force, or gradual yielding of force. For a given filter and differential pressure, flow rate will decrease as viscosity increases.

 

VISCOSITY INDEX
Numerical value assigned to a fluid which indicates to what degree the fluid changes in viscosity with change in temperature.

 

VOID VOLUME
The amount of open or empty area across the full spectrum of a material or substance. A term often used to describe the amount of porosity in a filter medium.

 

VOLUMETRIC FLOW RATE
Fluid flow expressed as a volume flowing per unit of time (cc.3/sec., ft3/min., etc.)

 

 

 

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W

 

WARP
The yarns that run lengthwise or in the machine direction in woven goods.

 

WASTE
Material removed, rejected or otherwise lost in various manufacturing processes.

 

WASTEWATER
Effluent water carried downstream from a filtration or separation process.

 

WATER BREAKTHROUGH TEST (WBT)
An integrity test for hydrophobic filters or filter medium in which the resistance to water flow is overcome by a specific pressure such that water will flow through a specific pore size of the filter or filter medium. Also called Water Intrusion Test.

 

WATER FLOW/FLUX
Measure of the amount of water that flows through a filter, a variable of time, the degree of contamination, differential pressure, total porosity and filter area.

 

WATERHEAD
The height of water in a column. Provides a defined amount of pressure on a surface.

 

WATER INTRUSION TEST
See Water Breakthrough Test above.

 

WATER LEG
Area of housing for collection of water.

 

WEIGHT OF SOLIDS
Measure of solid particulate matter contained in a fluid sample.

 

WEIR
(1) A diversion dam (2) A device that has a crest and some side containment of know geometric shape, such as a V, trapezoid or rectangle and is used to measure flow of a liquid.

 

WET CAST MEMBRANE
A process to manufacture microporous membranes, typically from thermoplastic materials, solvents and non-solvents in the formation of a microporous membrane. 75 to 80% of all microporous membranes manufactured use this process.

 

WET STRENGTH
Strength of a medium when saturated with water.

 

WETTING AGENT
A surfactant added to a filter medium to insure complete intrusion (wetting) by a high surface tension fluid such as water.

 

WIRE CLOTH
Woven fabric from metal wire used as a screen, surface filter or media support. Often used in sifting, belting, hydraulic filtration etc. Most common wire used is stainless steel.

 

WOUND TUBES
Also referred to as string wound filters.

 

 

 

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Y

 

YOKE
End cap used to hold a cartridge in place.

 

 

 

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Z

 

Zeta Potential
The potential across the diffuse layer of ions surrounding a charged colloidal particle.

 

 

 

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Source:
The American Filtration & Separations Society

 

 

 

 

 

 

ISO 14644-1  & FED STD 209E - Cleanroom Standards

GVS manufacture  range of minipleat HEPA filters and ceiling modules to suit most cleanroom applications. 
Cleanrooms are classified according to the number and size of particles present in a fixed volume of air.

Class	Maximum Particles/m3						FED STD 209E
	≥0.1 µm	≥0.2 µm	≥0.3 µm	≥0.5 µm	≥1 µm	≥5 µm	equivalent
ISO 1	10	2,37	1,02	0,35	0,083	0,0029
ISO 2	100	23,7	10,2	3,5	0,83	0,029
ISO 3	1.000	237	102	35	8,3	0,29	Class 1
ISO 4	10.000	2.370	1.020	352	83	2,9	Class 10
ISO 5	100.000	23.700	10.200	3.520	832	29	Class 100
ISO 6	1.0×106	237.000	102.000	35.200	8.320	293	Class 1,000
ISO 7	1.0×107	2.37×106	1.020.000	352.000	83.200	2.930	Class 10,000
ISO 8	1.0×108	2.37×107	1.02×107	3.520.000	832.000	29.300	Class100,000
ISO 9	1.0×109	2.37×108	1.02×108	35.200.000	8.320.000	293.000	Room air

 Note: US FED STD 209E was officially cancelled by the General Services Administration on November 29, 2001 but is still commonly used.

ISO13485:2016 - Medical Devices Quality Management

ISO13485 is a quality management system for medical device manufacturers. It works alongside IS9001 to define a best practice for the manufacture of medical devices. Some of the key points within ISO13485 are:

• The standard promotes regulatory requirements as a management responsibility.
• Controls within the workplace are in place to ensure product quality.
• There is a requirement for verification of the effectiveness of corrective and preventive actions.
• There is a focus on risk management and design control processes during product development.
• The standard ensures inspection and traceability for implantable devices
• The standard asks for documentation and validation of processes for sterile medical devices.

