| A |
| Absolute Rating |
Micron size of a particle that will be removed by a filter at the stated efficiency |
| Absorption |
The movement of a liquid or gas into the pores of a solid. |
| Adsorption |
A liquid or gas being held on the surface of a solid |
| ACFM |
Actual Cubic feet per minute |
| ASME Code |
Fabrication standards of American Society of Mechanical Engineers |
| ASTM |
The organization called "The American Society for Testing and Materials" |
| Activated Carbon |
Granular carbon that has been treated to enable the absorption of odor, taste and chlorine |
| Aeration |
The mixing of air with water to achieve mixing or oxidation |
| Aerosol |
The dispersion of solid or liquid particles in air that will stay dispersed for a period of time |
| Agglomerate |
The aggregation of smaller particles into a larger one |
| Alkalinity |
The ability to neutralize acids. Usual pH is between 7 and 14. |
| Anion |
An atomic particle with a negative charge |
| Antimicrobial |
Any compound that kills or inhibits micro-organisms on contact |
| Atmosphere |
A unit of measure of pressure |
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| B |
| Backwash |
Flow through a filter in the reverse direction |
| Bacteria |
A large variety of single celled micro-organisims that lack a nucleus. |
| Baffle |
A device which is used in filter housings to divert the incoming stream to provide uniform flow |
| Bar |
A designation of pressure units; 1 Bar = 14.5 psi |
| Beta Ratio |
The filtration ratio which is the ratio of the number of given size particles in the feed divided by the number of particles of the given size in the effluent |
| Binders |
In filtration, these are the compounds which "bind" the fibers together |
| Blind Spots |
Areas of a filter media that will not permit flow due to plugging or blinding. |
| Blinding |
The pores, or openings of the filter media, are blocked which prevents flow |
| Body Feed |
The continuous feeding of a filter aid to the influent stream to create a permiable filter cake |
| Bridging |
The formation of a particle "arch" over an filter pore opening |
| Bubble Point |
The pressure drop required to expel the first steady stream of bubbles from a wetted filter |
| Bubble Point Test |
The intergrity test for filters that is non-destructive and indicative of the pore size rating. |
| Burst Strength |
The ability of a filter medium to resist rupture by pressure applied in the normal direction of flow. |
| Bypass |
A fluid flowing through a passage other than through the filter media |
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| C |
| Cake |
The surface accumulation of solids on a filter medium. |
| Cartridge Filter |
A cylindrical element, usually disposable, which is inserted into a filter housing. |
| Cation |
An atomic particle with a positive charge |
| Caustic Soda |
A trade name for Sodium Hydroxide, NaOH. |
| Cellulose |
A fibrous, vegetable material used as a filter medium |
| CFM |
Cubic Feet Per Minute |
| Chelating Agent |
A soluble, organic molecule which will hold metal ions in solution |
| Chloramine |
A chlorine/ammonia compound which demonstrates greater persistence than chlorine alone. |
| Chorination |
The addition of small amounts of chorine gas to water to disinfect the water |
| Chlorine |
A chemical compound, Cl2, used in small amounts to disinfect or oxidize. |
| CIP (Clean-In-Place) |
The chemical cleaning applied to a fouled membrane to restore it to its original flux performance |
| Clarification/Clarity |
Filtration of fluids containing a small amounts of particles |
| Classification |
The separation or arrangement of particles by size |
| Collapse Pressure |
Pressure which is great enough to collapse a filter |
| Colloid |
Submicron particles held in suspension in fluid and will not settle out |
| Compressibility |
The degree of change in volume when subjected to pressure |
| Concentrate (Retentate) |
The non-filtered stream leaving a membrane filtration system. |
| Concentration |
1) The amount of material in a unit of volume; or 2) To increase the dissolved material per unit of volume. |
| Concentration Factor (CF) |
Ratio of feed mass to concentrate mass. |
| Concentration Polarization |
An accumulation of excess particles in a thin layer adjacent to the membrane surface. |
| Condensate |
Vapor which has coalesced into a liquid state. |
| Conductivity |
The ability of a liquid to conduct an electrical current. The inverse of resistivity. |
| Contact Time |
The time it takes an absorbant to be in contact with a liquid to remove a contaminant |
| Contaminant |
Particles in a fluid which are undesireable |
| Cross-flow Filtration |
A mode of filtration in which the pressurized feed stream flows parallel to the membrane surface |
| Cross-flow Velocity |
Average velocity of the bulk cross flow parallel to the membrane surface. |
| Crypto |
Cryptosporidium, a parasite found in water |
| Cycle (Length) |
The duration of a filters service before regeneration or replacement is required |
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| D |
