Glossary of Filtration terms
ABRASION: Migration of foreign material which enters the fluid stream from system components that wears from close tolerances, vibration or shock.
ABRASIVE: Any solid material such as grit with erosive properties.
ABRASIVES: Hard-structured strong solid.
ABSOLUTE: An arbitrary term used to describe a degree of filtration. The filtration industry uses various methods of determining absolute ratings which are not necessarily interchangeable. Generally absolute refers to 100% removal of solids above a specified micron rating on a single pass basis.
ABSOLUTE: The sum of gauge pressure and atmospheric pressure.
ABSORB: To take up by cohesive, chemical or molecular action.
ABSORBENT: A filter medium that holds contaminants by mechanical means. Here one substance soaks completely through another, sometimes by undergoing a chemical change.
ACIDITY: The quality, state or degree being acid. In lubricating oils, acidity denotes the presence of acid-type constituents whose concentration is usually defined in terms of a neutralization number. The constituents vary in nature and may or may not markedly influence the behaviour of the fluid.
ADDITIVE: A chemical material usually added to a product to impart new or unusual characteristics or to improve existing characteristics.
ADSORB: To take up by adhesion of molecules of gases or dissolved substances to the surface of solid bodies resulting in high concentration of the gas or solution at the place of contact. Gas or solution is condensed on the surface of the adsorbent, while during adsorption the material absorbed penetrates throughout the mass of the absorbent.
ADSORBATE: The material which is adsorbed i.e. the gas, vapor or liquid which adheres or is chemically attracted to the surface of the solid.
ADSORBENT: A material which adsorbs i.e. the solid which attracts and holds on its surface the gas, vapor or liquid components. Also, the materials added to liquors to decolonize or purify by adsorbing the colour or impure fuller’s earth, activated carbon, activate alumina, etc. which are all adsorbents.
ADSORBENT: A filter medium primarily intended to hold soluble and insoluble contaminants on its surface by molecular adhesion.
ADSORPTION: The natural phenomenon of a gas, vapor or liquid being attracted to and held on the surface of a solid. To some extent adsorption takes place on any solid surface but certain materials have sufficient adsorbent capacity because of the finely divided material to make them useful in such industrial applications such as the purification and separation of gases and liquids.
AGGLOMERATE: A group of two or more particles combined, joined or clustered by any means.
AGGREGATE: A relatively stable assembly of dry particles formed under the influence of physical forces.
ASME: American Society of Mechanical Engineers.
ASPHALTINE: Product of Partial Oxidation of Oil.
ATMOSPHERIC PRESSURE: The force exerted on a unit area by the weight of the atmosphere.
ATOM: Smallest particle of an element which retains properties of the element Example: Carbon atom.
AUTOCLAVE: Sterilizing apparatus which uses steam at high pressure.
BACK PRESSURE: In filter use, resistance offered by filter, usually measured in PSI.
BACKWASH: To clean a filter element by reversing the direction of flow through it.
BASKET STRAINER: Vessel for the removal of coarse bulk solids from liquid, air, or gas; the element is a basket covered with a screen of a given mesh.
BED (CAKE): Mass of impurities that forms on a filter element.
BETA RATIO: An accurate indication of how the filter performs throughout the life of a filter. The BETA RATIO is an average filtration rating.
BLEEDER: A system in which part of the fluid from the main flow is diverted.
BLOTTER TEST: A visible means of checking oil clarity; one drop on a blotter will concentrate dirt or foreign matter in the centre of the ring.
BLOWBACK: To reverse flow of the air, steam, or fluid through the media to effect solids removal, sometimes referred to as backwash.
BRIDGING: A condition of filter element loading in which contaminant spans the space between adjacent sections of a filter element thus blocking a portion of the useful filtration area.
BUNA N: Gasket material, a synthetic rubber frequently used for vessel closures, Flanges, and filter elements.
