A.G.M.A. Abbreviation for "American Gear Manufacturers Associations," an organization serving the gear industry.
A.S.T.M. = American Society for Testing Materials A society for developing standards for materials and test methods.
Abel tester A closed-cup flash tester for kerosene and other oils
Abrasive wear (or cutting wear) comes about when hard surface asperities or hard particles that have embedded themselves into a soft surface and plough grooves into the opposing harder surface, e.g., a journal.
Absolute filtration rating 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 elements.
Absolute pressure Total pressure equal to gauge pressure plus 14.7 lbs./sq. in at sea level
Absolute viscosity A term used interchangeably with viscosity to distinguish it from either kinematic viscosity or commercial viscosity. Absolute viscosity is the ratio of shear stress to shear rate. It is a fluid's internal resistance to flow. The common unit of absolute viscosity is the poise. Absolute viscosity divided by fluid density equals kinematic viscosity. It is occasionally referred to as dynamic viscosity. Absolute viscosity and kinematic viscosity are expressed in fundamental units. Commercial viscosity such as Saybolt viscosity is expressed in arbitrary units of time, usually seconds.
Absorbent filter A filter medium that holds contaminant by mechanical means.
Absorption The assimilation of one material into another; in petroleum refining, the use of an absorptive liquid to selectively remove components from a process stream.
AC Fine Test Dust (ACFTD) A test contaminant used to assess both filters and the contaminant sensitivity of all types of tribological mechanisms.
Accumulator A container in which fluid is stored under pressure as a source of fluid power.
Acid In a restricted sense, any substance containing hydrogen in combination with a nonmetal or nonmetallic radical and capable of producing hydrogen ions in solution.
Acid number The quantity of base, expressed in milligrams of potassium hydroxide, that is required to neutralize the acidic constituents in 1 g of sample.
Acid sludge The residue left after treating petroleum oil with sulfuric acid for the removal of impurities. It is a black, viscous substance containing the spent acid and impurities.
Acid treating A refining process in which unfinished petroleum products, such as gasoline, kerosene, and lubricating oil stocks, are contacted with sulfuric acid to improve their color, odor, and other properties
Acidity The presence of acid-type constituents whose concentration is usually defined in terms of neutralization number. The constituents vary in nature and may or may not markedly influence the behavior of the oil. (see neutralization number)
Actuator A device used to convert fluid energy into mechanical motion.
Additive A chemical substance added to a petroleum product to impart or improve certain properties. Common petroleum product additives are: antifoam agent, anti-wear additive, corrosion inhibitor, demulsifier, detergent, dispersant, emulsifier, EP additive, oiliness agent, oxidation inhibitor, pour point depressant, rust inhibitor, tackiness agent, viscosity index (VI.) improver.
Additive level The total percentage of all additives in an oil. (Expressed in % of mass (weight) or % of volume)
Additive stability The ability of additives in the fluid to resist changes in their performance during storage or use.
Adhesion The property of a lubricant that causes it to cling or adhere to a solid surface.
Adhesive wear Is often referred to as galling, scuffing, scoring, or seizing. It happens when sliding surfaces contact one another, causing fragments to be pulled from one surface and to adhere to the other.
Adsorbent filter A filter medium primarily intended to hold soluble and insoluble contaminants on its surface by molecular adhesion.
Adsorption Adhesion of the molecules of gases, liquids, or dissolved substances to a solid surface, resulting in relatively high concentration of the molecules at the place of contact; e.g. the plating out of an anti-wear additive on metal surfaces.
Adsorptive filtration The attraction to, and retention of particles in, a filter medium by electrostatic forces, or by molecular attraction between the particles and the medium.
Aeration The state of air being suspended in a liquid such as a lubricant or hydraulic fluid.
Agglomeration The potential of the system for particle attraction and adhesion.
AGMA lubricant numbers AGMA specification covering gear lubricants. The viscosity ranges of the AGMA numbers (or grades) conform to the International Standards Organization (ISO) viscosity classification system (see ISO viscosity classification system).
Air Bleeder A device for removal of air from a hydraulic fluid line.
Air breather A device permitting air movement between atmosphere and the component in/on which it is installed.
Air entrainment The incorporation of air in the form of bubbles as a dispersed phase in the bulk liquid. Air may be entrained in a liquid through mechanical means and/or by release of dissolved air due to a sudden change in environment. The presence of entrained air is usually readily apparent from the appearance of the liquid (i.e., bubbly, opaque, etc.) while dissolved air can only be determined by analysts.
Air motor A device which converts compressed gas into mechanical force and motion. It usually provides rotary mechanical motion.
Air, compressed Air at any pressure greater than atmospheric pressure.
Air, free Air at ambient temperature, pressure, relative humidity, and density.
Air/Oil systems A lubrication system in which small measured quantities of oil are introduced into an air/oil mixing device which is connected to a lube line that terminates at a bearing, or other lubrication point. The air velocity transports the oil along the interior walls of the lube line to the point of application. These systems provide positive air pressure within the bearing housing to prevent the ingress of contaminants, provide cooling air flow to the bearing, and perform the lubrication function with a continuous flow of minute amounts of oil.
Air-Fuel ratio The ratio of air weight to fuel wight consumed in an internal combustion engine or furnace.
Air-Gap solenoid A solenoid that is sealed to prevent leakage of the liquid indo the plunger cavity
Aliphatic A class of saturated or unsaturated carbon compounds, in which the carbon atoms are joined in open chains.
Alkali Any substance having basic (as opposed to acidic) properties. In a restricted sense it is applied to the hydroxides of ammonium, lithium, potassium and sodium. Alkaline materials in lubricating oils neutralize acids to prevent acidic and corrosive wear in internal combustion engines.
Almen EP lubricant tester A journal bearing machine used for determining the load-carrying capacity or Extreme Pressure properties (EP) of gear lubricants.
Aluminum alloy White particles which indicate wear of aluminum component such as a casing wall.
Ambient temperature Temperature of the area or atmosphere around a process, (not the operating temperature of the process itself).
Amp Ampere
Analytical ferrography The magnetic precipitation and subsequent analysis of wear debris from a fluid sample This approach involves passing a volume of fluid over a chemically treated microscope slide which is supported over a magnetic field. Permanent magnets are arranged in such a way as to create a varying field strength over the length of the substrate. This varying strength causes wear debris to precipitate in a distribution with respect to size and mass over the Ferrogram. Once rinsed and fixed to the substrate, this debris deposit serves as an excellent media for optical analysis of the composite wear particulates.
Anhydrous Devoid of water.
Aniline point The minimum temperature for complete miscibility of equal volumes of aniline and the sample under test ASTM Method D611. A product of high aniline point will be low in aromatics and naphthenes and, therefore, high in paraffins. Aniline point is often specified for spray oils, cleaning solvents, and thinners, where effectiveness depends upon aromatic content. In conjunction with API gravity, the aniline point may be used to calculate the net heat of combustion for aviation fuels.
ANSI American national standards institute
Anti-foam agent One of two types of additives used to reduce foaming in petroleum products: silicone oil to break up large surface bubbles, and various kinds of polymers that decrease the amount of small bubbles entrained in the oils.
Anti-friction bearing A rolling contact type bearing in which the rotating or moving member is supported or guided by means of ball or roller elements. Does not mean without friction.
Anti-oxidants Prolong the induction period of a base oil in the presence of oxidizing conditions and catalyst metals at elevated temperatures. The additive is consumed and degradation products increase not only with increasing and sustained temperature, but also with increases in mechanical agitation or turbulence and contamination.
Antistatic additive An additive that increases the conductivity of a hydrocarbon fuel to hasten the dissipation of electrostatic harges during high-speed dispensing, thereby reducing the fire/explosion hazard.
Antiwear additives Improve the service life of tribological elements operating in the boundary lubrication regime. Antiwear compounds (for example, zddp and tcp) start decomposing at 90 degrees to 100 degrees c and even at a lower temperature if water (25 to 50 ppm) is present.
API (American Petroleum Institute) A trade association of petroleum producers, refiners, marketers, and transporters, organized for the advancement of the petroleum industry by conducting research, gathering and disseminating information, and maintaining cooperation between government and the industry on all matters of mutual interest.
API engine service categories Gasoline and diesel engine oil quality levels established jointly by API, SAE, and ASTM, and sometimes called SAE or API/SAE categories; formerly called API Engine Service Classifications.
API gravity A gravity scale established by the American Petroleum Institute and in general use in the petroleum industry, the unit being called "the A.P.I. degree." This unit is defined in terms of specific gravity as follows:
Apparent viscosity The ratio of shear stress to rate of shear of a non-Newtonian fluid such as lubricating grease, or a multi-grade oil, calculated from Poiseuille's equation and measured in poises. The apparent viscosity changes with changing rates of shear and temperature and must, therefore, be reported as the value at a given shear rate and temperature (ASTM Method D 1092).
Aqueous decontamination Removal of a chemical or biological hazard with a water-base solution
Aromatic Derived From, or characterized by, the presence of the benzene ring.
Aromatics Group of hydrocarbons of which benzene is the parent. They are called "aromatics" because many of their derivatives have sweet or aromatic odors.
ARP Aeronautical recommended practice
Ash A measure of the amount of inorganic material in lubricating oil. Determined by burning the oil and weighing the residue. Results expressed as percent by weight.
ASLE American Society of Lubrication Engineers. Changed now to Society of Tribologist and Lubrication Engineers (STLE).
ASME American Society of Mechanical Engineers
Asperities Microscopic projections on metal surfaces resulting from normal surface-finishing processes. Interference between opposing asperities in sliding or rolling applications is a source of friction, and can lead to metal welding and scoring. Ideally, the lubricating film between two moving surfaces should be thicker than the combined height of the opposing asperities.
Asphaltenes Insoluble, semi-solid, or solid particles which are combustible and are highly aromatic. Asphaltenes contain a high carbon to hydrogen ratio and entrap water, fuel ashes and other impurities.
ASTM American Society for Testing Materials. Grade and quality specifications for petroleum products are determined by ASTM test methods.
ASTM D2670 Pin and V-Block Test ASTM Test Method D2670 is for measuring the antiwear properties of liquid lubricants. The load is applied to the jaws and maintained by a toothed wheel. The wear is a function of the number of the tooth which needs to be engaged to keep the load constant for a fixed time.
ASTM D5302 Sequence VE ASTM Test Method D 5302, the Sequence VE gasoline engine test, has been correlated with vehicles used in stop-and-go service prior to 1988, particularly with regard to sludge and valve train wear.
ASTM D5533 Sequence IIIF ASTM Test Method D 5533, the Sequence IIIE gasoline engine test, has been correlated with vehicles used in high-temperature service prior to 1988, particularly with regard to oil thickening and valve train wear.
Atm Atmosphere
Atomic absorption spectroscopy Measures the radiation absorbed by chemically unbound atoms by analyzing the transmitted energy relative to the incident energy at each frequency. The procedure consists of diluting the fluid sample with methyl isobutyl ketone (mibk) and directly aspirating the solution. The actual process of atomization involves reducing the solution to a fine spray, dissolving it, and finally vaporizing it with a flame. The vaporization of the metal particles depends upon their time in the flame, the flame temperature, and the composition of the flame gas. The spectrum occurs because atoms in the vapor state can absorb radiation at certain well-defined characteristic wave lengths. The wave length bands absorbed are very narrow and differ for each element. In addition, the absorption of radiant energy by electronic transitions from ground to excited state is essentially and absolute measure of the number of atoms in the flame and is, therefore, the concentration of the element in a sample.
Atomization The conversion of a liquid into a spray of very fine droplets.
Atomization characteristics The ability of an oil to be broken up into a fine spray by some mechanical means.
Automatic Transmission Fluid (ATF) Fluid for automatic, hydraulic transmissions in motor vehicles.
Axial-load bearing A bearing in which the load acts in the direction of the axis of rotation.