| Deionization (DI) |
The process of removing ions from a fluid by an insoluble exchange medium |
| Density |
Mass per unit volume |
| Depth Media |
Filtration media which removes particles within the media as opposed to the surface |
| Diatomaceous Earth (DE) |
A naturally occuring soft, chalk like sedimentary rock which crumbles easily to a powder which is used as a filter medium. |
Differential Pressure
(Delta P) |
The difference in pressure between two points in a filter system, normally the inlet and outlet nozzles. |
Diffusion-Limited Flux
(Jmax) |
A limit where the flux will no longer increase proportionally with pressure. |
| Dirt Holding Capacity |
The weight of material retained by a filter to a given pressure drop |
| Dirty Differential Pressure |
The delta P at which the cartridge will require maintenance or changeout |
| Disinfectant |
A chemical compound which is used to sanitize tanks, pumps and piping. |
| Dissolved Solids |
After filtering a fluid, this is the residual solids left after evaporation |
| DOP Test |
Dioctyl phthalate (DOP). Standard test to qualify HEPA Filter @ .3um @ 99.97% |
| Double Open End (DOE) |
A filter which requires a housing with knife edge seals to seal against the flat gaskets at both ends of the filter element. |
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| E |
| Efficiency |
Under given conditions of contaminant and concentration, it is the percent ability to remove the contaminant. |
| Effluent |
The name of the stream as it exits a treatment system |
| Emulsion |
A suspension of small liquid droplets within a second liquid that will not mix |
| Element |
The unit comprised of the filtration medium and it’s support structure that goes into a filter housing. Also referred to as the cartridge, filter tube or candle. |
| End Cap |
The closed end of a filter element, pipe or housing. It may be closed or ported. |
| Effective Area |
The total area of medium exposed to flow and usable for separation |
| Endotoxin |
A lipopolysaccharide from the walls of a nonviable bacterium; also, a pyrogen |
| Endotoxin Units (EDU) |
A unit of measure (EDU) used to express endotoxin (pyrogen) levels |
| EPA |
United States Environmental Protection Agency |
| Extractables |
In filtration, these are compound that leach into the filtrate. |
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| F |
| FDA |
United States Food and Drug Administration |
| Feed |
The input fluid to a treatment process |
| Filter |
The complete device which supports the medium carrying out the process of filtration. The term includes the housing and the element. |
| Filter Aid |
A precoat of insoluble media on a filter septum to assit in filtration |
| Filter Cake |
The accumulation of solids on a filter septum which builds up and assists filtration |
Filter Medium
(Media plural form) |
A permiable media which permits fluid flow through it and retains particles |
| Filtrate |
A fluid which has been through a filter medium |
| Filtration |
The process of removing solids from a fluid stream by means of a septum. |
| Filtration Efficiency |
Under given conditions of contaminant and concentration, it is the percent ability to remove the contaminant. |
| Filtration Rate |
The volume of fluid that passes through a given area of a filter in a specified time. |
| Flux (J) |
Permeate flow rate per unit of membrane area. (e.g., GPM/ft.2/day). |
| Fouling |
A deposition of retained solids on a membrane surface or in the pore structure of the memebrane |
| Frazier |
A test which measures the air permiability of a filter septum. |
| Free Water |
Refers to captured water in a separation system. Usually a coalescer. |
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| G |
| Gauge |
The thickness of steel sheet or wire diameter. |
| Gauge Pressure |
A pressure greater than atmospheric pressure |
| Gel |
A deformable particle that can pass through a filter |
| Giardia Cyst |
A waterborne parasite which causes problems with the digestive system |
| Graded Density |
A filter media that is comprised of more open pore sizes on the outside and tighter pore sizes near the core |
| Gravimetric Efficiency |
Weight of contaminent as determined by suspended solids analysis. |
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| H |
| Head |
The end closure of a filter housing which may contain ports; or the measurement of pressure in a column of water. |
| Housing |
A vessel which has various ports and is configured to direct the flow through a filter cartridge. |
| Hydrophilic |
A strong affinity for water |
| Hydrophobic |
Lacking an affinity for water |
| Hydrostatic Test |
A test to confirm the integrity of a filter pressure vessel or housing. The common test is to pressurize the vessel to 1 1/2 times the design pressure rating. |
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| I |
| Immiscible |
Incapable of being mixed or blended together. |
| Influent |
The fluid which enters a filter. |
| In-line Filter |
A filter housing whose inlet, filter element and outlet are on a single axis. |
| Ion |
A charged atom or molecule. |