All the GVS facilities globally that produce medical devices have both ISO9001 and ISO13485 in place to ensure the maximum level of product quality is maintained.

EN1822:2009 - EPA, HEPA and ULPA Filters

The table below shows the classifications, descriptions and efficiencies of filters covered by the EN1822:2009 standard:

		Integral Value		Local Value
Filter Class	Description	Collection Efficiency (%)	Penetration (%)	Collection Efficiency (%)	Penetration (%)
E10	Efficiency Particulate Air Filters	85	15	-	-
E11		95	5	-	-
E12		99,5	0,5	-	-
H13	High Efficiency Particulate Air Filters	99,95	0,05	99,75	0,25
H14		99,995	0,005	99,975	0,025
U15	Ultra Low Penetration Air Filters	99,9995	0,0005	99,9975	0,0025
U16		99,99995	0,00005	99,99975	0,00025
U17		99,999995	0,000005	99,9999	0,0001

 

Testing
EN 1822 testing is conducted with an aerosol test probe that is moved over the entire surface of the filter in a scanning motion. This scanning, results in the local measurement of the whole surface of the filter. These local efficiencies can be used to calculate the overall efficiency of the filter or the leak rate of a specific area of the filter. The overall efficiency calculation is termed the integral value the area immediately around the probe is the local value.

Tests are performed on new filters at the specified nominal volumetric air flow. Filters of U15 or above are scanned with a particle counter probe. An oil thread test can be utilized on filters of H13 and H14 classification.

GVS manufacture a wide range of HEPA filters which comply to the EN1822:2009 standard. Our Minipleat HEPA range of filters are individually tested using our DOP test rig with scanning probe and each is individually labelled and certified.

16890 Standard

Over the past five years, a new approach has been developed to characterize filter efficiency. The new standard now aligns more closely with the way air quality is measured.   

This new approach is to look at filtration efficiency not only for particles with a diameter of 0.4 μm but to consider the entire spectrum of particle sizes.   

The current EN779: 2012 standard used today in Europe defines the filtration classes according to the average filtration efficiency of the particles with a diameter of 0.4 μm.  

The convention of using only the filtration efficiency of particles with a diameter of 0.4 μm is due to the fact that particles of this size are the most difficult to filter. For particles with a smaller diameter, the phenomenon of diffusion predominates, whereas for particles with a larger diameter, the phenomenon of interception is predominant. (see GVS Filtration guide for more details).   

For most HVAC media filtering the minimum efficiency is around 0.4 μm.   

The current system therefore makes it possible to compare different filters but it is not easy to evaluate the effectiveness of a filter with regards to its impact on air quality.   

The new standard characterises the filters in the same way as we measure air quality: Particulate Matter (PM)concentrations: PM10, PM2.5 and PM1 which respectively define the air concentrations in liquid or solid particles whose diameter is below 10, 2.5 and 1 µm.  

These indicators are used in many health and toxicological studies. They make it possible to classify the particles according to their effect on the human body.   

• Particles with a diameter greater than 10 μm are retained by the upper airway.
• Particles with a diameter of less than 10 μm (PM10) can penetrate the bronchi.
• Particles with a diameter below 2.5 μm (PM2.5) can penetrate the pulmonary alveoli.
• Particles with a diameter below 1 μm (PM1) can penetrate the alveoli-capillary barrier.  

 

The new standard therefore classifies filters relative to their filtration efficiency for these different particle sizes according to the table below.  

 

Table 2. Filter classification according to ISO 16890-1. 

 

Group	Initial efficiency in PMx	Discharged efficiency PMx
ePM10	≥ 50% (PM10)	≥ 50% (PM10)
ePM2.5	≥ 50% (PM2.5)	≥ 50% (PM2.5)
ePM1	≥ 50% (PM1)	≥ 50% (PM1)

At PM1 the efficiency of a filter classified as ePM1[80%] will be above 80% and below 85%. 

Beyond the new approach of classification of the filters certain improvements over the old standard have been added: 

Requirements have been introduced with for test conditions in terms of temperature and relative humidity.