Babbitt A soft, white, non-ferrous alloy bearing material composed principally of copper, antimony, tin and lead.
Background contamination The total of the extraneous particles which are introduced in the process of obtaining, storing, moving, transferring and analyzing a fluid sample.
Bacteria Microorganisms often composed of a single cell.
Bactericide Additive included in the formulations of water-mixed cutting fluids to inhibit the growth of bacteria promoted by the presence of water, thus preventing odors that can result from bacterial action.
Baffle A device to prevent direct fluid flow or impingement on a surface.
Ball bearing An antifriction rolling type bearing containing rolling elements in the form of balls.
Barrel A unit of volume measurement used for petroleum and its products. 1 barrel = 42 U.S. gallons or 35 British gallons
Base A material which neutralizes acids. An oil additive containing colloidally dispersed metal carbonate, used to reduce corrosive wear.
Base number The amount of acid, expressed in terms of the equivalent number of milligrams of potassium hydroxide, required to neutralize all basic constituents present in 1 g of sample.
Base oil A base oil is a base stock or blend of base stocks used in an API-licensed engine oil.
Base stock The base fluid, usually a refined petroleum fraction or a selected synthetic material, into which additives are blended to produce finished lubricants.
Batch Any quantity of material handled or considered as a "unit" in processing. I.e., any sample taken from the same 'batch' will have the same properties and/or qualities.
Bbl Abbreviation for barrel.
Bearing A support or guide by means of which a moving part such as a shaft or axle is positioned with respect to the other parts of a mechanism.
Bellows seal A type of mechanical seal which utilizes bellows for providing secondary sealing and spring-type loading.
Benzene An aromatic hydrocarbon which is a colorless, volatile, flammable liquid. Benzene is obtained chiefly from coal tar and is used as a solvent for resins and fats in dye manufacture.
Bernouilli's theory If no work is done on or by a flowing, frictionless liquid, its energy, due to pressure and velocity, remains constant at all points along the streamline.
Beta rating The method of comparing filter performance based on efficiency. This is done using the multi-pass test which counts the number of particles of a given size before and after fluid passes through a filter.
Beta-Ratio The ratio of the number of particles greater than a given size in the influent fluid to the number of particles greater than the same size in the effluent fluid, under specified test conditions (see "Multi-Pass Test").
Bevel gear A straight-toothed gear with the teeth cut on sloping faces and the gear shafts at an angle (normally a right angle)
BHP Brake horsepower
Biocides Additive designed to inhibit the growth of microorganisms in liquids
Biodegradation The chemical breakdown of materials by living organisms in the environment. The process depends on certain microorganisms, such as bacteria, yeast, and fungi, which break down molecules for sustenance. Certain chemical structures are more susceptible to microbial breakdown than others; vegetable oils, for example, will biodegrade more rapidly than petroleum oils. Most petroleum products typically will completely biodegrade in the environment within two months to two years.
Bitumen Also called asphalt or tar, bitumen is the brown or black viscous residue from the vacuum distillation of crude petroleum. It also occurs in nature as asphalt "lakes" and "tar sands." it consists of high molecular weight hydrocarbons and minor amounts of sulfur and nitrogen compounds.
Black oils Lubricants containing asphaltic materials, which impart extra adhesiveness, that are used for open gears and steel cables.
Bleeding The separation of some of the liquid phase from a grease
Blender A device for mixing two fuel oils to achieve a less viscous and more uniform fuel.
Blending The process of mixing lubricants or components for the purpose of obtaining the desired physical and/or chemical properties (see compounding)
Blow-by Passage of unburned fuel and combustion gases past the piston rings of internal combustion engines, resulting in fuel dilution and contamination of the crankcase oil.
Boiling point The temperature at which a substance boils, or is converted into vapor by bubbles forming within the liquid; it varies with pressure.
Boiling range or a mixture of substances, such as a petroleum fraction, the temperature interval between the initial and final boiling points.
Bomb oxidation A test for the oxidation stability of a product obtained by sealing it in a closed container with oxygen under pressure. The drop in pressure of the oxygen is a measure of the amount of oxidation that has occurred.
Boundary lubrication Form of lubrication between two rubbing surfaces without development of a full-fluid lubricating film. Boundary lubrication can be made more effective by including additives in the lubricating oil that provide a stronger oil film, thus preventing excessive friction and possible scoring. There are varying degrees of lubrication, depending on the severity of service. For mild conditions, oiliness agents may be used; by plating out on metal surfaces in a thin but durable film, oiliness agents prevent scoring under some conditions that are too severe for a straight mineral oil. Compounded oils, which are formulated with polar fatty oils, are sometimes used for this purpose. Anti-wear additives are commonly used in more severe boundary lubrication applications. The more severe cases of boundary lubrication are defined as extreme pressure conditions; they are met with lubricants containing ep additives that prevent sliding surfaces from fusing together at high local temperatures and pressures.
Boyle's law The absolute pressure of a fixed mass of gas varies inversely as the volume, provided the temperature remains constant.
Breakdown maintenance Maintenance performed after a machine has failed to return it to an operating state.
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.
Bright stock A heavy residual lubricant stock with low pour point, used in finished blends to provide good bearing film strength, prevent scuffing, and reduce oil consumption. Usually identified by its viscosity, sus at 210|f or cst at 100|c.
Brinelling Permanent deformation of the bearing surfaces where the rollers (or balls) contact the races. Brinelling results from excessive load or impact on stationary bearings. It is a form of mechanical damage in which metal is displaced or upset without attrition.
Brookfield viscosity Apparent viscosity in cp determined by Brookfield viscometer, which measures the torque required to rotate a spindle at constant speed in oil of a given temperature. Basis for ASTM Method D 2983; used for measuring low temperature viscosity of lubricants.
BS & W Bottom sediment and water.
BS & W Monitor An instrument which detects entrained water content in petroleum products wherein the water changes the capacitive reactance as a function of the dielectric constant.
BTU British thermal unit. The amount of heat required to raise the temperature of 1 pound of water 1 degree Fahrenheit.
Bubble point The differential gas pressure at which the first steady stream of gas bubbles is emitted from a wetted filter element under specified test conditions.
Built-in-dirt Material passed into the effluent stream composed of foreign materials incorporated into the filter medium.
Bulk modulus (of elasticity) A ratio of normal stress to a change in volume. A term used in determining the compressibility of a fluid Data for petroleum products can be found in the international critical tables.
Bunker fuel oil Heavy, residual fuel oil used in ships.
Burst pressure rating The maximum specified inside-out differential pressure that can be applied to a filter element without outward structural or filter-medium failure.
Bushing A short, externally threaded connector with a smaller size internal thread.
Bypass filtration A system of filtration in which only a portion of the total flow of a circulating fluid system passes through a filter at any instant or in which a filter having its own circulating pump operates in parallel to the main flow.
Bypass valve (Relief valve) A valve mechanism that assures system fluid flow when a preselected differential pressure across the filter element is exceeded; the valve allows all or part of the flow to bypass the filter element.