BURST: An outward structural failure of the filter element caused by excessive differential pressure.
BY-PASS: Condition resulting from the product flowing through a vessel other than through the media. Also, a filtering system which filters only part of the steam on a continuous basis.
BY-PASS INSTALLATION: A system where part of the main flow is diverted to pass through a filter.
BY-PASS VALVE: Valve to pass the flow around the media or the vessel. Usually activated at a given differential pressure setting.
CAKE: Solids deposited on the filter medium during filtration in sufficient thickness that needs to be removed in sheets of sizable pieces. In many cases, cake may provide its own filter media by adding to the surface of media. Also referred to as discharged solids or residue.
CANISTER: Container or mounting mechanism for elements.
CAPACITY: Volume of product which a vessel will accommodate. This is 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.
CARTRIDGE: Removal medium used in a vessel to perform the function of coalescing, filtering, or separating. Also referred to as element, media, repack, etc.made in a specified physical shape to be mounted by use of hardware designed for that purpose.
CARTRIDGE: The Porous device, usually fitting in a filter housing, which performs the actual process of filtration.
CENTER PIPE: Component of a vessel which is used as a mount for cartridges made with perforated effect to accommodate flow. A center rod is used for the same purpose but is not perforated and does not accommodate flow.
CENTER-ROD: Components of a vessel used for mounting cartridges in the vessel. Usually made of a round bar material. A center pipe can also be used for the same purpose but is made with perforated effect and directs flow through the cartridge.
CENTER SEAL: Part which forms seal between two elements when one element is on the top of another element, can also be called an adaptor.
CENTER TUBE: Component of an element or cartridge which supports the media at the center or at the smallest diameter.
CENTIPOISE: One-hundredth of a poise. A poise is the unit of viscosity expressed as one dyne per second per square centimetre.
CENTISTOKE: It refers to one-hundredth of a stoke. A stoke is equal to the viscosity in poises times the density of the fluid in grams per cubic centimetre.
CHANNEL: To cut grooves or lines in or through the solids deposited on the media, or through the media itself. Also, may be described as a breakthrough in the media which would result in a by-pass.
CLEANER BLADES: Stationary blades located between stacked discs of a metallic self-cleaning filter cartridge to comb out dirt particles as the cartridge is rotated.
CLOUD POINT: Temperature of a petroleum oil which paraffin, wax or other solid substances begin to crystallize out or separate from solution when the oil is chilled under definite prescribed conditions.
COAGULANT: That which produces agglomeration of suspended solids.
COALESCER: A mechanical device which united discrete droplets of one phase prior to being separated from a second phase. Can be accomplished only when both phases are immiscible. Requires a tight media which is preferentially wettable and, by its nature of being tight, the media is also a good filtering material. Good coalescing permits gravity separation of the discontinuous phase. Coalescing may be accomplished by only a coalescer cartridge when the specific gravities of the two phases are widely separated. As the gravities difference become less, the two stage principle is generally required where finely coalesced discontinuous droplets are repelled by the second stage separator cartridge.
COALESCING: The action of uniting of small droplets of one liquid preparatory to its being separated from another liquid.
COLLAPSE PRESSURE: The pressure impressed across a filter element (cartridge). Sufficient to cause collapse of the element.
COMBINATION: A filter medium composed of two or more types, grade or arrangements of filter media to provide proportion which are not available in a single filter medium.
CONTAMINANT: Anything in the fluid that should not be there.
CONTAMINATE: The foreign matter in a fluid which is accumulated from various sources such as system dirt, residue from wear of moving parts, atmospheric solids which settle in an open system contaminates tend to discolor a liquid, cause additional wear on moving parts, cause system upsets in process stream, or reduce the efficiency of a fluid. Water as well as solid may be considered a contaminate when the presence of water causes adverse results. The presence of contaminates, whether liquid or solid, is the basis on which the use of filters or separator or/filters are sought.