• The conditioning method for determining the minimum efficiency makes it possible to test a complete filter and not only the filter media as with the EN 779: 2012.
• "Fine AC" dust is used to determine gravimetric efficiency as a replacement for standardized dust such as “ASHRAE”.

EN13779 - IAQ - Indoor Air Quality

Tenants and occupants of commercial buildings are increasingly bringing IAQ legal cases against defendants associated with building construction and maintenance. The EN13779 Standard for indoor air quality deals with both the comfort and health of people using buildings and well as the cost of installing and running HVAC systems. It is now an international standard. The standard starts by classifying outdoor air quality. This is classified from ODA1 to ODA3 where ODA1 is pure air with only low levels of naturally occuring pollution up to ODA3 with high levels of both gaseous and particulate contamination.

Previously there was a focus on PM10 particulate, often from vehicle exhaust fumes, and originally thought to be a major source of respiratory illness. More recently it has been found that the smaller particulate and gases can also cause serious health issues. There is now a focus on PM10 as well as PM2.5, CO, CO2, NOX, SO2 and VOCs.

The table below indicates typical concentration levels in outdoor air, together with a suggestion on how to categorize the quality.

Outdoor Air Quality

Description of Air quality	Concentration Levels					Outdoor Air Catagory
	CO2 (ppm)	CO2 (mg/m2)	NO2 (μg/m2)	SO2 (μg/m2)	PM10 (μg/m2)
Rural areas with no significant sources	350	< 1	3 - 35	< 5	< 20	ODA1
Smaller towns	400	1 - 3	15 - 40	5 - 15	10 - 30	ODA2
City centres	450	2 - 6	30 - 80	10 - 50	20 - 50	ODA3

Looking at the above chart and comparing the figures to air quality test results conducted in most major cities it is interesting to note that the often fall into the ODA3 or are well above the limits. As outdoor air at street level is concentrated through the effect known as canyoning and blown over building roof tops it is then pulled into buildings via the HVAC system. This often means indoor air quality can be worse than the air outside.

The table below looks purely at CO2. Obviously this is only one of the many contaminants that need to be dealt with. The table doesn't cover particulate or other gaseous contaminants.

Classification of Indoor Air Quality

Category	Description	CO2 –level above level of outdoor air (ppm) Typical range		Air changes in
				(m3/h/person)
				(Non-smoking areas)
IDA 1	High IAQ	< 400		>54
IDA 2	Medium IAQ	400 – 600		36 - 54
IDA 3	Moderate IAQ	600- 1000		22 – 36
IDA 4	Low IAQ	> 1000		< 22

 

GVS Filter Recommendations Based on Indoor and Outdoor Air Quality

Outdoor Air Quality	IAQ (Indoor Air Quality)
	IDA 1 (High)	IDA 2 (Medium)	IDA 3 (Moderate)	IDA 4 (Low)
ODA1	F9	F8	F7	M5
ODA2	F7 /  F9	M6 / F8	M5 / F7	M5 /  M6
ODA3	F7 / CF / F9	F7 / CF / F9	M5 / F7	M5 / M6

CF - Carbon Filter (GVS Bacticell Enviro-carb may be used to replace both the F7 and the CF)

General Filration Best Practice

Replace filters as follows:	Primary Filters		2000hrs
	Secondary Filters		3000hr or 2 years - whichever comes first
	Exhaust and recirc.		3000hr or 2 years - whichever comes first
	Gas filters		5000hrs
To avoid microbial growth keep RH levels below 85% and fit filters with biocidal impregnation such as Bacticell with Bacti-G.
In city centres or areas with ODA3 air fit a molecular gas filter such as the GVS Enviro-carb.

ISO/TS 16949 Automotive Quality Management

ISO/TS16949 is an ISO technical specification for the development of a quality management system for continual improvement, emphasising defect prevention and the reduction of variation and waste in the supply chain. It is based on the ISO 9001 standard and the first edition was published in June 1999 as ISO/TS 16949:1999.  It harmonizes the a number of different local country quality Management systems.
TS16949 applies to the design/development, production and, when relevant, installation and servicing of automotive-related products.
The requirements are intended to be applied throughout the supply chain.
GVS obtained TS16949 in 2005 and follows the standard in the automotive production areas in Europe, Brazil, China and the USA.