C or cent. Centigrade
C/H ratio Carbon/Hydrogen ratio
CAFÉ Corporate average fuel economy
Calorie The amount of heat required to raise the temperature of 1 gram of water by 1 degree centigrade, at or near maximum density.
Calorific value Amount of heat produced by the complete combustion of a unit weight of fuel. Usually expressed in calories per gram or BTU's per pound, the latter being numerically 1.8 times the former.
Cams Eccentric shafts used in most internal combustion engines to open and close valves.
Capacity The amount of contaminants a filter will hold before an excessive pressure drop is caused. Most filters have bypass valves which open when a filter reaches its rated capacity.
Capillarity A property of a solid-liquid system manifested by the tendency of the liquid in contact with the solid to rise above or fall below the level of the surrounding liquid; this phenomenon is seen in a smallbore (capillary) tube.
Capillary viscometer A viscometer in which the oil flows through a capillary tube.
Carbon A non-metallic element - No. 6 in the periodic table. Diamonds and graphite are pure forms of carbon. Carbon isa constituent of all organic compounds. It also occurs in combined form in many inorganic substances; i.e., carbon dioxide, limestone, etc.
Carbon (deposit) Solid black residue in piston grooves which can interfere with piston ring movement leading to wear and/or loss of power.
Carbon residue Coked material remaining after an oil has been exposed to high temperatures under controlled conditions.
Carbon type The distinction between paraffinic, naphthenic, and aromatic molecules. In relation to lubricant base stocks, the predominant type present.
Carbonyl iron powder A contaminant which consists of up to 99.5% pure iron spheres.
Carcinogen A cancer-causing substance. Certain petroleum products are classified as potential carcinogens OSHA criteria. Suppliers are required to identify such products as potential carcinogens on package labels and Material Safety Data Sheets.
Cartridge seal A completely self-contained assembly including seal, gland, sleeve, mating ring, etc., usually needing no installation measurement.
Case drain filter A filter located in a line conducting fluid from a pump or motor housing to reservoir.
Case drain line A line conducting fluid from a component housing to the reservoir.
Cat Cracker A large refinery vessel for processing reduced crudes or other feed-stocks in the presence of a catalyst, as opposed to the older method of thermal cracking, which employs heat and pressure only. Catalytic cracking is generally preferred since it produces less gas and other highly volatile byproducts. It produces a motor fuel of higher octane than the thermal process.
Catalyst A substance that initiates or increases the rate of a chemical reaction, without itself being used up in the process.
Catalytic converter An integral part of vehicle emission control systems since 1975. Oxidizing converters remove hydrocarbons and carbon monoxide (co) from exhaust gases, while reducing converters control nitrogen oxide (nox) emissions. Both use noble metal (platinum, palladium or rhodium) catalysts that can be "poisoned" by lead compounds in the fuel or lubricant.
Catalytic fines Hard, abrasive crystalline particles of alumina, silica, and/or alumina silica that can be carried over from the fluidic catalytic cracking process of residual fuel stocks. Particle size can range from sub-micron to greater than sixty (60) microns in size. These particles become more common in the higher viscosity marine bunker fuels.
Catastrophic failure Sudden, unexpected failure of a machine resulting in considerable cost and downtime.
Caustic A highly alkaline substance such as sodium hydroxide.
Cavitation Formation of an air or vapor pocket (or bubble) due to lowering of pressure in a liquid, often as a result of a solid body, such as a propeller or piston, moving through the liquid; also, the pitting or wearing away of a solid surface as a result of the violent collapse of a vapor bubble. Cavitation can occur in a hydraulic system as a result of low fluid levels that draw air into the fluid, producing tiny bubbles that expand followed by rapid implosion, causing metal erosion and eventual pump destruction.
Cavitation erosion A material-damaging process which occurs as a result of vaporous cavitation. "cavitation" refers to the occurrence or formation of gas- or vapor- filled pockets in flowing liquids due to the hydrodynamic generation of low pressure (below atmospheric pressure). This damage results from the hammering action when cavitation bubbles implode in the flow stream. Ultra-high pressures caused by the collapse of the vapor bubbles produce deformation, material failure and, finally, erosion of the surfaces.
cc
Cubic centimeter
CCR
Conradson carbon residue

