glossary of process filtration terminology
Absolute Filtration Rating : Filtration industry trade terminology that guarantees higher particle removal efficiencies for a filter media. Different manufacturers can define "absolute" differently. An absolute rating generally will range from 98% efficiency to 99.99% efficiency and can be tested in a variety of different operating conditions. Absorption : The penetration of one substance into the inner structure of another. In filtration and separation, absorption is when a liquid or gas mechanically penetrates fibers or particles causing them to swell to remove the liquid or gas. Contrasted with adsorption.
Absorption tower : a device used for gas purification.
Absolute pressure : pressure above absolute vacuum pressure. Contrast with gauge pressure.
Absolute viscosity : dynamic viscosity, in centipoise. Greek symbol µ Mu.
AC Test Dust : former name for test dust used in filter efficiency testing.
ACFTD : AC Fine Test Dust
Acid : a compound containing hydrogen that in water forms H3O+ ions, usually written as H+ ions. Acids have a pH less of 6 or less. Sour taste.
Activated carbon : a common adsorbent formed from carbonaceous material such as wood that is treated with superheated steam or carbon dioxide.
Activated clay : An adsorbent. See Clay treatment.
ACFM : actual cubic feet per minute. This is the SCFM (the standard cubic feet per minute) corrected for temperature and pressure.
Adhesion : the attraction between molecules that causes matter to cling to or stick to other matter.
Adsorbtion : When a liquid mechanically holds to the surface of fibers or particles to remove the liquid.
Aerosols : Liquid droplets or particles dispersed in air or gases with a particle size of between 0.01µm to 100um, small enough to be in dispersion and to be difficult to remove by gravity separation alone. Aerosols are commonly separated with coalescers.
Airlaying : process of dispensing fibers into a stream of air and condensing them onto a moving screen through the use of air pressure or a vacuum, thereby creating a web.
Airlaid : sheet or web of fibers created by airlaying.
Air permeability : ease in which air can pass through a fabric. In air or gas filtration, a measurement of the openness of a filter media to flow of air or gas. The standard test for permeability is the Frazier test.
Alkali : any substances with an abundance of OH- ions in water with a pH of greater than 7. React with acids to form salts. Bitter taste.
Alumina, activated : granular aluminum oxide used as an adsorbent.
Ambient : room temperature. "Ambient" may also refer to the protective cover over a filter element.
Amine : a class of organic compounds that are basic in nature and combine with acids to form salts. Amines are used to sweeten hydrocarbons.
Antifoaming Agent : additive that reduces the formation of bubbles within or on the surface of a liquid. Can be a surfactant affecting coalescence.
Anthracite : a form of coal with a high carbon content.
API : American Petroleum Institute.
API gravity : measurement of density for hydrocarbons, particularly crude oils. API gravity numbers range from 0-100 and decrease as density increases.
AIChE : American Institute of Chemical Engineers.
ANSI : American National Standards Institute.
Aramid : In filter media, the generic name for a special group of synthetic fibres (aromatic polyamide) having high strength; examples are "Kevlar" and "Twaron".
Aromatics : A major class of organic compounds derived from hydrocarbons that contain an unsaturated ring of carbon atoms. Included are benzene, naphthalene, anthracene and their derivatives. Aromatics are highly reactive and are strong solvents.
ASHRAE : American Society of Heating, Refrigerating, and Air-Conditioning Engineers.
ASME Code : American Society of Mechanical Engineers Boiler and Pressure Vessel Code Certification. For filter vessels, this usually refers to the standard for unfired pressure vessels, Section VIII.
ASTM : American Society for Testing and Materials
Atmosphere : at sea level 14.7 psi.
Attenuation : drawing or pulling molten polymer into a reduced diameter filament or fiber, as in the formation of a meltblown fiber of a fiber from molten glass.
Autoclave : An apparatus into which usually moist heat (steam) under pressure is introduced to sterilize or decontaminate materials placed within a strong, closed, pressure vessel. Widely used for sterilizing filter elements and housings for sterile uses.
Backwash : when filtrate flow is reversed back through a filter media or a sand media to clean the media.
Baffle : a deflector plate at the inlet of a filter or coalescer vessel to deflect flow to protect filters from damage and to provide flow distribution.
Bar : a measurement of pressure. 1 bar = 14.5 psi.
Barometric pressure : atmospheric pressure above sea level.
Base : any substances with an abundance of OH- ions in water with a pH of greater than 7. React with acids to form salts.
Basis weight : in filter media, mass per unit area, such as ounces per square yard or grams per square meter.
Batting : soft, bulky assembly of fibers, usually carded.