 

The Theory of Filtration

Particulate matter is captured within a filter by 4 main methods:

	Straining The physical capture of a particle by the fibres or holes in a media preventing it passing due to their relative size.
	Impingement The particle physically hits and sticks to the fibre.
	Diffusion Brownian motion causes the particle to move in irregular patterns increasing it chance of making contact with and adhering to the filter fibres.
	Electrostatic The particulate is attracted to the media though an electrostatic charge. This is generally only in synthetic media and very often this electrostatic charge diminishes with time and/or humidity.
	MPPS The most penetrating particle size varies between different media, contaminants and according to air flow. Generally as air flow increases, efficiency decreases.

 

 

UK Test Lab

Woven Mesh Characteristics

Raw materials GVS open mesh fabrics offer you the greatest design flexibility. Raw materials used for the monofilament are polyamide (PA6.6), polyester (PET) and polypropylene (PP) in particular, but other materials for highperformance filter materials (PEEK) and fluorinated polymers (ETFE) or metals (Al, Cu, Ag, Au, Cu-Al, Ti and Ni) are also available upon request. Mesh opening This is the size (micron) of any window or opening. The openings are tested by electronic analysis image systems during production. Open area This is a percentage (%) of the total mesh area which is “open” to let the flow go through. It’s important to have high open area percentage to reduce flow restriction. This is also tested by electronic analysis image systems during production. Mesh count This is the quantity of threads per cm (n/cm) or per inch (n/in). Thread diameter This is the diameter (micron) of the filament. It is also tested by electronic analysis image systems during production. Weight of the mesh It is important to qualify the quality of the mesh, (g/m2) or (oz/yd2) Thickness of the mesh Thickness is expressed in microns (μm) and its stability is very important to achieve the proper handling of the mesh during production. Effective Filtration Area (EFA) This is the actual filtration area in a device that is subject to filtration. For instance, in a tubular filter, the frame (socket, two ribs and top cover) made by plastics should be eliminated from the calculations of the device EFA. In mesh filters you should only eliminate the seal area. Micron Retention The diameter of the largest round particles which can pass through a filter. Since absolute Micron Retention can change during filtration, aperture size can be determined by Bubble Point and Glass Bead Tests methods. Bubble Point Test The pressure required to force air bubbles through a wetted mesh. These tests are typically performed with water; however, test can be conducted on mesh using test liquids other than water. The BP is an indication of the pore size. The average size can then be calculated by taking into account surface tension, liquid density, temperature and immersion depth. Glass Bead Test A mixture containing glass beads is passed through the mesh, the diameter of the largest bead passing through is considered as the absolute micron retention. Filter Efficiency (FE) This is the quantity of particulate retained compared to the total quantity of particulate to which the filter is challenged. It is expressed in % and refers to a specific size of particles. The filter efficiency is determined by a pass test which allows the measurement of the percentage of particles which are removed by the filter. It is expressed by a beta rating representing the effectiveness of the filter that can be calculated as follows:

 

Total Filter Life Cost

Selecting filters suitable for an application should always be done considering operating costs. Generally a filter costs more to use than it does to buy. Replacing existing filters such as traditional panel and bag filter with the same may seem the most cost effective option at the time but may cost more in the long run though increased elecrical consumption.
Replacing with a cartridge filter with large media area, sometimes without a pre-filter in place, very often reduces resistance and increases time between changes.
Make filter specification decisions by weighing up the operating costs, filter changeout costs, waste disposal costs as well as the filter cost.
The below graph demonstrates the the thoery and for this optimum change-out schedule:

 

 

 

Eurovent 4/11 Air Filter Energy Efficiency Ratings

 

The 4/11 standard is a very useful energy saving guideline introduced in 2012. However it only test to 100g dustload and does not represent the additional use of a pre filter. The Bacticell filter does not always require a pre filter and can hold up to a 512g dustload. By extending the Eurovent 4/11 testing we can show the long term filter sustainability by testing at 100g, 200g and 400g dustloadings, both with and without a pre filter.