| Ion Exchange |
A chemical process whereby ions are removed from solution on to an insoluble polymer and replaced by preferred ions. |
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| L |
| Laminar Flow |
A fluid flow which is devoid of any turbulance |
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| M |
Maximum Differential
Pressure |
The Max Delta P of a system at which it can safely operate. |
| Mean Filtration Rating |
The average size of the pores in a filter septum |
| Media (Medium) |
The functional portion in a filter element that separates the solids |
| Media Migration |
Materials of construction of the filter sloughing into the filtration stream |
| Membrane |
An angstrom's thick membrane on a substrate with a controlled number of pores. |
| Membrane Area |
The total surface of a membrane usually expressed in square feet or square meters. |
| Mesh |
The number of strands in a linear inch of woven filter fabric. |
| Microfiltration (MF) |
A filter septum that is designed to remove particles that are 0.1 to 3 microns on size. |
| Micron |
A metric measurement equivalent to 10-6 meters. One inch is equivalent to 25,400 microns. |
| Micron Rating |
The measurement of the effectiveness of a given element. |
| Mist |
Small particle liquid dispersion often caused by condensation |
| Mixed Bed |
An ion exchange resin bed which has a stoichiometric amount of cation and anion resins. |
| Module |
A membrane element with it housing. |
| Molecular Weight |
The sum of the atomic weights of the atoms which comprise a molecule. |
Molecular Weight Cutoff
(MWCO) |
Molecular weight value where 90 percent of the feed stream solutes greater than the MWCO will be rejected. |
| Molecule |
The smallest particles of pure chemical substances that still retain their composition and chemical properties. |
| Multi-pass Process |
A filtration stream which repeatedly passes through a filter medium, as in a closed loop. |
| Multi-pass Test |
A destructive test which is used to determine the Beta ratio of a filter medium. |
| Multifilament |
The number of continuous strands that are twisted together to form a yarn. |
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| N |
| Nanofiltration (NF) |
A crossflow filtration process which removes solids whose molecular weight is in the 250 to 1000 molecular weight range. |
Nephelometric Turbidity
Units (NTU) |
The units of the test that incorporates use of light scattering to determine the turbidity of the water |
| Nominal Rating |
The arbitrary micron removal rating assigned by the filter manufacturer. |
| Nonwoven |
The random ordered fibers held together by a binder to make a filter paper or cloth |
| Normal Flow |
Flow that is perpendicular to the filter medium as opposed to tangential. |
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| O |
| Osmosis |
The flow of water from a less concentrated solution to a more concentrated solution through a semipermiable membrane. |
| Ouside-In Flow |
The typical flow of a fluid perpendicular to the axis of a filter cartridge. |
| Ozonator |
A device which generates ozone by passing a high voltage through air or oxygen. |
| Ozone (O3) |
An unstable form of oxygen that is used for oxidizing and sanitizing. |
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| P |
| Particle Filtration (PF) |
A filter medium which removes particles in the 1 to 75 micron range. |
Particle Removal
Efficiency |
The removal of particles as a function of size as determined by counting individual particles. |
| Particulate |
Pieces of solid that are individual and minute. |
| PED 97/23/EC |
Pressure Equipment Directives - European Commonwealth directives on the design and fabrication of pressure vessels. |
| Permeability |
Membrane flux divided by the average trans-membrane pressure. |
| Permeate (Filtrate) |
The filtered stream leaving a membrane filtration system. |
| Permeator |
The thousands of hollow fibers which comprise the makeup of a hollow fiber element. |
| pH |
The negative log of the Hydrogen ion concentration used to indicate acidity or basisity. |
| Polymer |
A large molecular mass comprised of repeating structural units or monomers. |
| Pore |
An opening in a filter septum. |
| Porosity |
A measurement of the open or porous portion of a filter septum |
| ppb |
part per billion |
| ppm |
part per million |
| Precipitate |
A insoluble solid that is the result of a chemical reaction. |
Pressure Drop
(See Differential Pressure) |
The difference in pressure between two points. |
| psi |
Pounds per square inch |
| psid |
Delta pounds per square inch |
| psig |
Pounds per square inch, gauge |
| Pyrogen |
A molecule or particle which can produce a fever in mammals. |
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| R |
| Reagent Grade Water (ASTM) |
Standards for water prepared by the ASTM depending on the intended use of the water. |
| Recirculation |
The continuous flow of a fluid either across a membrane, or through a system. |
| Recovery (R) |
Ratio of permeate mass to feed mass, usually expressed as a percentage. |