Cellulose media
A filter material made from plant fibers. Because cellulose is a natural material, its fibers are rough in
texture and vary in size and shape. Compared to synthetic media, these characteristics create a higher
restriction to the flow of fluids.

Celsius
Europeans use this term instead of centigrade (see below) to honor Physicist Anders Celsius. who
developed a temperature reference that uses the freezing and boiling point of water as references.

Centi
Hundredth
Centigrade
Temperature based on 0 for the temperature at which water freezes and 100 for the temperature at which
water boils. Europeans do not accept this term for Celcius. See that term above. This term is accepted
and used in North American chemical texbrooks, so which term you use may depend on your location, but
both are abbreviated with a degree symbol and capital C, so at least you now know what it means.

Centipoise
0.01 poise or centistokes times specific gravity at the test temperature.

Centipoise (cp)
A unit of absolute viscosity. 1 centipoise = 0.01 poise.

Centistoke (cst)
A unit of kinematic viscosity. 1 centistoke = 0.01 stoke.

Centralized lubrication
A system of lubrication in which a metered amount of lubricant or lubricants for the bearing surfaces of
a machine or group of machines are supplied from a central location.

Centrifugal separator
A separator that removes immiscible fluid and solid contaminants that have a different specific gravity than
the fluid being purified by accelerating the fluid mechanically in a circular path and using the radial
acceleration component to isolate these contaminants.

Centrifuge
A machine using centrifugal force produced by high-speed rotation for separating materials of different
densities. Applied to Diesel engine fuels and lubricating oils to remove moisture and other extraneous
materials.

Cetane index
An empirical measure of ignition quality. Defined as the percentage by volume of cetane in a mixture
of cetane and methyl naphthalene which has the same ignition quality when used in an engine as a fuel
under test.
cfm
Cubic feet per minute

CFR diesel fuel testing unit
A standard engine employed in making cetane number tests of Diesel engine fuels.

Channeling
The phenomenon observed among gear lubricants and greases when they thicken due to cold weather
or other causes, to such an extent that a groove is formed through which the part to be lubricated moves
without actually coming in full contact with the lubricant. A term used in percolation filtration; may be defined
as: a preponderance of flow through certain portions of the clay bed.

Chemical stability
The tendency of a substance or mixture to resist chemical change.

Chip control (grit control, last-chance) filter
A filter intended to prevent only large particles from entering a component immediately downstream.

Chlorinated wax
Certain solid hydrocarbons treated with chlorine gas to form straight-chain hydrocarbons with a relatively
high chlorine component. Chlorinated waxes are used primarily as polyvinyl chloride plasticizers,
extreme-pressure additives for lubricants, and formulation components for many cutting fluids.

Chromatography
An analytical technique whereby a complex substance is adsorbed on a solid or liquid substrate and
progressively eluted by a flow of a substance (the eluant) in which the components of the substance under
investigation are differentially soluble. The eluant can be a liquid or a gas. When the substrate is filter paper
and the eluant a liquid, a chromatogram of colored bands can be developed by use of indicators. For
gas chromatography, electronic detectors are normally used to indicate passage of the various
components from the system.

Circulating header system
A lubrication system having isolated lube zones wherein the lube pump runs continuously and circulates
oil through the header, a return filter and back to tank during the idle period. When lubrication is required,
a normal open solenoid valve in the return loop is actuated, allowing pump pressure to build. The zone
valves are then sequentially opened to provide lubricant to the individual zones. Oil dispensed to the
friction points is not reused, therefore, the system is a terminating type.

Circulating lubrication
A system of lubrication in which the lubricant, after having passed through a bearing or group of
bearings, is recirculated by means of a pump.

Circulating oil
A lubrication system wherein the oil pump runs continuously and circulates oil to the friction points on
a continuous basis. The oil is drained back to tank, filtered, cooled as required and reused.

Circulating system
A lubricating system in which oil is recirculated from a central sump to the parts requiring lubrication
and then returned to the sump.

Clarifier
A machine used for a liquid-sludge separation in which the particles with a higher specific gravity are
separated form the lower specific gravity of the liquid. A clarifier bowl has one outlet for the light phase
oil; the heavier phase particles are retained on the bowl wall.

Clay filtration
A refining process using fuller's earth (activated clay), bauxite or other mineral to absorb minute solids
from lubricating oil, as well as remove traces of water, acids, and polar compounds.

Clean
100 particles >10 micron per milliliter

Clean room
A facility or enclosure in which air content and other conditions (such as temperature, humidity, and
pressure) are controlled and maintained at a specific level by special facilities and operating processes
and by trained personnel.

Cleanable
A filter element which, when loaded, can be restored by a suitable process, to an acceptable percentage
of its original dirt capacity.

Cleanliness level (CL)
A measure of relative freedom from contaminants.

Clearance bearing
A journal bearing in which the radius of the bearing surface is greater than the radius of the journal surface.

Cleveland open cup (COC)
A flash point test in which the surface of the sample is completely open to the atmosphere, and which
is therefore relatively insensitive to small traces of volatile contaminants.

Cloud point
The temperature at which waxy crystals in an oil or fuel form a cloudy appearance.

cm
Centimeter

Coalescor
A separator that divides a mixture or emulsion of two immiscible liquids using the interfacial tension
between the two liquids and the difference in wetting of the two liquids on a particular porous medium.

Coefficient of friction
The number obtained by dividing the friction force resisting motion between two bodies by the normal
force pressing the bodies together.

Cohesion
That property of a substance that causes it to resist being pulled apart by mechanical means.

Coking
The undesirable accumulation of carbon (coke) deposits in the internal combustion engine or in a refinery
plant. The process of distilling a petroleum product to dryness.

Cold cranking simulator (CCS)
An intermediate shear rate viscometer that predicts the ability of an oil to permit a satisfactory cranking
speed to be developed in a cold engine.

Collapse
An inward structural failure of a filter element which can occur due to abnormally high pressure drop
(differential pressure) or resistance to flow.

Collapse pressure
The minimum differential pressure that an element is designed to withstand without permanent deformation.

Complex grease
A lubricating grease thickened by a complex soap consisting of a normal soap and a complexing agent.