 

Filter Combination	100g	200g	400g
F7 Bag filter 592x592x600mm 8 pockets	A	C	X
G4 Pleat and same F7 Bag Filter	D	G	X
F8 Bacticell 592x592x292mm	A	A	C
G4 Pleat & same F8 Bacticell	B	D	G

 

GVS Filter Technology is a member of FETA/HEVAC and forms part of the UK Air Filter Group. As a member of the Eurovent Certification Scheme for fine grade air filters product quality from GVS Filter Technology is assured with the requirement for testing to be conducted by authorised independent laboratories on an annual basis. In addition, products are also tested under the more stringent LSS/J/Edition III.1990. test procedure to assess the entire filter for flammability and toxic smoke emission as well as BS5588 Part 9 in respect of flammability. On-site testing programmes are also commissioned from independent research establishments to verify laboratory test results.

 

 

 

 

HVAC - Air changes per hour

Air changes per hour, or air change rate, abbreviated ACH or ac/h, is a measure of the air volume added to or removed from a space (normally a room or house) divided by the volume of the space.[1] If the air in the space is either uniform or perfectly mixed, air changes per hour is a measure of how many times the air within a defined space is replaced.
In many air distribution arrangements, air is neither uniform or perfectly mixed. The actual percentage of an enclosure's air which is exchanged in a period depends on the airflow efficiency of the enclosure and the methods used to ventilate it. The actual amount of air changed in a well mixed ventilation scenario will be 63.2% after 1 hour and 1 ACH.[2] In order to achieve equilibrium pressure, the amount of air leaving the space and entering the space must be the same.

Where:
N = number of air changes per hour
Q = Volumetric flow rate of air in cubic feet per minute (cfm)
Vol = Space volume L × W × H, in cubic feet

Ventilation rates are often expressed as a volume rate per person (CFM per person, L/s per person). The conversion between air changes per hour and ventilation rate per person is as follows:

Where:
Rp = ventilation rate per person (CFM per person, L/s per person)
ACPH = Air changes per hour
D = Occupant density (occupants per square foot, occupants per square meter)
h = Ceiling height (ft, meters)

 

Reference - Wikipedia

Bacti-G - How it works

Introduction
You have all seen a used air filter, caked with insects, plant debris, soil dust, traffic pollution staining etc. Given the dark, humid location where an air filter is used, common sense backs up numerous tests to assure us that bacteria and other micro-organisms can colonise within the filter). 

It's these filters that your fresh air will be drawn for the next 3-12 months. There are numerous "anti-microbials" offered in air filtration, however GVS concentrate on killing micro-organisms within the debris caught within the filter.

The patented GVS Bacti-G compound is impregnated into filter media and eradicates micro-organisms on contact. This prevents the gradual migration of organisms from the surface of the media (or ‘cake’ of build-up contaminant) through to the clean air side.

 

Bacti-G is not water based and does not dry out. Its patented formulation stays permanently ‘wet’ allowing it to remain effective throughout the normal operating life of the product. (Normally 18-24 months in a warm ar stream).

Biocidal compositions may be divided into two families: inhibitors and eradicators. The former work on the basis of encasing the micro-organism and causing it to adhere to a surface and thereby be prevented from moving, or holding it in the solution so that it may be washed or wiped away. While the micro-organism may eventually die under these circumstances, the biocide serves only to contribute towards the death of the micro-organism. Eradicators, while they may also display similar properties to inhibitors, are so deemed because the active element of the biocide succeeds in penetrating the cell wall of the micro-organism and killing it directly.
Bacti-G eradicates micro-organisms by acting as a ‘wetting agent’ to affect the surface tension of the cell wall (a physical reaction) which in turn enables the active agents to enter into the cell via osmosis to bring about eradication. 

Note: The ISO846 test standard is often applied to Biocides. This standard is not appicable to biocidal compounds impregnated into media as used on some GVS products as it refers to Biocides used on plastics. The standard is useful therefore only for products made from plastic such as filter frames.

 

