| 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 |
| B | |
| Backwash | Flow through a filter in the reverse direction |
| Bacteria | A large variety of single celled micro-organisms 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 permeable 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 integrity 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 |
| 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 chlorine 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 absorbent to be in contact with a liquid to remove a contaminant |
| Contaminant | Particles in a fluid which are undesirable |
| 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 |
| 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 occurring 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. |
| 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. |
| 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 assist in filtration |
| Filter Cake | The accumulation of solids on a filter septum which builds up and assists filtration |
| Filter Medium (Media plural form) |
A permeable 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 membrane |
| Frazier | A test which measures the air permeability of a filter septum. |
| Free Water | Refers to captured water in a separation system. Usually a coalescer. |
| 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 contaminant as determined by suspended solids analysis. |
| 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. |
| 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. |
| L | |
| Laminar Flow | A fluid flow which is devoid of any turbulence |
| 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. |
| N | |
| Nanofiltration (NF) | A cross-flow 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. |
| 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. |
| 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. |
| 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. |
| 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 |
| T | |
| Thixotropic Flow | Fluids which show a time dependent 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 |
| U | |
| Ultrafiltration (UF) | Cross flow semipermiable membrane separation of particles from 10 Angstroms to 0.2 micron. |
| Ultraviolet (UV) | Radiation which has a wavelength 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. |
| 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. |
| 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. |