Compound
(1) chemically speaking, a distinct substance formed by the combination of two or more elements in
definite proportions by weight and possessing physical and chemical properties different from those of the
combining elements. (2) in petroleum processing, generally connotes fatty oils and similar materials
foreign to petroleum added to lubricants to impart special properties.

Compounded oil
A petroleum oil to which has been added other chemical substances.

Compounding
The addition of fatty oils and similar materials to lubricants to impart special properties. Lubricating
oils to which such materials have been added are known as compounded oils.

Compressibility
A compound that enhances some property of, or imparts some new property to, the base fluid. In some
hydraulic fluid formulations, the additive volume may constitute as much as 20 percent of the final
composition. The more important types of additives include anti-oxidants, anti-wear additives, corrosion
inhibitors, viscosity index improvers, and foam suppressants.

Compression ratio
In an internal combustion engine, the ratio of the volume of combustion space at bottom dead center
to that at top dead center.

Compressor
A device which converts mechanical force and motion into pneumatic fluid power.

Consistency
The degree to which a semisolid material such as grease resists deformation. (see astm designation
d 217.) Sometimes used qualitatively to denote viscosity of liquids.

Contaminant
Any foreign or unwanted substance that can have a negative effect on system operation, life or reliability.

Contaminant (Dirt, ACFTD) capacity
The weight of a specified artificial contaminant that must be added to the influent to produce a given
differential pressure across a filter at specified conditions. Used as an indication of relative service life.

Contaminant failure
Any loss of performance due to the presence of contamination. Two basic types of contamination
failure are: perceptible

Contaminant lock
A particle or fiber-induced jam caused by solid contaminants.

Contamination control
A broad subject which applies to all types of material systems (including both biological and engineering).
It is concerned with planning, organizing, managing, and implementing all activities required to determine,
achieve and maintain a specified contamination level.

Coolant
A fluid used to remove heat. See cutting fluid.

Copper strip corrosion
The gradual eating away of copper surfaces as the result of oxidation or other chemical action. It is
caused by acids or other corrosive agents.

Core
The internal duct and filter media support.

Corrosion
The decay and loss of a metal due to a chemical reaction between the metal and its environment. It is a
transformation process in which the metal passes from its elemental form to a combined (or compound) form.

Corrosion inhibitor
Additive for protecting lubricated metal surfaces against chemical attack by water or other contaminants.
There are several types of corrosion inhibitors. Polar compounds wet the metal surface preferentially,
protecting it with a film of oil. Other compounds may absorb water by incorporating it in a water-in-oil
emulsion so that only the oil touches the metal surface. Another type of corrosion inhibitor combines
chemically with the metal to present a non-reactive surface.

Coupling
A straight connector for fluid lines.

Coupling, quick disconnect
A coupling which can quickly join or separate lines.

Cracked
Refers to a petroleum product produced by a secondary refining process such as thermal cracking or
vis-breaking processes which yield very low quality residue.

Cracking
The process whereby large molecules are broken down by the application of heat and pressure to form
smaller molecules.

Crankcase oil
Lubricant used in the crankcase of the internal combustion engine.

Crown
The top of the piston in an internal combustion engine above the fire ring, exposed to direct flame
impingement.
Cryogenics
The branch of physics relating to the production and effects of very low temperatures.

cSt
Centistokes @ 50 Centigrade

Cutter stock
Flux Stock. A petroleum stock which is used to reduce the viscosity of a heavier residual stock by dilution.

Cutting fluid
Any fluid applied to a cutting tool to assist in the cutting operation by cooling, lubricating or other means.

Cutting oil
A lubricant used in machining operations for lubricating the tool in contact with the workpiece, and to
remove heat. The fluid can be petroleum based, water based, or an emulsion of the two. The term
"emulsifiable cutting oil" normally indicates a petroleum-based concentrate to which water is added to
form an emulsion which is the actual cutting fluid.

Cycle
A single complete operation consisting of progressive phases starting and ending at the neutral position.

Cylinder
A device which converts fluid power into linear mechanical force and motion. It usually consists of a
moveable element such as a piston and piston rod, plunger rod, plunger or ram, operating with in
a cylindrical bore.

Cylinder oil
A lubricant for independently lubricated cylinders, such as those of steam engines and air compressors;
for lubrication of valves and other elements in the cylinder area. Steam cylinder oils are available in a
range of grades with high viscosities to compensate for the thinning effect of high temperatures; of these,
the heavier grades are formulated for super-heated and high-pressure steam, and the less heavy grades
for wet, saturated, or low-pressure steam. Some grades are compounded for service in excessive
moisture; see compounded oil. Cylinder oils lubricate on a once-through basis.

Deaerator A separator that removes air from the system fluid through the application of bubble dynamics.
Degas
Removing air from a liquid, usually by ultrasonic and/or vacuum methods.

Degradation
The progressive failure of a machine or lubricant.

Dehydrator
A separator that removes water from the system fluid.

Delamination wear
A complex wear process where a machine surface is peeled away or otherwise removed by forces
of another surface acting on it in a sliding motion.

Demulsibility
The resistance of an oil to emulsification, or the ability of an oil to separate from any water with which it is
mixed. The better the demulsibility rating, the more quickly the oil separates from water.

Demulsifier
An additive that promotes oil-water separation in lubricants that are exposed to water or steam.

Density
The mass of a unit volume of a substance. Its numerical value varies with the units used.

Deplete
The depletion of additives expressed as an approximate percentage.

Deposits
Oil-insoluble materials that result from oxidation and decomposition of lube oil and contamination
from external sources and engine blow-by. These can settle out on machine or engine parts. Examples
are sludge, varnish, lacquer and carbon.

Depth filter
A filter medium that retains contaminants primarily within tortuous passages.

Dermatitis
Inflammation of the skin. Repeated contact with petroleum products can be a cause.

Desalter
The desalter mixes the hydrocarbon stream with a small amount of fresh water (e.g. 10% by volume)
forming a water-in-oil emulsion. The resulting emulsion is subjected to an electric field wherein the
water is coalesced as an under flow from the upper flow of a relatively water-free, continuous hydrocarbon
phase. The desalted hydrocarbon stream is produced at relatively low cost and has a very small residual
salt content. The performance of this unit can be improved with a demulsifier, such as Alken 860 Demulsifier.

Desorption
Opposite of absorption or adsorption. In filtration, it relates to the downstream release of particles
previously retained by the filter.

Detergent
In lubrication, either an additive or a compounded lubricant having the property of keeping insoluble
matter in suspension thus preventing its deposition where it would be harmful. A detergent may also
redisperse deposits already formed.

Detergent oil
Is a lubricating oil possessing special sludge-dispersing properties usually conferred on the oil by the
incorporation of special additives. Detergent oils hold formed sludge particles in suspension and thus
promote cleanliness especially in internal-combustion engines. However detergent oils do not contain
"detergents" such as those used for cleaning of laundry or dishes. Also detergent oils do not clean
already “dirty” engines, but rather keep in suspension the sludge that petroleum oil forms so that the
engine remains cleaner for longer period. The formed sludge particles are either filtered out by Oil Filters
or drained out when oil is changed.

Detonation
A violent explosion involving high-velocity pressure waves; in a gasoline engine, the spontaneous
combustion of part of the compresses charge after spark occurs. Detonation usually produces a
characteristic metallic sound, or knock.