Functions
A wide range of compounds are known to be effective eradicators. However, for them to be successfully incorporated into a supporting matrix (i.e. a substrate) and able to work on an ongoing basis the composition needs to perform a number of functions.
First, it must act as a wetting agent and have a physical effect on the surface of the micro-organism and affect adsorption and/or the surface tension. In the case of the former this would cause the micro-organism to be ‘captured’ by the compound and washed/wiped away. An effect on the surface tension may have a similar result, but can also aid the penetration of the cell wall by an anti-bacterial agent.
In order to affect adsorption or surface tension the molecule of the agent must contain a polar or hydrophilic (soluble in water) portion combined with an oily or lipophilic (soluble in lipids) portion. There are four main groups of compounds that may perform in this way: anionic, cationic, nonionic and ampholytic. They each perform in a slightly different way. For instance cationic compounds are strong electrolytes, while nonionic agents rely on structural features other than ions to affect hydrophilicity. Meanwhile, anionic and cationic agents cannot be mixed, but those in the ampholytic group may be either anionic or cationic. The selection of compounds to be used will depend on a number of factors according to the intended circumstances of use and/or the substrate into which the composition may be incorporated.
Second, the composition should be equally effective against both gram positive and gram negative bacteria to avoid the need to use more than one anti-microbial composition. Research indicates that cationic agents are effective against both.
Third, the composition needs to be able to retain its apparent liquidity in order to continue to affect adsorption or the surface tension of the micro-organism. If the composition were to ‘dry out’ this would cease to happen and it would not be possible to create the circumstances by which the micro-organism could either be washed/wiped away, held in position, or penetrated on an ongoing basis. Further applications would be needed to maintain the anti-microbial activity.
Finally, the composition must remain stable, with none of the agents acting to negate the properties of the other. This must also apply when the composition is combined with a substrate.

Conclusion
Research by GVS and independent labs has found that cationic surfactants are the most effective against both gram positive and gram negative bacteria, and in this category quaternary ammonium compounds are more effective. The anti-microbial activity is further enhanced with the addition of a nitrogen-containing agent. The ability to maintain the apparent liquidity of the composition is achieved by the addition of a glycol which also serves as a carrier for the anti-microbial agents.

 

 

ASHRAE vs. EN779 - US ASHRAE & European EN Test Standards

 

Air filters generally rely on two ‘main’ principles for capturing particulate contamination: one being ‘mechanical’ and the other ‘electrostatic’. Mechanical filtration basically relies on a ‘barrier’ of fibres interwoven to form a matrix through which the air has to pass, the closer or ‘tighter’ the matrix, the higher the filter efficiency. The electrostatic principle is employed to ‘charge’ material fibres (often with a more open matrix) during production in order to enhance filter efficiency. It has been established beyond doubt that certain types of ‘challenge’ such as combustion particles in normal atmospheric air may neutralise such charges resulting in serious loss of filter efficiency. This has led to three fundamental changes within the 2012 standard (differing from the 2002 version):

 

1. Compulsory discharge of all media: High efficiency filters of F7 - F9 are subject to a ‘discharge process’ to remove any electrostatic charge inorder to establish an initial ‘untreated efficiency’.
2. Minimum Efficiency value introduced: Filter grades F7 - F9 were previously determined by an average efficiency. The new standard requires that in addition to this, minimum efficiency values must also be met. The minimum efficiency value is defined as: ‘the lowest efficiency among the discharged efficiency, initial (clean filter) efficiency and that established throughout the full dust loading test. The minimum efficiency values required to be met are detailed in the table below.
3. Medium Grade classification introduced: Filter grades previously defined as ‘fine grade filters’ F5 & F6 are now classified purely as ‘medium.

 

Eurovent 4/11 is a guideline that defines a method of air filter classification with regard to energy-efficient operation. The method allows for an energy rating classification of filter grades G4, M5 & M6 and F7 to F9, and is based on the testing of air filters against EN 779: 2012, with a calculation that encompasses three set and one variable criterion. (see below)

 

Set criteria: A rated air volume (0.944 M3/s), a filter operation time based on 12 months (6000 hours) and a fan efficiency of 50%.

 

Variable value: an average operating pressure loss, determined by establishing a ‘nominated final’ filter pressure loss at a given test dust holding capacity (this varies for different grades and is detailed as MG, MM and MF in the table below). The average pressure loss is the mean between the initial (clean filter) pressure loss and the ‘nominated final’ pressure loss. The calculation used is:

 

 