Bernoulli's Theorem : formula for expressing the total head in a fluid in a pipe, relating the head to the sum of the elevation head, the pressure head, the velocity head, accounting for friction losses.
Beta Ratio : an efficiency rating for liquid filters that measures particles in the feed of the specified micron size and larger compared to the particles in the filtrate of the specified micron size and larger. For example, a beta ratio of 100 at 1µm means that for every 100 particles 1µm or larger upstream of the filter there is only one particle 1µm or larger downstream of the filter. Beta 100 is 99% efficiency. Beta 5000 is 99.98% efficiency. Beta ratios are measured in a multi-pass test and are most commonly performed in either water or hydraulic oil. Test methods for hydraulic oil beta ratios are more standardized but for water beta ratio test methods vary significantly.
Bicomponent Fibers : fibers that are comprised of two polymeric compounds. They can be arranged in a core sheath, side-by-side, a matrix, or 'islands in the sea' configuration. These configurations are chosen so that one polymer softens at a lower temperature than the other in order to maintain structural integrity and to give the fabric desired characteristics.
Binders : In filter media, adhesive chemicals used to hold fibers together in a filter media or other web. Commonly used in paper and microfiberglass pleated medias and in glass tubes used in coalescing elements.
Binder Content : usually given as a percentage of the fabric weight, this the amount of adhesive mass used to bond the fibers together in a web.
Binder Fiber : usually these are thermoplastic fibers that have a lower softening (temperature) point than the other fibers used to create the web such as Remay.
Blend : combination of two or more fiber types in a fabric.
Blinding : premature plugging of pore structure by contaminant.
BOD : Biochemical Oxygen Demand: a measure of the organic material in water. BOD measures the amount of oxygen required for bacteria to degrade the organics in the water.
Boyle's Law : the volume of a gas varies inversely with pressure.
Bridging : where filter cake forms an arch over the tops of pleats in a pleated filter element. Bridging reduces flow and increases pressure drop and is usually caused by pleats being packed tightly in a stream with large particles. Usually particles smaller than 30µm will not bridge a pleated filter.
Brownian movement : The continuous zig-zag motion of particles or aerosols in suspension. The motion is caused by the impact of the molecules of the fluid or gas upon the particles. Brownian movement can be significant for the capture of small particles and aerosols by a filter media.
BTEX : benzene, toluene, ethylbenzene and xylene.
Bubble point : either a test of the largest pore size in a filter media or an integrity test for a filter cartridge.
Burst test : a measurement of an air filter medias' resistance to tearing/bursting. The industry standard test is a Mullen Burst test.
Cake : particles or precoat that form on the surface of a filter media. At optimum, pleated filters will build a cake before surface blinding occurs.
Caustic soda : Sodium hydroxide (NaOH)
Calender : machine used to bond fiber web materials or sheets of fabrics or film to each other. Two or more heavy cylinders impart heat and pressure as the sheets are drawn between them. The cylinders can have surface features required in the fabric (patterns, smooth, porous).
Calendering : a process of compacting, embossing, and bonding flat sheets of fibers. Commonly, large rollers apply heat and/or pressure to the web.
Caustic : 1) sodium hydroxide. 2) any strong alkali.
Caustic soda : sodium hydroxide.
Caustic treatment : a sweetening process for liquid hydrocarbons that usually uses sodium hydroxide or potassium hydroxide.
Carbon black : an industrially manufactured form of carbon of very small particle size.
Card : machine that separates fibers, removes impurities, aligns fibers and delivers them for further separation or for airlaying. The machine is a series of rolls and drums (called Cards) with projecting wires or teeth that will lay the fibers in the largely the same direction.
Carry-over : the transfer of material (specimen or reagents) from one container, or from one reaction mixture, to another one.
Catalytic reforming : A process for increasing the octane number of naphthas.
Catalyst : a substance that increases the rate of a reaction
Cationic : chemical that has a positive electrical charge.
Cellulose : a filter media made of organic fibers such as wood, cotton, grass, and plant pulp.
Cellulosic Fibers : polymers of the cellulose molecule and the product of fibrous plants. Cotton plants grow separate cellulose fibers. Wood pulp is made by mechanically or chemically separating wood fibers. Other sources include Flax, Manila, Ramie and Jute.
Centipoise (cP) : 1/100th of a poise, the metric measurement of absolute viscosity commonly measured in dyne-seconds per square centimeter. Centipoise measure absolute viscosity, that is without consideration of the density of the fluids.
Centistokes (cS) : 1/100th of a stoke, a unit of kinematic viscosity. Equal the viscosity in centipoise divided by the density of the fluid in grams per cubic centimeter at the same temperature.