CORE: Material used for the center of an element, generally of the wound design. May also be called a center tube when used in the coalescer, separator, or other type filter element.
CORROSION: The conversion of metals into oxides, hydrated oxides, carbonates, or other compounds due to action of air or water, or both. Salts and sulphur are also important sources of corrosion. Removal of solids and water reduces the effect or speed of corrosion in many cases; and in other cases, corrosion inhibitors are used to reduce the effect of corrosion.
CP: A section of less dense material in the media which allows a cold liquid to flow through the element controlling pressure drop below bypass opening.
DEGRADATION: Wearing down, or reduction in the efficiency of a media.
DEGREE OF FILTRATION: Fineness of a filter medium-size of the smallest particles filtered out.
DELTA “P”: A symbol (P) designating pressure drop. The difference in pressure between two points, generally measured at the inlet and outlet of a filter, separator/ filter, etc. Normally measured in pounds per square inch (psi), inches of mercury (In Hg), or inches of water (In H2o).
DENSITY: The weight per unit volume of a substance (specific weight).
DEPTH: A filter medium which primarily retains contaminants within the tortuous passages within the thickness of the element wall.
DEPTH TYPE FILTRATION: Filtration accomplished by flowing a fluid through a mass filter media providing a tortuous path with many entrapments to stop the contaminates. Flow may be cross-flow such as from the outside to inside and then down the center of an element, or from end to end. Certain types of solids, or combinations of solids, do not lend to surface filtration and depth type filtration is found to be more suitable.
DETERGENT OILS: Lubricating oils possessing special sludge dispersing properties commonly used in internal combustion engines. These properties are incorporated in the oil using special additives.
DIELECTRIC: A substance which will not conduct electricity.
DIFFERENTIAL PRESSURE: The difference in pressure between two given points of a filter, separator/ filter, etc.
DILATANT: A flow condition where certain liquids will show an increase in viscosity as the rate of shear or flow volume is increased.
DIRT HOLDING PRESSURE: The volume of contaminate an element can hold before reaching the maximum allowable pressure drop. Volume will vary depending on the size and design of the element and the density of the solid particles. Usually reported by weight such as grams or pounds per element. Also called solids retention or solids holding capacity.
DISCHARGE: Flow rate through a filter.
DISPOSABLE: Describes element which is to be discarded after use and replaced with an identical element. Same as replaceable. Opposite of reusable.
DUAL DENSITY: A depth element that is constructed of two different medias. Not blended into a homogeneous mixture but remaining as two different distinctive medias.
DROP: The quantity of fluid which falls into one spherical mass; a liquid globule. May also be described as several to many droplets.
DROPLET: A minute drop which mates to form larger drops capable of falling by gravity.
EDGE FILTER: Filter using shearing edges to separate solids from a liquid by shearing the oil film surrounding the particles.
EDGE TYPE: Applies to liquid filters constructed of metal or paper discs, or specially constructed wire wound cylinders; contaminants are entrapped at the edges of the medium. Generally used to remove small quantities of very fine particles. Some have knife or blade cleaners to remove the accumulated solids.
EFFECTIVE AREA:The area of a medium that is exposed to flow and usable for its intended purpose coalescing, filtering, or separating. Opposite of blind spots or dead area.
EFFECTIVE OPEN AREA: Area of the filtering medium through which the fluid may flow.
EFFICIENCY: Degree to which element will perform in removing solids and/ or liquids. Output divided by input.
ELEMENT: Medium used in vessel to perform the function of coalescing, filtering, or separating. Also referred to as a cartridge, repack, etc. The porous device which performs the actual process of filtration.
ELEMENT BY-PASS VALVE: A valve within a filter to limit the differential pressure which can be impressed across the filter element.
EMULSIFICATION: A dispersion of one substance in the form of minute drops within another substance.