ASHRAE 52.2				ASHRAE 52.1
	Particle Size Range			Test		Particle size range, μm	Applications
MERV	3 to 10μm	1 to 3μm	0.3 to 1μm	Arrestance	Dust Spot
1	<20%	-	-	<65%	<20%	>10	Residential, light pollen, dust mites.
2	<20%	-	-	<65-70%	<20%
3	<20%	-	-	70-75%	<20%
4	<20%	-	-	>75%	<20%
5	20-35%	-	-	80-85%	<20%	3.0-10	Industrial, dust, mold, spores.
6	35-50%	-	-	>90%	<20%
7	50-70%	-	-	>90%	20-25%
8	>70%	-	-	>95%	25-30%
9	>85%	<50%	-	>95%	40-45%	1.0-3.0	Industrial, legionella, dust.
10	>85%	50-65%	-	>95%	50-55%
11	>85%	65-80%	-	>98%	60-65%
12	>90%	>80%	-	>98%	70-75%
13	>90%	>90%	<75%	>98%	80-90%	0.3-1.0	Hospitals, smoke removal, bacteria.
14	>90%	>90%	75-85%	>98%	90-95%
15	>90%	>90%	85-95%	>98%	~95%
16	>90%	>95%	>95%	>98%	>95%
17	-	-	>99.97%			<0.3	Cleanrooms, surgery, chemi-bio, viruses.
18	-	-	>99.99
19	-	-	>99.999%
20	-	-	>99.9999%

 

 

 

EN779:2012		EN1822:2009
Class	Average 0.4μm	Class	MPPS Efficiency, %
G1	-	-	-
G2	-	-	-
G2	-	-	-
G2	-	-	-
G3	-	-	-
G3	-	-	-
G4	-	-	-
G4	-	-	-
G4	-	-	-
M5	40~60%	-	-
M6	60~80%	-	-
M6	60~80%	-	-
F7	80~90%	-	-
F8	90~95%	-	-
F9	>95%	-	-
-	-	E10	85%
-	-	H13	99,95%
-	-	H13	99,95%
-	-	H14	100,00%
-	-	H14	100,00%

 

 

 

Note: European and American test methodologies vary and therefore it is not possible to make direct comparisons between the standards. The above table is provided as a guide only.
Acknowledgements: (Paolo Tronville and Richard D. Rivers 2005)

 

 

Applying EN 779: 2012 in conjunction with Eurovent 4/11 (Energy classification)

 

Due to the requirement for F7 to F9 filter grades to meet minimum efficiency requirements, certain filter types previously available should have been re-classified.

 

Bag filters manufactured from synthetic materials are most likely to need reclassification as the majority rely on electrostatic properties to enhance performance/efficiency. Independent tests conducted on many of these products indicate minimum efficiency levels (after discharge) to be well under 30% for previously graded F7 and F8 classes. (Minimum efficiencies now required to be met are: 35% for F7, 55% for F8 and 70% for F9).

 

Products relying mainly on ‘mechanical properties’ to achieve filter efficiency requirements (such as glass bag filters and cartridges manufactured from filter paper materials) are less likely to require re-classification as these typically achieve minimum efficiency levels (after discharge) in the order of: >50% for F7 and >70% for F8.

 

In addition to meeting the above requirements, air filter manufacturers and suppliers must now support product claims with independent testing by a laboratory authorised to test products against EN 779: 2012. Without such tests being conducted, an ‘energy rating classification’ to Eurovent 4/11 cannot be applied.

 

 

 

 

 

 

 

 

Theory and Standards

Selecting filters suitable for an application can be difficult without an understanding of the principles behind the operation of the product. Many applications also have specific standards that must be followed. On the left are links to the GVS filtration guidance pages that provide some background information and also brief guidance to a selection of common standards.

LINKS

 

 

 

General Information

EDANA - European Disposables and Nonwovens Association

The Membrane Industry Association of China

European Membrane Society

EDS - European Desalination Society Secretariat

The Association of Liquid Filtration and Purification Industry (LFPI)

Membrane Society of Japan

Filtration Society Japan Association (FSJA)

The Membrane Society of Korea

The Filtration Society

American Filtration & Separations Society

American Membrane Technology Association (AMTA)

Association of the Nonwoven Fabrics Industry (INDA)

The Fiber Society

Filter Manufacturers Council

International Desalination Association

The National Air Filtration Association (NAFA)

North American Membrane Society

Process Equipment Manufacturers' Association (PEMA)

 

 

 

Online Magazines

AVR - Allgemeiner Vliesstoff-Report, World-wide Nonwovens Industry

Filtration + Separation

Filtration News

Solid-Liquid Separation

European Pharmaceutical Manufacturer

 

 

 

Exhibitions and conferences

World Filtation Congress

Filtration & Separation Asia

Filtech

Filtrex