Chemical Absorption : one of the methods for sweetening hydrocarbons. In natural gas, weak basic solutions such as amines often remove acidic sulfur compounds and carbon dioxide. In liquid hydrocarbons, such as fuels and petrochemical intermediates, a strong caustic solution such as sodium hydroxide often removes acidic sulfur compounds.
CIP : abbreviation for Clean-In-Place.
CFM : cubic feet per minute.
Clay Treatment : also known as clay filtration. When properly pre-treated, clays becomes very attracted to "polar" materials and will actually attract and chemically attach to many impurities, thus removing them. Commonly used to remove organic acids from hydrocarbons.
Closure : the head or top of a filter vessel. Closure design can substantially affect the difficulty changing filters.
Coagulation : the aggregation of suspended solids or semi-solids. Coagulation is often aided by the addition of an electrolyte, mechanical agitation, or removal of stabilizing ions.
Cohesion : the ability of a substance to stick to itself and pull itself together.
Colloidal suspension : a liquid or gas with suspended particles ranging from 0.1µm to 0.001µm that commonly are removed with membranes or distillation.
Compressibility : the compaction of filter cake under pressure.
Concentrate : In Crossflow filtration, the continuous stream of product and contaminant that recirculates and contains impurities rejected by the membrane.
Condensate : 1) a low-density, high-API gravity liquid hydrocarbon phase that generally occurs in association with natural gas.
2) Any liquid, such as water, from evaporation and condensation.
Contact Angle : the wettability of a material. A drop of liquid on the material will be flattened out (higher wettability) or round (more water-repellant) depending on the wettability.
Contact time : the residence time a liquid is in contact with an absorbent or adsorbent.
Continuous phase : product or liquid that you want to retain.
Co-Polymer : polymer chain comprised of monomeric units from more than one monomer (ie. vinyl acetate).
Corrugated plate interceptor (CPI) : oilpatch separator that removes water from crude oil based on the difference in specific gravities using corrugated plates.
Cracking : the thermal or catalytic decomposition of a compound such as a hydrocarbon into chemical species of smaller molecular weight.
Critical Device : in pharmaceutical filtration, a point of use filter that directly ensures that a GMP Critical Parameter is maintained within predetermined limits. A malfunction of such a device would place product quality directly at risk.
Cryptosporidium parvum : A protozoa parasite common to humans and cattle.
Cubic Foot : the amount of liquid or gas to fill an area one square foot of area. In liquids, about 7.5 gallons.
Darcy's Formula : equation for pressure drop, usually expressed in feet of fluid or pounds per square inch.
DE : abbreviation for Diatomaceous Earth.Fossilized skeletons of minute, prehistoric aquatic plants used as a filter aid.
Deformable particles : solids that are soft particles that can cause blinding in a filter cake and can extrude through a filter media.
De-ionized : without ions - usually refers to very pure water.
Demister : Apparatus made of wire mesh or glass fiber used to help remove mist.
Denier : a measurement of fiber diameter equal to the mass in grams of 9,000 meters of material. Low numbers indicate fine fiber sizes, high numbers indicate coarse fibers.
Density : mass divided by volume, also referred to as weight density, commonly expressed in pounds per cubic foot. (symbol: ? pronounced rho)
Desiccant : an adsorbent substance such as silica gel, activated alumina, calcium chloride, or zinc chloride.
Dewatering : removal of water from a suspension or sludge by filtration or clarification. Centrifuges, press plates, leaf filters, and drum filters are some of the common dewatering methods.
Delta : Greek symbol for differential.
dP : "Delta P" differential pressure across a filter. The difference between the pressure upstream and downstream of a filter housing.
Differential pressure gauges : pressure sensors that measure the difference between pressure upstream and downstream of a filter housing. Used to optimize change outs of filter elements.
Diffusion : spreading or scattering of a gaseous or liquid material.
Dirt holding capacity : a measurement of the service life of a filter. Dirt holding tests measure the amount of test dust or test beads that are added to the feed being filtered before a given differential pressure is reached, often in multipass tests. Test standards vary significantly between different manufacturers.
Dissolved liquids : liquids that are in solution and cannot be removed by mechanical means such as coalescing or adsorption.
Dirt loading : see Dirt holding capacity.
Discontinuous phase : contaminant in a coalescing system.
Dispersion : distribution of small particles or aerosols in medium, such as a Colloidal suspension.
Dissolved oil : emulsified or dissolved oil that cannot be removed by coalescence.
Dissolved solids : Solids that are in solution and cannot be removed by mechanical means such as filtration. (Membranes can remove some dissolved solids.)
Distillation : a process where a fluid is heated above it's boiling point and turned to a vapour. The vapour passes into a condenser and is turned back into a liquid. Impurities present in the original fluid remain behind, allowing the distilled fluid to be purified.