EMULSION: A dispersion of fine liquid particles in a liquid stream which do not necessarily dissolve in each other but are held in suspension. Many emulsions may be broken by coalescing if the liquids are immiscible. Emulsion stabilizers modify the surface tension of the droplets which makes coalescing difficult, if not impossible.
ENTRAINED WATER: Discrete ware droplets carried by a continuous liquid or gas phase when water is immiscible with the liquid. It can be separated from the continuous phase by coalescing and gravity separation. Usually picked up in a system by condensation or a water washing used in process.
ENTRAINMENT: Mist, fog, or droplets of a liquid which is usually considered to be a contaminate when used in the filtration industry.
EXTENDED AREA: Principal of shaping the element to give it more effective area than a simple cylinder of the same size.
FELTED ELEMENT: Constructed by random layers of fibre, usually strengthened by a resin binder.
FIBER: Flexible material with two relatively small dimensions and one long dimension.
FILTER: A term generally applied to a device used to remove solid contaminate from a liquid or gas, or separate one liquid from another liquid or gas. A filter, as referred to in the industry today, is a device which removes contaminates. If a device is used to remove solids and liquids contaminates, it is referred to in general terms as a separator, separator/filter, or entrainment separator. A filter may be one of several such types as replaceable cartridge, cyclone, edge, leaf, baffle, plated, framed, percolated, and centrifuge. The term filter is sometimes erroneously used to describe the media used inside the vessel or filter case, but the correct use should be filter element, cartridge, etc
FILTER/COALESCER: Single stage vessel for coalescing and separating one immiscible fluid from one another and the removal of solids. Generally recommended for use where continuous phase has light gravity. Available with various efficiencies.
FILTER EFFICIENCY: Expressed as a percent of contaminant introduced to the system, it is the ability of a filter to remove specified contaminants at a given contaminant concentration under specified test condition.
FILTER ELEMENT LIFE: Span of operation from clean unit to a predetermined pressure drop build-up, usually measured in lapsed time.
FILTER LIFE: Span of operation from start to complete plugging usually measured in hours of operation.
FILTER MEDIUM: The porous material mounted on a plate or frame which separates the solids from the liquid in filtering. Also referred to as filter cloth, filter plate, or septum. The material that performs the actual process of filtration.
FILTRATE: Filtered fluid which flows out of a filter.
FILTRATION RATING, ABSOLUTE: The diameter of the largest hard spherical particle that will pass through a filter under specified test conditions. This is an indication of the largest opening in the filter medium.
FILTRATION RATING, MEAN: A measurement of the average size of the pores of the filter medium.
FILTRATION RATING, NOMINAL MICRON: An arbitrary micron value indicated by the manufacturer. Often defined 95% of all the particles of this size, and larger, retained by the filter medium.
KARL FISCHER: Analytical method of determining amount of water present in a sample by filtration.
FLOW CHARACTERISTICS: The nature of fluid movement as being turbulent, laminar, constant or variable rate to various degrees.
FLOW RATE: The rate at which a product is passed through a vessel or system, generally expressed as gallons per minute, barrels per hour, barrels per day, actual or standard cubic feet per minute, hour, day, etc.
FLUID: A liquid or gas which can be filtered by passing through a filter.
FREE WATER: Water entrained in a lubricating oil or fuel forming two distinct phases with the fluid and with a tendency to separate as a result of the differences in densities.
FULL FLOW: Product flow through the vessel at the rate for which the vessel is designed to operate. Also refers to all products passing through a medium. The opposite of a by-pass filter which is designed to filter only a portion of the stream on a continuous basis.
FULL FLOW FILTRATION: System which provides for filtering all the fluids which is pumped to or from wear surfaces or work stations each pass.
GAGE PRESSURE: All pressure greater than atmospheric pressure as read on a pressure gauge.
GAS SCRUBBER: A vessel designed to remove liquid and solid contaminates by impingement on a series of baffles or demister pads. Accomplished by drastic reduction of velocity as the gas enters the scrubber. Recent advances made in entrainment separation would expand the general use of the term to include mechanical cartridge type separators.