| Regeneration |
Replacement of the ions removed from the process water or stream |
| Rejection (g) |
A measure of how well a membrane system retrains or allows passage of a solute. |
| Resins |
Ion Exchange resin polymer beads with functional groups to exchange ions. |
| Resistivity |
The ability of a fluid to resist the flow of electricity. An indication of purity in water. |
| Reverse Osmosis (RO) |
Overcoming the natural osmotic pressure to make water flow from the more concentrated solution to the less concentrated solution. |
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| S |
| Saturation |
For a given temperature and pressure, it is the concentration of solute that will no longer be soluble in the solvent. |
| Scaling |
The build up of salts, primarily hardness, on the walls of pipes, and tanks. |
| SCFM |
Standard Cubic Feet per minute |
| Screen |
Another term for a filter septum |
| Semipermeable |
A membrane property that permits solvent to pass through but not all the solute. |
| Septum/Septa |
A filter surface |
| Side Seal |
The closure of the filter media that is parallel to the axis of the filter element. |
| Silt Density Index (SDI) |
A test which indicates the amount of suspended solids in a feed water |
| Single Open End (SOE) |
A filter element in which the flow passes through the filter and out one end; the other end being closed. |
| Single Pass Process |
A process in which the fluid passes through the media only once. |
| Solutes |
That which is dissolved in a solvent |
| Sparger |
A device which introduces a gas into a liquid to mix the liquid or dissolve the gas in the liquid. |
| Specific Gravity |
The ratio of the mass of a solid or liquid to the mass of an equal volume of water. |
| Stage |
One or more membrane modules sharing the same circulation pump. |
| Strainer |
A filter element or medium which has a pore size of greater than 40 microns. |
| Surface Media |
Very thin filter media that provide a very high flow rate. |
| Suspended Solids |
Solid material which is held in suspension in a solvent |
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| T |
| Thixotropic Flow |
Fluids which show a time dependant change in viscosity when shear stress is applied |
| Throughput |
The total volume of a fluid that is processed by a filter before the filter is replaced. |
| Total Dissolved Solids (TDS) |
The total amount of solids dissolved in a solvent |
Total Organic Carbon
(TOC) |
The total amount of carbon compounds in a water sample |
| Total Solids (TS) |
The total amount of solids both dissolved and suspended in a solvent |
| Total Suspended Solids (TSS) |
The total amount of solids that a not dissolved in a solvent |
| Trans-Membrane Pressure (TMP) |
The pressure differential driving permeate through a membrane. |
| Turbidity |
The cloudiness in a solvent that is caused by suspended solids that will not settle. |
| Turbidity Units |
The units of measure of the ability of a light beam to be transmitted through a fluid. |
| Turbidimetric Efficiency |
The percentage reduction of the haze in a fluid. |
| Turbulent Flow |
Flow at which laminar flow is exceeded |
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| U |
| Ultrafiltration (UF) |
Cross flow semipermiable membrane separation of particles from 10 Angstroms to 0.2 micron. |
| Ultraviolet (UV) |
Radiation which has a wavelenght that is shorter than visible light but longer than soft X-rays. |
| Uniform Density |
Having the same weight per unit volume of a septum from its influent to effluent ends. |
| Unloading |
The release of previously removed contaminants from a filter by an increase in pressure. |
| United States Pharmacopoeia (USP) |
The manual of standards for the pharmaceutical industry established by the US Congress. |
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| V |
| Validation |
In the pharmaceutical industry it is the process and record keeping necessary to prove compliance. |
| Velocity |
The amount of free air passing through a filter panel. |
| Vessel |
A device which is designed to hold filter elements or bags. |
| Viscosity |
The resistance to flow demonstrated by some fluids |
| Void |
In a filter septum, it is the openings or pores. |
Volatile Organic
Compound (VOC) |
An organic compound which will develop a vapor pressure from solution. |
| Volume Reduction Factor (VRF) |
Ratio of feed volume to concentrate volume. |
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| W |
| Water For Injection (WFI) |
Water which meets the standard of the USP for medical injection and irrigation. |
| Water Hammer |
Pressure variations caused by quick acting valves on a non-compressible fluid. |
| Water Point |
Permeability when operating the system on clean water at standard reference conditions. |
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| Common Conversions |
14.5 psig = 1 Bar = 1.02 kg/cm2 = 0.1 MPa
1 meter = 3.28 feet
1 gfd = 1.7 lmh
1 m3/hr = 4.4 gpm
1 US gallon = 3.785 liters
1 horsepower = 0.746 Kw
1 psi = 2.31 feet of water column
1 ppm = 1 mg/liter
1 m3 = 1000 liters = 1 metric ton |