Drylaid Nonwoven : a nonwoven fabric such as a filter medium made from dry fibers, as contrasted to a Wetlaid Nonwoven.
Duplex : a filter assembly where two or more filter vessels are set in parallel so that one set of filter cartridges can be changed while the other elements are still on-line.
Effective filtration area : the total area of the filter media exposed to flow in a filter element. In pleated cartridges with a surface media, the effective area is the surface area of the pleated media.
Efficiency : the ability of a filter to remove contaminant of a stated size and larger, usually stated as a percentage. Efficiencies are measured under a variety of test conditions and, therefore, often are not a good measure to compare the effectiveness of filters or coalescers.
Effluent : waste that is discharged, e.g. from chemical plants or waste water treatment plants.
Emulsifier : a surfactant that helps create an emulsion.
Emulsion : a stable mixture of two liquids held in suspension.
Endotoxins : pyrogens.
Entrainment : carry-over from coalescing, evaporation etc.
Epoxy compounds : thermoplastic adhesive compounds in which an oxygen atom is directly attached carbon atoms of a carbon chain or ring system; thus cyclic ethers. Epoxy adhesives may have broad chemical compatibilities.
Extractables : a pharmaceutical industry term for foreign substances that are leached or dissolved by water or process streams from the materials of construction used in filters and other wetted surfaces. Extractables (oxidizable extracts) for pharmaceutical grade filter elements are usually given in mg/TIE.
Feed : inlet solution to a filter system.
Felt : sheet of matted fibers (wool or fur) bonded together by a chemical process and the application of water, heat and pressure. (See also Needlefelt, which is more commonly used in filtration than a felt.)
Fiber Distribution : the orientation of fibers in a web (parallel, random, etc.) and their uniformity.
Fiber migration : fibrous filter media material released into the stream.
Filteraid : a polymer added to aid in filtration or flocculation.
Filter cake : either a pre-coat or particulate that forms on the surface of a filter media.
Filtrate : any liquid that has passed through a filter media.
Filtration : A process for removing particles from a solution by passing it through a porous structure or medium, such as a screen, membrane, sand or gravel.
Filtration rate : in pleated filters, the volume of liquid or gas filtered per unit of surface area of the filter media in a stated period of time.
Float cell : a method of filtration where natural gas is permeated through produced hydrocarbons to remove particulate and bulk hydrocarbons.
Flow rate : in filtration, the volume of a liquid per unit of time that flows in a system, most commonly expressed in gallons per minute (gpm), liters per day (lpd), or cubic feet per minute (cfm).
Flux rate or Filtration rate : flow rate per unit surface area, usually gallons per square foot of filter media per minute, hour, or day. Flux rate substantially affects the performance of a filter cartridge or coalescing element. Also known as filtration rate.
Fouling : where particulate, colloidal material, bacteria, or scale form on a filter media shortening the life of the filter.
Frazier : in air or gas filtration, a measurement of the air permeability of a filter media.
Free oil : oil that is not dissolved and not emulsified so that it separates by gravity separation in approximately 5 to 10 minutes.
FTU : Formazine Turbidity Units - measurement of turbidity.
Fuller's Earth : a common filter clay.
Gauge pressure : pressure above atmospheric pressure. Contrast with absolute pressure.
Glycol : dihydric alcohols used for dewatering. Common glycols are triethylene glycol (TEG) and ethylene glycol (EG).
Gravity filter : 1) a bed filter, normally for water and wastewater, that operates at atmospheric pressure.
2) any filter that separates by settling by gravity.
Guardia : Giardia lamblia (intestinalis) is a single celled animal, i.e., a protozoa parasite called found in water that causes diarrhea.
Headloss : pressure drop, often measured in inches of water column.
Homopolymer : polymer chain made from only one monomer.
Hot-melt Adhesive : a thermoplastic adhesive material that melts quickly when heated and sets firmly when cooled. In filter elements, often a polyester or polyamide polymers are used to bond end caps or to seal sideseams. Hot-melt fabrics are also used to laminate some filter medias.
Hydrophilic : water accepting. Whether a media is hydrophilic is significant for tighter filter medias filtering water and for coalescers separating water from another fluid. Also known as hydrophilicity. Hydrophilic filter medias have high surface tensions and tight hydrophobic filter medias may have to be "wetted out" with a surface wetting agent such as isopropyl alcohol before filtering water.
Hydrophobic : water rejecting. Whether a media is hydrophobic is significant for tighter filter medias filtering water and for coalescers separating water from another fluid. Hydrophobic materials possess low surface tension values and lack active groups in their surface chemistry to bond with hydrogen in water.