GEL: A semi-solid susceptible to pressure deformation. Has habit of sticking to surfaces.
GRADUAL DENSITY: A media of different densities. One media of a dense type packed around the center tube with a media of less density around outside. Both medias are tapered at opposite directions. This allows high flow through the less dense media. It’s similar to the CP element in performance.
GRAM LIFE: Grams weight of contaminant introduced to a filter element at controlled rate to a determined differential pressure.X
GRAVIMETRIC EFFICIENCY: Measure of efficiency in terms of weight.
HOLDING CAPACITY: In general usage refers to the amount of solids, particulates or foreign materials.One or more elements is capable of retaining up to the terminal or maximum differential pressure. Also, it may refer to volumetric holding capacity of either a solid or a liquid.
HOUSING: Container for a filter element (s).
HYDRAULIC FILTER, DUAL: A hydraulic filter having two filter elements in parallel.
HYDRAULIC FILTER, DUPLEX: An assembly of two hydraulic filters with valving for selection of either or both filters.
HYDRAULIC FILTER, FULL FLOW: A hydraulic filter, which under specified conditions filters all influent flow.
HYRAULIC FILTER, TWO STAGE: A hydraulic filter having two filter elements in series.
HYDRAULICS: The study of fluids at rest or in motion.
HYDROPHILIC: Water accepting or water wetting. Having an affinity for water, Capable of uniting with or dissolving in water. Effective coalescing requires a media to have hydrophilic characteristics that causes free or entrained water to commingle into droplets which, when mated with other droplets, form drops separated by gravity. It’s opposite of hydrophobic.
HYDROPHOBIC: Non-water wetting. Having an antagonism for water. Not capable of uniting or mixing with water. Hydrophobic features are induced in the process of cellulose manufacture. Opposite of hydrophilic.
HYDROSTATIC TEST: A test conducted with either air, water, or other fluids at a given value over design pressure, to prove the structural integrity of a pressure vessel.
IMMISCIBLE: Incapable of being mixed; insoluble; opposite of miscible.
IMPREGNATION: Process of treating a coarse filter medium with resins.
IMPURITY: See “contaminant”- any undesirable material in the fluid.
INDICATOR, BY- PASS: An indicator which signals alternate flow.
INDICATOR DIFFERENTIAL PRESSURE: An indicator which signals the difference in pressure at two points.
INITIAL PRESSURE DROP: Loss in differential pressure between two points upon the start of flow through a vessel using new elements.
IN-LINE: Describes inlet and outlet connections which are positioned at the same height on opposite sides of a vessel so that an imaginary straight line can be drawn connecting one to the other. Also describes a small filtration unit that fits into a line and forms a similar image to the line, as in the case of a hose.
INSOLUBLE: Incapable of being dissolved in a fluid; opposite of soluble.
INTERFACE: Surface over which continuous phase and discontinuous phase are in contact.
IMPINGEMENT: The direct high velocity impact of the fluid flow upon or against an internal portion of the filter.
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KEROSENE: A petroleum liquid used as a fuel for commercial jet powered aircrafts, and/or for heating purposes.
KNIFE EDGE PLEATS: The sharply defined creases at the outer edge of a pleated element.
LACQUER: A natural or synthetic resin which is dissolved in a suitable solvent such as hydrocarbon oil rich in aromatics. When applied, the oil solvent evaporates, leaving behind a lacquer film.
LINE SIZE: The size of line used to carry the product in a system, such as a six-inch line.
LUBRICATION: Substituting fluid friction for solid friction by inserting oil between two moving parts.
MAGNETIC SEPARATOR: A separator that uses a magnetic field to attract and hold ferro magnetic particles.
MATRIX: The structural support yarn or twine in wound elements is usually wound in a diamond.