Dewaxing
Removal of wax from a base oil in order to reduce the pour point.

Dielectric strength
A measure of the ability of an insulating material to withstand electric stress (voltage) without failure.
Fluids with high dielectric strength (usually expressed in volts or kilovolts) are good electrical insulators.
(astm designation d 877.)

Diesel index
Product of the API gravity and the aniline point (in degrees Fahrenheit) of a Diesel fuel, divided by 100;
an indication of the ignition quality of the fuel.

Differential pressure indicator
An indicator which signals the difference in pressure between any two points of a system or a component.

Dirt capacity (dust capacity) (contaminant capacity)
The weight of a specified artificial contaminant which must be added to the influent to produce a given
differential pressure across a filter at specified conditions. Used as an indication of relative service life.

Dispersant
In lubrication, a term usually used interchangeably with detergent. An additive, usually nonmetallic
("ashless"), which keeps fine particles of insoluble materials in a homogeneous solution. Hence, particles
are not permitted to settle out and accumulate.

Disposable
A filter element intended to be discarded and replaced after one service cycle.

Dissolved air
Air which is dispersed in a fluid to form a mixture.

Dissolved gases
Those gases that enter into solution with a fluid and are neither free nor entrained gases.

Dissolved water
Water which is dispersed in the fluid to form a mixture.

Distillation method (ASTM D-95)
A method involving distilling the fluid sample in the presence of a solvent that is miscible in the sample
but immiscible in water. The water distilled from the fluid is condensed and segregated in a
specially-designed receiving tube or tray graduated to directly indicate the volume of water distilled.

Distillation
The process of heating a liquid to its boiling point and condensing and collecting the vapors

Doctor test
A qualitative method of detecting undesirable sulfur compounds in petroleum distillates, that is, of
determining whether oil is "sour" or "sweet".

Double seal
Two mechanical seals designed to permit a liquid or gas barrier fluid between the seals mounted
back-to-back or face-to-face.

Drag
The resistance to movement caused by oil viscosity.

Dropping point
In general, the dropping point is the temperature at which the grease passes from a semisolid to a
liquid state. This change in state is typical of greases containing conventional soap thickeners. Greases
containing thickeners other than conventional soaps may, without change in state, separate oil.

Drum
A container with a capacity of 55 U.S. gallons.

Dry lubrication
The situation when moving surfaces have no liquid lubricant between them.

Dry sump
An engine design in which oil is not retained in a pan beneath the crankshaft thus permitting splash
lubrication. There may be a remote sump from which oil is recirculated, or there may be a total loss system.

Dual-Line system
A positive displacement terminating (oil, or grease) lubrication system that employs two main lines
supplied from a pump connected to a 4-way (reverser) valve. Pressure in one main line (while the other is
open to tank) causes the measuring piston(s) in the dual-line valve(s) to stroke in one direction dispensing
lubricant to one group of lube points. Switching the 4-way (reverser) valve directs pump flow to the
second main line and opens the first main line to tank. This allows pressure to build in the second main
line causing the dual-line valve(s) measuring piston(s) to stroke back to their original position dispensing
lubricant to a second group of lube points. The system is a parallel type and each dual-line valves
operates independently of any other in the system.

Duplex filter
An assembly of two filters with valving for selection of either or both filters.

Dynamic seal
A seal that moves due to axial or radial movement of the unit.

Effluent
The fluid leaving a component.

Elastohydrodynamic lubrication
In rolling element bearings, the elastic deformation of the bearing (flattening) as it rolls, under load, in
the bearing race. This momentary flattening improves the hydrodynamic lubrication properties by
converting point or line contact to surface-to-surface contact.

Elastomer
A rubber or rubber-like material, both natural and synthetic, used in making a wide variety of products,
such as seals and hoses. In oil seals, an elastomer's chemical composition is a factor in determining
its compatibility with a lubricant.

Electrical insulating oil
A high-quality oxidation-resistant oil refined to give long service as a dielectric and coolant for electrical
equipment, most commonly transformers. An insulating oil must resist the effects of elevated temperatures,
electrical stress, and contact with air, which can lead to sludge formation and loss of insulation properties.
It must be kept dry, as water is detrimental to dielectric strength - the minimum voltage required to
produce an electric arc through an oil sample, as measured by test method ASTM D 877.

Electrolytic process
A process that causes the decomposition of a chemical compound by the use of electricity.

Electrostatic separator
A separator that removes contaminant from dielectric fluids by applying an electrical charge to the
contaminant that is then attracted to a collection device of different electrical charge.

Element (Cartridge)
The porous device that performs the actual process of filtration.

Emission spectrometer
Works on the basis that atoms of metallic and other particular elements emit light at characteristic
wavelengths when they are excited in a flame, arc, or spark. Excited light is directed through an entrance
slit in the spectrometer. This light penetrates the slit, falls on a grate, and is dispersed and reflected. The
spectrometer is calibrated by a series of standard samples containing known amounts of the elements
of interest. By exciting these standard samples, an analytical curve can be established which gives the
relationship between the light intensity and its concentration in the fluid.

Emulsibility
The ability of a non-water-soluble fluid to form an emulsion with water.

Emulsifier
Additive that promotes the formation of a stable mixture, or emulsion, of oil and water. Common emulsifiers
are: metallic soaps, certain animal and vegetable oils, and various polar compounds.

Emulsion
A liquid mixture of two or more liquid substances not normally dissolved in one another, one liquid held in
suspension in the other. Water-in-oil emulsions have water as the internal phase and oil as the external,
while oil-in-water have oil as the internal phase and water as the external.

End cap
A ported or closed cover for the end of a filter element.

Engine deposits
Hard or persistent accumulation of sludge, varnish and carbonaceous residues due to blow-by of unburned
and partially burned fuel, or the partial breakdown of the crankcase lubricant. Water from the condensation
of combustion products, carbon, residues from fuel or lubricating oil additives, dust and metal particles
also contribute.

Engler viscosity
A viscosity obtained by dividing the out-flow time in seconds for 200 ml. of the material being tested, by
the time in seconds for 200 ml. of water at 68F (20C) to flow out of an Engler viscosimeter.

Entrained air
A mechanical mixture of air bubbles having a tendency to separate from the liquid phase.

Environmental contaminant
All material and energy present in and around an operating system, such as dust, air moisture,
chemicals, and thermal energy.

EP (Extreme Pressure) lubricants
Lubricants that impart to rubbing surfaces the ability to carry appreciably greater loads than would be
possible with ordinary lubricants without excessive wear or damage.

EP oil
A lubricating oil formulated to withstand extreme pressure (EP) operating conditions.

Erosion
The progressive removal of a machine surface by cavitation or by particle impingement at high velocities.

Externally pressurized seal
A seal that has pressure acting on the seal parts from an external independent source of supply.

Extreme pressure (EP) additive
Lubricant additive that prevents sliding metal surfaces from seizing under conditions of extreme pressure.
At the high local temperatures associated with metal-to-metal contact, an ep additive combines chemically
with the metal to form a surface film that prevents the welding of opposing asperities, and the consequent scoring that is destructive to sliding surfaces under high loads. Reactive compounds of sulfur, chlorine, or
phosphorus are used to form these inorganic films.

Fabrication integrity point
The differential gas pressure at which the first stream of gas bubbles are emitted from a wetted filter
element under standard test conditions.