Hydroscopic : hydrophilic.
Hygroscopic : a substance that adsorbs moisture. Desiccants are hygroscopic.
Hydrocracking : the thermal decomposition of heavy (high molecular weight) hydrocarbons to smaller (low molecular weight) hydrocarbons; high pressures of hydrogen and a special catalyst are employed. Sulfur compounds in the fuel are reduced to H2S, and the final hydrocarbon product can be obtained relatively sulfur-free.
Hydrocarbons : compounds consisting of hydrogen and carbon.
Hydrogen peroxide : strong oxidizing agent. H2O2.
Hydrogen Sulfide : H2S, sulfur acid compounds found in crude oil and natural gas.
Imbibition : capacity of a fabric to hold liquids.
Impaction : capture process where inertia causes the particle or aerosol to strike the media surface. Considered most applicable to particles 1µm and larger.
Injection well : 1) a waste water well.
2) oilfield wells used either for disposal of salt water or for secondary well stimulation by the injection of either gas or water.
Interception : capture process where pore size causes particle or aerosol to slow near a media wall. Considered most applicable to particles 0.1µm to 2µm.
Inside-out-flow : a filter element that flows from the outside to the inside. This is less common for filter cartridges and more common for coalescers.
Interfacial Tension - (IFT) the measurement of the forces that act across the interface of two liquids that affect the stability of the interface.
Inside-out flow : flow through a filter element or coalescer that flows from inside of the element to the outside. There often is a core or similar structure on the outside of the element to resist rupture due to pressure.
Intermediates : organic compounds which are precursors to a desired product; ethylene is an intermediate for polyethylene.
Ion : an atom, molecule or radical which has become electrically charged by virtue of having either gained or lost an electron. When an electron is gained the ion is negatively charged and is called an anion. A positively charged ion is called a cation.
IPA : isopropyl alcohol.
Iron Sulfide : a common contaminant in hydrocarbons that can have a significant particle distribution at a small size, 0.5µm to 10µm.
I.S.O. Test Dust : test dust used in filter efficiency tests. Available in Fine and Coarse.
JTU : Jackson Turbidity Units - turbidity measurement
Ketones : a family of solvents in which a carbonyl group is bonded to two carbon atoms.
Impingement : the process in which a particle or droplet is removed because inertia moves the particle or droplet in a straight line colliding with the filter fiber or surface to which it becomes attached.
Inches Of Water Gauge : A standard unit used in measuring pressure. 1 in, w.g. = 248.8 Pascals (Pa).
Interception : the process in which a particle or droplet is removed by a filter medium when the particle comes in contact with a fiber and stays attached to it.
"L" type filter : a filter vessel/housing where the inlet and outlet ports are at 90 degrees to each other.
Laminar flow : a non-turbulent flow of a liquid in a pipe with minimal shear forces.
Non-turbulent fluid flow is usually considered laminar if the Reynolds number is less than 2000.
Laminating : the permanent jointing of two or more fabrics, often with an adhesive.
Laser Particle Counter : a device that measures particle size or particle size distribution that measures lazer light reflected by particles.
Latex beads : test beads used in filter efficiency tests.
Log-normal distribution : logarithmic size distributions of aerosols or particles.
Makeup water : water put into a recirculating system to maintain steady purity, temperatures, or additive concentrations.
Machine direction : direction in which a fiber web such as filter media is being produced (long direction of a fabric as opposed to the shorter width).
Manmade fiber : chemically produced fibers that are not completely natural fibers like cotton, wool, flak, silk, etc. They are polymers synthesized from chemical compounds (nylon, polyester), transformed natural polymers (Rayon, acetates) or minerals (glass).
Manifold : manifolds are a combination of ports. In filters, manifolds are inlet or outlet piping that filters or coalescers are fixed to used in place of tube sheets by some vessel fabricators.
Mat : an array or sheet of fibers.
Mean Pore Size : a measurement usually on PMI type equipment of the average pore size in a filter media.
Media migration : fibrous filter media material released into the stream.
Meltblown media : synthetic filter media made from the meltblowing process.
Mercaptans : organic compounds where sulfur and hydrogen (SH) are bonded to the carbon. The hydrogen can ionize and be acidic. Mercaptans have a strong, unpleasant odor.
Mesh : in screens, the number of openings per linear inch.
Meltblown : a non-woven fiber manufacturing process that uses high velocity hot air to tenuate fibers into small fibers. Meltblowing can manufacture flat sheets used in a variety of industries including filtration, or can manufacture tubular filters. Meltblowing is known for producing uniquely fine fibers in comparison to other synthetic fiber production methods.