MAXIMUM DIFFERENTIAL PRESURE: The highest-pressure differential which an element is required to withstand without any sort of structural failure or collapse.
MAXIMUM OPERATING PRESSURE: The maximum pressure allowed in a system.
MEDIA: Plural of medium material of which elements are made.
MEDIA (MEDIUM): A porous or slotted mass in a filter element to separate solids from a fluid by difference in size of openings and contaminants.
MEDIA MIGRATION: Carry-over of fibers from filter, separator elements, or other filter material into the effluent. Less definitive than fiber migration and is quantitative in natrure.
MEDIUM: The principle component of an element. A material of controlled pore size or mass through which a product is passed to remove foreign particles held in suspension or to repel droplets of coalesced water, or material without controlled pore size such as glass fiber mats. They contribute to filtration, coalescence, or separation of two immiscible liquids.
MEMBRANE: In filtration, the term membrane is used to describe the media through which the liquid stream is to be passed or exchanged. Membranes are normally associated with ion exchanged media such as dialysis, osmosis, diffusion, etc. although filter paper itself could be classed as a membrane.
MERCAPTANS: Unsaturated sulphurs..
MICRON: A short unit of length in the metric system. One millionth of a meter, 10-4 centimeter, 10-3 millimeter, or 0.000039 of one inch. Used as a cotenon to evaluate the performance or efficiency of a filter media or to describe the condition of a filter media or to describe the condition of either the influent or effluent. Usually stated in terms of being either absolute or nominal. Nominal micron rating is generally taken to mean that 98% of all articles over a given micron value have been removed by a specific media or medium. Absolute micron rating is generally taken to mean that all particles over a given micron value have been removed. The naked eye can see a particle 40 microns or larger.
MIGRATION: Contaminant or media released to pass downstream from filter element.
MMSCFD: Million Standard Cubic Feet per Day.
MMSCFH: Million Standard Cubic Feet per Hour.
MMSCFM: Million Standard Cubic Feet per Minute.
MODULAR: A filter element which has no separate housing of its own but whose housing is incorporated into the equipment which it services. It may also incorporate a suitable enclosure for the filter cavity..
NEWTONIAN: A liquid which does not change in viscosity with a change in rate of shear, agitation or flow rate..
NPT: National Pipe Thread Standard.
NTP: Normal conditions of temperature and pressure. Whenever this term is used it refers to a gas measured at pressure one atmosphere absolute (760 mm of Hg) and a temperature of •C. However, some sources use a different reference temperature to define NTP.
OPEN AREA RATIO: The ratio of pore area of a filter medium expressed as a percent of total area.
OPERATING PRESSURE: The normal pressure at which a system operates.
OPERATING PRESSURE CRITICAL: Pressure above the normal or design limits which may cause damage or rupture.
OPERATING PRESSURE, MAXIMUM: The maximum pressure allowed in the system.
OUTER SHELL: Outer covering of element, usually perforated or screened.
OUTER WRAP: Outside covering of an element.
OUTSIDE IN: Flow of product from outside to inside of an element.
PAPER: Medium used in many elements. A very general term applied to resin impregnated cellulose. Many types of paper or cellulose are used as filter media made to specifications.
PARTIAL FLOW: See “By-pass installation” a system that diverts part of the main flow and passes it through a filter.
PARTICLE COUNT: A practice of counting particles of solid matter in groups based on relative size. Frequently used in engineering, a filter to a specific task or to evaluate the performance of a filter under specific operating conditions. When used as data to engineer a filter, proper consideration can be given to the type of media to be used, expectant life of the media and the true cost of operation.
PARTICLE SIZE DISTRIBUTION: A tabulation resulting from a particle count of solids grouped by specified micron sizes to determine the condition of either the influent or effluent stream. Usually expressed in percentage of total solids to the specific group. Example: 31% in the 6 to 10-micron group/ See particle count.