Face seal
A device that prevents leakage of fluids along rotating shafts. Sealing is accomplished by a stationary
primary seal ring bearing against the face of a mating ring mounted on a shaft. Axial pressure maintains
the contact between the seal ring and the mating ring.

Fahrenheit
Temperature scale based on 32F for the temperature at which water freezes and 212F for the temperature
at which water boils (180 difference). Conversion to Farhenheit from Celsius (centigrade) temperature
scale is by the following formula: F = 9/5C + 32, where C is the temperature in Celsius degrees.

False brinelling
False brinelling of needle roller bearings is actually a fretting corrosion of the surface since the rollers are the I.D. of the bearing. Although its appearance is similar to that of brinelling, false brinelling is
characterized by attrition of the steel, and the load on the bearing is less than that required to produce the
resulting impression. It is the result of a combination of mechanical and chemical action that is not
completely understood, and occurs when a small relative motion or vibration is accompanied by some loading, in the presence of oxygen.

Fat
An animal or vegetable oil which will combine with an alkali to saponify and form a soap.

Fatigue chunks
Thick three-dimensional particles exceeding 50 microns indicating severe wear of gear teeth.

Fatigue life
The theoretical number of revolutions (or hours of operation) a bearing will last under a given constant
load and speed before the first evidence of fatigue develops on one or more of the components.

Fatigue platelets
Normal particles between 20 and 40 microns found in gear box and rolling element bearing oil samples
observed by analytical ferrography. A sudden increase in the size and quantity of these particles indicates
excessive wear.

Fatigued
A structural failure of the filter medium due to flexing caused by cyclic differential pressure.

Ferrography
An analytical method of assessing machine health by quantifying and examining ferrous wear particles
suspended in the lubricant or hydraulic fluid.

Fiber grease
A grease with a distinctly fibrous structure, which is noticeable when portions of the grease are pulled apart.

Film strength
Property of a lubricant that acts to prevent scuffing or scoring of metal parts.

Filter
Any device or porous substance used as a strainer for cleaning fluids by removing suspended matter.

Filter Efficiency
Method of expressing a filter's ability to trap and retain contaminants of a given size.

Filter element
The porous device which performs the actual process of filtration.

Filter head
An end closure for the filter case or bowl that contains one or more ports.

Filter housing
A ported enclosure that directs the flow of fluid through the filter element.

Filter life test
A type of filter capacity test in which a clogging contaminant is added to the influent of a filter, under
specified test conditions, to produce a given rise in pressure drop across the filter or until a specified
reduction of flow is reached. Filter life may be expressed as test time required to reach terminal conditions at a specified contaminant addition rate.

Filter media, depth
Porous materials which primarily retain contaminants within a tortuous path, performing the actual
process of filtration.

Filter media, surface
Porous materials which primarily retain contaminants on the influent face, performing the actual process of filtration.

Filtration
The physical or mechanical process of separating insoluble particulate matter from a fluid, such as air
or liquid, by passing the fluid through a filter medium that will not allow the particulates to pass through it.

Filtration (Beta) ratio
The ratio of the number of particles greater than a given size in the influent fluid to the number of particles
greater than the same size in the effluent fluid.

Final boiling point (FBP)
The highest temperature indicated on the thermometer inserted in the flask during a standard laboratory
distillation. This is generally the temperature at which no more vapor can be driven over into the condensing
apparatus.

Fire point (Clevelend Open Cup)
The temperature to which a combustible liquid must be heated so that the released vapor will burn
continuously when ignited under specified conditions.

Fire point
The lowest temperature at which an oil vaporizes rapidly enough to burn for at least 5 seconds after
ignition, under standard conditions.

Fire-resistant fluid
Lubricant used especially in high-temperature or hazardous hydraulic applications. Three common
types of fire-resistant fluids are: (1) water-petroleum oil emulsions, in which the water prevents burning
of the petroleum constituent; (2) water-glycol fluids; and (3) non-aqueous fluids of low volatility, such as
phosphate esters, silicones, and halogenated hydrocarbon-type fluids.

Flash point (Cleveland Open Cup)
The temperature to which a combustible liquid must be heated to give off sufficient vapor to form
momentarily a flammable mixture with air when a small flame is applied under specified conditions.
(astm designation d 92.)

Flash point
The lowest temperature at which a liquid will generate sufficient vapor to flash (ignite) when exposed to
a source of ignition.

Floc Point
The temperature at which wax or solids separate in an oil

Flow fatigue rating
The ability of a filter element to resist a structural failure of the filter medium due to flexing caused by
cyclic differential pressure.

Flow rate
The volume, mass, or weight of a fluid passing through any conductor per unit of time.

Flow, laminar
A flow situation in which fluid moves in parallel lamina or layers.

Flow, turbulent
A flow situation in which the fluid particles move in a random manner.

Flowmeter
A device which indicates either flow rate, total flow, or a combination of both.

Fluid
A general classification including liquids and gases.

Fluid compatibility
The suitability of filtration medium and seal materials for service with the fluid involved.

Fluid friction
Friction due to the viscosity of fluids.

Fluid opacity
Related to the ability of a fluid to pass light.

Fluid power
Energy transmitted and controlled through use of a pressurized fluid.

Fluid, fire resistant
A fluid difficult to ignite which shows little tendency to propagate flame.

Flushing
A fluid circulation process designed to remove contamination from the wetted surfaces of a fluid system.

Foam
An agglomeration of gas bubbles separated from each other by a thin liquid film which is observed as a
persistent phenomenon on the surface of a liquid.

Foam inhibitor
A substance introduced in a very small proportion to a lubricant or a coolant to prevent the formation of
foam due to aeration of the liquid, and to accelerate the dissipation of any foam that may form

Foaming
A frothy mixture of air and a petroleum product (e.g., lubricant, fuel oil) that can reduce the effectiveness
of the product, and cause sluggish hydraulic operation, air binding of oil pumps, and overflow of tanks or
sumps. Foaming can result from excessive agitation, improper fluid levels, air leaks, cavitation, or
contamination with water or other foreign materials. Foaming can be inhibited with an antifoam agent. The
foaming characteristics of a lubricating oil can be determined by blowing air through a sample at a specified
temperature and measuring the volume of foam, as described in test method ASTM D 892.

Force feed lubrication
A system of lubrication in which the lubricant is supplied to the bearing surface under pressure.

Force Majeure
A standard clause which indemnifies either or both parties to a transaction whenever events reasonably
beyond the control of either or both parties occur to prevent fulfillment of the terms of the contract.

Four Ball Tester
This name is frequently used to describe either of two similar laboratory machines, the Four-Ball Wear
Tester and the Four-Ball EP Tester. These machines are used to evaluate a lubricant's anti-wear qualities,
frictional characteristics or load carrying capabilities. It derives its name from the four 1/2 inch steel balls
used as test specimens. Three of the balls are held together in a cup filled with lubricant while the fourth
ball is rotated against them.

Fraction
A separate identifiable part of crude oil; the product of a refining or

Free Water
Water droplets or globules in the system fluid that tend to accumulate at the bottom or top of the system
fluid depending on the fluid's specific gravity.

Fretting
Wear phenomena taking place between two surfaces having oscillatory relative motion of small amplitude.