Meltblown tubular filter : a depth media filter cartridge manufactured either on a continuous process meltblowing onto a spinning mandrill or by rolling meltblown flat sheet.
Micelle : an aggregate of molecules in a colloidal solution, usually in soaps and surfactants.
Microfiberglass Media : filter media made from attenuated glass fibers. Pleated microfiberglass medias are usually wet laid with a binder to hold fibers together.
Microfiltration : filtration of particles between 0.1µm and 3µm, often performed by microfiltration membranes.
Micron : (micrometer) one millionth of a meter. One micron is equivalent to 0.00003937 of one inch. Symbol is µm.
Molecular weight : sum of the atomic weights of the atoms which make up a molecule.
Mono-filament : in filtration, a plastic thread woven into filter screens and filter belts.
Monomers : a small, simple molecules that can be linked together to produce polymers. For example, vinyl chloride is the monomer of poly-vinyl chloride.
µ Mu : Greek symbol for both micro (one-millionth) and for absolute viscosity.
Multi-pass test : a filter element efficiency test method where water or hydraulic oil containing test dust or test beads is re-circulated past the test filter element. Multi-pass tests are used to calculate beta ratios. Contrasts with single-pass test.
Needlefelt : sheet of fibers bound by needling.
Needlepunching : method of binding a web by vertically puncturing it with barbed needles each carrying a tuft of the web's own fibers.
Nominal Filter Rating : filtration industry trade terminology for a measure of retention efficiency, expressed in microns, that signifies a 50-90% retention efficiency.
Nomograph : a graph containing several (usually three) parallel scales graduated for different variables so that when a straight line connects values of any two, the related value may be read directly from the third at a point intersected by the line. Assist in estimating data that normally would require intricate calculations.
Non-woven : a variety of textile fabrics or sheets that are not woven, not paper, and not made into yarns. Non-wovens include spun bonded fabrics, meltblown fabrics, needle punched felts, wet laids, and dry laids.
Nylon Fiber : includes the two principle nylons: NYLON 66 (polyhexamethylene diamine adipamide) and NYLON 6 (polycaprolactam).
Open Area Percent : In cores and screens, the percentage of open space. Open area percent can be an important consideration calculating the pressure drop across an elements and is a critical consideration in the design of separator elements.
Organic : any chemical containing the element carbon.
Orientation : in filter media, the direction in which fibers are lined up.
Outside-in flow : flow through a filter element or coalescing element that flows from outside the element to the inside of the element. There usually is a filter core on the inside to resist collapse from pressure.
Ozone : a gas that is bubbled through water to kill germs that is corrosive to many filter medias.
Ozone Resistance : filter media and filter materials of construction resistance to the oxidizing power of ozone.
Ozonation : use of ozone for water purification.
O/W : nomenclature for an emulsion if the continuous phase is aqueous and the discontinuous phase is a hydrocarbon (oil).
PBT : (polybutylene terephthalate) a polyester resin. The most common form of polyester used in meltblown filter medias.
Particle Filtration : a classification in the filtration spectrum of generally 1µm to 100µm. Usually performed by filter cartridges and bag filters.
Pearlite Mineral : a filter aid.
Peroxone : a combination of peroxide and ozone used to kill germs in water
Permeate : in Crossflow filtration, the fluid that passes through the membrane leaving behind the concentrate.
PET : (polyethylene terephthalate) a polyester formed from ethylene glycol. Fibers from PET can have better chemical and temperature resistance than PBT but PET fibers can be more difficult to meltblow.
pH : the acidity or alkalinity of an aqueous solution. A strong acid give solutions of pH 1-3, weak acids a pH of 6, water has a pH of 7, a weak base has pH of 8, and a strong base give solutions of pH of 12-14. pH measures the concentration of hydrogen ions (excess H+ ions on the acid side and OH- ions on the alkaline side.) pH is a logarithmic scale so the intervals are exponential and represent a much greater difference than the values seem to indicate. For example, an acid with a pH of 1 has ten times the number of H+ ions than an acid with a pH of 2.
-philic : means accepting. Example: oleophilic means oil accepting.
-phobic : means rejecting. Example: oleophobic means oil rejecting. (Phobic=fearing.)
Polyester Fiber : man-made fiber which must be comprised of at least 85% weight of an ester of dihydric alcohol and terephthalic acid. Polyester filter medias come in two forms, PBT and PET.
Polyethylene Fiber : man-made fiber which is Ethylene polymerized at high pressure before being melt spun and cold drawn.
Polypropylene Fiber : man-made Olefin fiber made from polymers or co-polymers of propylene.
Pore : an opening or hole in a filter media.