PERCENT FREE AREA: Quantitatively proportion of an element’s surface area.
PLAIN: A filter element whose medium is not pleated or otherwise extended and has the geometric shape of a cylinder, cone, disc, plate, etc.
PLEATED: A filter element whose medium consists of a series of uniform folds and has the geometric shape of a cylinder, cone, disc, plate, etc.
PLASTISOL: A suspension of thermosetting plastic which can be moulded into any desired shape. Used as a combination end cap and gasket on element.
PLUGGED: Condition of a filter when it has collected its full capacity of contaminants and will not pass any more fluid.
POROSITY: The ratio of void volume to total cake volume. Also describes filter media which may have larger pores than other media.
POUR POINT: The lowest temperature at which a liquid will pour or flow without disturbance under specified conditions.
PRECOAT: A filter medium in loose powdered form, such as Fuller’s or Diatomaceous earth, introduced into the upstream fluid to condition a filter element.
PREFILTER: Filter for removing gross contaminate before the product stream enters a separator/filter.
PRESSURE: The force exerted per unit area by a fluid.
PRESSURE ABSOLUTE: Gauge pressure plus 14.7 psi.
PRESSURE ATMOSPHERIC: The force exerted by the atmosphere at sea level which is equivalent to 14.7 psi.
PRESSURE DIFFERENTIAL: The difference in pressure between two points.
PRESSURE DROP: The difference in pressure between two points, generally at the inlet and outlet of a filter or a separator/filter. Measured in pounds per square inch gage, or inches of mercury.
PRESSURE RATING, OPERATING: The normal pressure at which a filter housing can operate at specified operating conditions.
PRESSURE RELIEFValve which permits enough liquid or gas to escape from the vessel to prevent extreme pressure build up within the vessel. PSI: Pounds per square inch. PSIA: Pounds per Square Inch Absolute. PSID: Pounds per Square Inch Differential. PSIG: Pounds per Square Inch Gage.
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RATE OF FLOW: The rate at which a product is passed through a vessel or system, generally expressed as gallons per minute, barrels per hour, barrels per day, actual or standard cubic feet per minute, hour, day, etc. Same as flow rate.
RATED FLOW: Normal operating flow rate at which a product is passed through a vessel flow rate thatthe vessel and/or media are designed to accommodate.
REPLACEBALE: Describes element which is to be removed after use and replaced with an identical element.
REPLACEMENT ELEMENT: An element or a cartridge used to replace a disposable which has been loaded to its capacity with (cartridge) contaminants.
REUSABLE: Describes element which may be cleaned and used again. Opposite of disposable or replaceable.
SAE: Society of Automotive Engineers.
SAE NUMBER: A classification of lubricating oils for crankcase and transmissions in terms of viscosity as standardized by the Society of Automotive Engineers.
SAYBOLD SECONDS UNIVERSAL (SSU): Units of viscosity as measured by observing the time in seconds required for 60ml of a fluid to drain through a tabular orifice that measures, 0.483 inches long by 0.0695 inches in diameter at stated conditions of temperature and pressure.
SCFD: Standard Cubic Feet per Day.
SCFH: Standard Cubic Feet per Hour.
SCFM: Standard Cubic Feet per Minute.
SELF CLEANING: A filter element designed to be cleaned without removing it from the filter assembly or interrupting flow.
SEPARATION: The action of separating solids or liquids from fluids. May be accomplished by impingement, filtration, or by coalescing. The term “separation” is used in some circles when referring to the separation of liquids. Also used to describe the action in the second stage of two-stage separation.
SEPARATOR: A device whose primary function is to isolate contaminants by physical properties other than size.
SEPARATOR/FILTER: Vessel which removes solids and entrained liquids from another liquid or gas. Uses some combination of a baffle and/or coalesce filter or separator element. May be single stage, two stage or single or two stage with prefilter section for gross solids removal. Common applications are the removal of water from gas or another immiscible liquid. General reference to term applies that the equipment is capable of both separation and filtration to specific degrees of efficiencies.
SERVICE LIFE: The length of time an element operates before reaching the maximum allowable pressure drop.
SHELL: Outer wall of a vessel. Also referred to as body.
SHUNT INSTALLATION: A system with a filter paralleled by a metering device both in the main supply line.
SINTERED: Media, usually metallic, processed to cause diffusion bonds at all contact points, retaining openings the passage of filtrate.
SKID MOUNTED: Describes one or more vessels with pump and motor, all mounted on a portable platform.
SLOT AREA: Sum of the area of all the fluid path openings in a metal-edge filter element.
SLUDGE: Dirt, carbon, water and chemical compounds as found in oils.
SOLID SUSPENSION: A mixture of solids suspended in a fluid.
SOLIDS: A mass or matter contained in a stream which is considered undesirable and should be removed.
SOLUTION: A single phase combination of liquid and non-liquid substances which are two or more than two more liquids.
SPACING: The distance between adjacent surfaces or stacked discs, edge wound ribbons or single layer filaments. This dimension determines the smallest dimension of solid particles to be retained.
SPECIFIC GRAVITY: Ratio of substance’s weight to that of some standard substance (Water for liquids and solids, air or hydrogen for gases ).
SURFACE: A filter medium which primarily retains contaminant on the influent face.
SURFACE AREA: Total area of an element that is exposed to approaching flow.
SURFACTANTS: Coined expression for surface active agents which are sometimes called emulsifiers or wetting agents. First appeared in hydrocarbons with the advent of the catalytic cracking process in refining. Caused by the forming of sodium sulfonate and sodium naphthenate molecules. Affects liquid/liquid separation by reducing interfacial tension and forming into a slime which binds off the fibers used in coalescing media.
SURGE: The peak system pressure rise measured as a function of restricting or blocking fluid flow.
SUSPENSION: Solids or liquids held in other liquids.
SUSPENDED SOLIDS: Non-settled particles in fluid.
SWING BOLT: A type of vessel closure which reduces service time. Opposite of thru-bolt flange where studs and nuts are used such as with ASA type flanges.
THIXOTROPIC: A liquid which shows a marked reduction in viscosity as the rate of shear, agitation or the flow rate is increased.
TORTUOSITY: The ratio of the average effective flow path length to minimum theoretical flow path length (thickness) of a filter medium.
TURBID METRIC EFFICIENCY: Filter inlet turbidity – Outlet turbidity/by inlet turbidity.
TURBIDITY: Stirred up sediment or contaminant in a fluid.
TURN-OVER: Number of times the contents of the system pass through a filter per unit time.
ULTRAFILTER: Membrane type to remove very fine suspended submicronic particles as well as some dissolved solids.
UNLOADING: Release downstream of trapped contaminate, due to change in flow rate, mechanical shock and vibration or as excessive pressure builds up or media failure.
VACUUM: Reference to pressure below atmospheric pressure.
VISCOSITY: Degree of fluidity, property of fluid’s molecular structure by virtue of which they resist flow. The resistance of flow exhibited by a liquid resulting from the combined effects of cohesion and adhesion. The units of measurement are the poise and the stoke. A liquid has a viscosity of one poise if a force of one dyne per square centimeter causes two parallel liquid surfaces one square centimeter in area and one centimeter apart to move past one another at a rate of one centimeter per second. There are a great many crude and empirical methods for measuring viscosity which generally involves measurement for the time of flow or movement of a ball, ring or other object in a specially shaped or sized apparatus.
The internal molecular friction of a liquid or that property which resists any force tending to produce flow.
WOUND: A filter medium comprised of two or more layers of helical wraps of a continuous strand or filament in a predetermined pattern.
WOVEN: A filter medium made from strands of fiber, thread or wire interlaced into a cloth on a loom.
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