Porosity : a measure of the ratio of open space to filled space in a porous medium, such as a filter media. Porosity is a measurement relating to dirt holding capacity.
ppm : parts per million, usually by weight.
ppmw : parts per million by weight.
Pressure drop : the differential pressure across a filter housing and elements. Filter elements are changed when pressure drop reaches a pre-determined amount. Also known as static pressure drop.
Produced water : water from oil and gas production.
psi : pounds per square inch. A measure of the static pressure.
psid : pounds per square inch differential. A measure of the differential pressure across a filter element or filter housing.
psig : pounds per square inch gauge.
Rayon : regenerated or "synthetic" cellulose modified to have higher wet and dry strength. Produced by forcing a cellulose solution through spinnerets and solidifying the resulting filaments in an acid-salt coagulating bath.
Reagent : a chemical used to analyze other substances. Purity is essential for reagents.
Residence time : the time a liquid or gas is in contact with an absorbent or adsorbent.
Resistivity : measured in megohm-cm, the measurement of that resistance of a substance to resist the flow of electricity. The inverse of conductivity. Measured by a resistivity monitor in ultrapure water applications.
Reverse flow coalescer : a liquid-liquid coalescer that flows from outside-to-inside.
Reverse osmosis (RO) : membrane separation of dissolved salts. Pressure exceeding the osmotic pressure caused by the dissolved salts is required to effect separation.
Reynold's number : a formula to measure turbulence in liquid flowing in pipe, relating turbulence to pipe diameter, fluid density, fluid viscosity, and fluid velocity.
Roll Goods : sheet fabric or fiber web rolled on tubular core-tubing after being produced.
SAE : Society of Automotive Engineers' specifications for motor oils.
Scrim : Pleat drainage layers. See support layers.
SDI : silt density index.
Sedimentation : gravity separation of solids in water in a settling tank or a clarifier.
Septic : a condition of having bacterial anaerobic growth in water.
Settling velocity : The terminal rate of fall of a particle or droplet through a fluid as induced by gravity or other external force.
Settling tank : a gravity filter.
Settling zone : in a coalescer vessel or a gravity separator, the length of the vessel where droplets fall.
Single-pass test : a filter element efficiency test method where water or hydraulic oil containing test dust or test beads is pumped past the test filter element and not recirculated. Multi-pass tests are usually used to calculate "clean" or 'first pass" efficiency ratings and may not take into account the effect of filter cake on increasing the efficiency of the filter media over the life of the filter. Contrasts with single-pass test.
Sintering : welding together of metal or plastic powders or fibers at temperatures just below the melting or fusion point.
Sodium hydroxide : caustic soda. NaOH.
Sodium hypochlorite : bleach. Na(OCl)2.
Specific gravity : the ratio of the density of a liquid to the density of water at the same temperature. The specific gravity of water at 60° F is 1.00.
Specific volume : volume of weight of a substance usually expressed in gallons per pound.
Spent caustic : waste from caustic treatment.
Spinning : process by which fibers or filaments are drawn out and spun together to produce a thread.
Spinneret : device used for making rayon, nylon, and other synthetic fibers. It consists of a plate pierced with holes through which plastic material is extruded in filaments.
Spunbond : 1) in filter media, a generic term for non-woven webs made from a continuous mat of randomly laid filaments. The filaments are bonded together by heat and pressure or needlepunching. In filtration, tubular depth filters made with polymeric fiber that is extruded through Spinnerets to form fibers, usually a meltblown tubular filter.
Sock : in filtration, a tubular fabric that is woven to stretch often used as a sizing layer for coalescer elements.
Sock filter : a nominal natural gas filter made cellulosic material and a cotton sock.
Solubility : the tendency of one substance and another to blend together on a molecular level.
Solution : a uniform mixture at the molecular level of two of more substances. A substance in solution cannot be separated by mechanical means such as filtration or coalescing.
Standard atmospheric pressure : 14.696 pounds.
Stokes Law : a formula describing the rate at which a sphere will rise or fall in a liquid. The rate at which spheres rise or fall varies on the square of it's radius and varies depending on the density of the sphere and the density and viscosity of the liquid.
Sweetening : Petrochemical plants, refineries, and gas processing facilities treat natural gas, natural gas liquids, crude oil, and fuels to remove acidic sulfur compounds such as hydrogen sulfide (H2S) and mercaptans. These processes are called sweetening. Sweetening can be performed by physical absorption with a solvent such as Selexol, by physical adsorption with molecular sieves such as zeolites, and by chemical absorption with a basic solution such as amines or caustics. Chemical absorption is the most common process used to absorb large quantities of H2S and mercaptans.
Sterilizing Filter : in pharmaceutical filtration, a membrane filter that, when challenged with the microorganisms Brevundimonas diminuta, at a minimum concentration of 107 organisms per square centimeter of filter surface, produces a sterile effluent.
Sulfides : salts or other derivatives of hydrogen sulfide.
Support Layers : layers of open filter media pleated with a tighter filter media to provide structural support and drainage. Common drainage layers are made of non-woven materials, cellulose medias, and screens. Also known as scrim.
Surface area : the effective filtration area of a pleated filter cartridge calculated as:
(Pleat height in inches x 2) (number of pleats) (width of the filter media in inches) / 144.
Surfactants (surface active agents) are substances in your product which can disarm (render ineffective) coalescer elements.
Suspended solids : Particles in water that can be removed by sedimentation or filtration.
Synthetic fibers : man made fibers made of thermoplastics including polypropylene, polyester, and nylon.
Thermoplastic : A material capable of being repeatedly softened. Most synthetic cartridge filter medias are thermoplastic.
Thermoset : A material, such as PTFE or an epoxy resin, which undergoes a chemical reaction by the action of heat, catalyst, ultraviolet light, etc., to become a relatively insoluble and infusible substance that will then decompose rather than melt.
Titration : a method for determining the amount of a substance by adding a reactive substance.
Total Dissolved Solids (TDS) : the weight of solids in solution measured by drying filtrate.
TOC : total organic carbon.
Total Suspended Solids (TSS) : the weight of solids in a liquid sample of a known volume, often measured by filtering a volume of liquid through a membrane and weighing dried solids.
Total Suspended Particulate (TSP): the total liquid and solid contaminant content usually in a gas or in gas emissions.
Trickling filter : aerobic bed filter used to treat waste water.
Tube Sheet : a metal plate in a filter vessel that separates the unfiltered stream from the filtered stream. In cartridge filtration systems, the filter elements (bags or cartridges) are supported by the tube sheet and are sealed to holes through the tube sheet.
Turbidity : a measure of the amount light is blocked by suspended solids in a clear liquid, usually water.
Turbulent flow : flow of a liquid in a pipe in which the fluid moves in a random manner due to friction, velocity, and viscosity, with a Reynolds number usually greater than 4000.
µ Mu : Greek symbol for both micro (one-millionth) and for absolute viscosity. A micrometer is µm. Absolute viscosity is measured in centipoise.
Ultrafiltration : membrane filtration up to 0.1µm.
Ultrapure water : Highly purified water of high resistivity and no organics; usually used in the semiconductor and pharmaceutical industries. Industrial grade filters are often not compatible with ultrapure water because of the aggressive solvent nature of the water and the tendency of the water to become septic.
Unloading : the release of particulate that had been captured by the filter media. Revealed by a reduction in differential pressure. In depth filters this is the result of a sponging action in the filter element.
Ultrasonic Bonding : in filtration, process of using high-frequency sound to vibrate thermoplastic fibers, generate heat and cause them to bond together. Used to sideseam pleated synthetic filter cartridges.
USP-purified water : water purified by distillation, ion exchange or other suitable process that complies with US EPA drinking water regulations.
Vacuum : the depression of pressure below the atmospheric pressure, usually expressed in inches of mercury.
Viscosity : the thickness of a liquid, a measurement of the resistance to flow of a liquid. Commonly measured in centipoise (cP), kinematic viscosity, centistokes, and saybolt universal seconds (SUS).
Volatile organic compounds (VOCs) : highly evaporative hydrocarbon compounds, except ethane and methane.
Web : in textiles and non-wovens, a mat or sheet of fibers.
Weir : a baffle.
Wet Laying : forming a web using modified papermaking techniques - basically using a liquid dispersion method of laying fibers onto a moving screen.
Wetlaid : fiber web made by Wet Laying.
Wire Diameter : In screens, the thickness of the wire in inches.
Wetting : in filtration, the adsorption of a liquid on a filter medium. The opposite of repelling. Wettability is elated to surface tension. Some -phobic materials must be "wetted out" with a wetting agent before use as a filter medium, for example a tight polypropylene media may have to be soaked in isopropyl alcohol before use a water filter media.
W/O : nomenclature for an emulsion if the continuous phase is an organic liquid (an 'oil') and the discontinuous phase is aqueous.
Sources :
IUPAC Compendium of Chemical Terminology 2nd Edition (1997)
Hawley's Condensed Chemical Dictionary, 13th addition (1997)
Ahlstrom Corporation "Glossary" online at:
http://www.ahlstrom.com/ahlstrom/glossary/glossary_home.htm
International Society for Pharmaceutical Engineering "Glossary of Applied Industry Terms" Author Michelle M. González online at:
http://www.ispe.org/Glossary/gloss-a.htm