Fretting corrosion
Can take place when two metals are held in contact and subjected to repeated small sliding, relative
motions. Other names for this type of corrosion include wear oxidation, friction oxidation, chafing, and .
brinelling

Friction
The resisting force encountered at the common boundary between two bodies when, under the action
of an external force, one body, moves or tends to move relative to the surface of the other.

FTIR = Fourier Transform Infrared Spectroscopy
A test where infrared light absorption is used for assessing levels of soot, sulfates, oxidation, nitro-oxidation,
glycol, fuel, and water contaminants.

Fuel oil
The heavy distillates from the oil refining process; used as fuel for power stations, marine boilers.

Full flow filter
A filter that, under specified conditions, filters all influent flow.

Full-flow filtration
A system of filtration in which the total flow of a circulating fluid system passes through a filter

Full-fluid-film lubrication
Presence of a continuous lubricating film sufficient to completely separate two surfaces, as distinct from
boundary lubrication. Full-fluid-film lubrication is normally hydrodynamic lubrication, whereby the oil
adheres to the moving part and is drawn into the area between the sliding surfaces, where it forms a
pressure.

Fungible
Interchangeable. Products which can be commingled for purposes of pipeline shipment.

FZG test
A German gear test for evaluating EP properties.

Gage
An instrument or device for measuring, indicating or comparing a physical characteristic.

Galling
A form of wear in which seizing or tearing of the gear or bearing surface occurs.

Gasohol
A blend of 10% anhydrous ethanol (ethyl alcohol) and 90% gasoline, by volume. Used as a motor fuel.

Gasoil
Designation for No.2 heating oils and diesel fuels. A clean distillate fuel oil.

Gear
A machine part which transmits motion and force by means of successively engaging projections, called
teeth. The smaller gear of a pair is called the pinion; the larger, the gear. When the pinion is on the driving
shaft, the gear set acts as a speed reducer; when the gear drives, the set acts as a speed multiplier. The basic gear type is the spur gear, or straight-tooth gear, with teethe cut parallel to the gear axis. Spur gears

transmit power in applications utilizing parallel shafts. In this type of gear, the teeth mesh along their full
length, creating a sudden shift in load from one tooth to the next, with consequent noise and vibration. This
problem is overcome by the helical gear, which has teeth cut at an angle to the center of rotation, so that the
load is transferred progressively along the length of the tooth from one edge of the gear to the other. When the
shafts are not parallel, the most common gear type used is the bevel gear, with teeth cut on a sloping gear
face, rather than parallel to the shaft. The spiral bevel gear has teeth cut at an angle to the plane of rotation,
which, like the helical gear, reduces vibration and noise. A hypoid gear resembles a spiral bevel gear, except
that the pinion is offset so that its axis does not intersect the gear axis; it is widely used in automobiles
between the engine driveshaft and the rear axle. Offset of the axes of hypoid gears introduces additional
sliding between the teeth, which, when combined with high loads, requires a high-quality EP oil. A worm
gear consists of a spirally grooved screw moving against a tooth wheel; in this type of gear, where the load
is transmitted across sliding, rather than rolling surfaces, compounded oils or EP oils are usually
necessary to maintain effective lubrication.

Gear oil
A high-quality oil with good oxidation stability, load-carrying capacity, rust protection, and resistance to
foaming, for service in gear housings and enclosed chain drives. Specially formulated industrial EP gear
oils are used where highly loaded gear sets or excessive sliding action (as in worm gears) is encountered.

Gearbox (gear housing)
A casing for gear sets that transmit power from one rotating shaft to another. A gear box has a number of
functions: it is precisely bored to control gear and shaft alignment, it contains the gear oil, and it protects the
gears and lubricant from water, dust, and other environmental contaminants. Gear boxes are used in a
wide range of industrial, automotive, and home machinery. Not all gears are enclosed in gear boxes;
some are open to the environment and are commonly lubricated by highly adhesive greases.

Generated contaminant
Caused by a deterioration of critical wetted surfaces and materials or by a breakdown of the fluid itself.

GPM
Gallons per minute

Graphite
A crystalline form of carbon having a laminar structure, which is used as a lubricant. It may be of natural
or synthetic origin.

Gravimetric analysis
A method of analysis whereby the dry weight of contaminant per unit volume of fluid can be measured
showing the degree of contamination in terms of milligrams of contaminant per litre of fluid.

Gravity
See specific gravity; api gravity.

Grease
A lubricant composed of an oil or oils thickened with a soap, soaps or other thickener to a semisolid or
solid consistency.

Hardness
The resistance of a substance to surface abrasion.

Head
An end closure for the filter case or bowl which contains one or more ports.

Heat exchanger
A device which transfers heat through a conducting wall from one fluid to another.

Heat of combustion gross
Total heat evolved during complete combustion of unit weight of a substance, usually expresses in
BTU per pound.

Heat of combustion net
Gross heat of combustion minus the latent heat of condensation of any water produced.

Heavy crude
Crude oil with a high specific gravity and a low API gravity due to the presence of a high proportion of heavy
hydrocarbon fractions and metallic content.

Heavy ends
The portions of a petroleum distillate fraction which are highest boiling, and therefore distill over last if the .
temperature is raised progressively

HHV
Higher heating value

Homogenizer
A mechanical device which is used to create a stable, uniform dispersion of an insoluble phase
(asphaltenes) within a liquid phase (fuel oil).

Housing
A ported enclosure which directs the flow of fluid through the filter element.

hp or HP
Horsepower

HVI
High Viscosity Index, typically from 80 to 110 VI units.

Hydraulic fluid
Fluid serving as the power transmission medium in a hydraulic system. The most commonly used fluids
are petroleum oils, synthetic lubricants, oil-water emulsions, and water-glycol mixtures. The principal
requirements of a premium hydraulic fluid are proper viscosity, high viscosity index, anti-wear protection (if
needed), good oxidation stability, adequate pour point, good demulsibility, rust inhibition, resistance to
foaming, and compatibility with seal materials. Anti-wear oils are frequently used in compact, high-pressure,
and capacity pumps that require extra lubrication protection.

Hydraulic motor
A device which converts hydraulic fluid power into mechanical force and motion by transfer of flow under
pressure. It usually provided rotary mechanical motion.

Hydraulic oil
An oil specially suited for use as either the specific gravity or the API gravity of a liquid.

Hydraulic pump
A device which converts mechanical force and motion into hydraulic fluid power by means of producing flow.

Hydraulic system
A system designed to transmit power through a liquid medium, permitting multiplication of force in
accordance with Pascal's law, which stated that "a pressure exerted on a confined liquid is transmitted
undiminished in all directions and acts with equal force on all equal areas." Hydraulic systems have six basic
components: (1) a reservoir to hold the fluid supply; (2) a fluid to transmit the power; (3) a pump to move the
fluid; (4) a valve to regulate pressure; (5) a directional valve to control the flow, and (6) a working component
- such as a cylinder and piston or a shaft rotated by pressurized fluid - to turn hydraulic power into mechanical
motion. Hydraulic systems offer several advantages over mechanical systems: They eliminate complicated
mechanisms such as cams, gears, and levers; are less subject to wear; are usually more easily adjusted
for control of speed and force; are easily adaptable to both rotary and liner transmission of power; and can
transmit power over long distances and in any direction with small losses.

Hydraulics
Engineering science pertaining to liquid pressure and flow.

Hydrocarbons
Compounds containing only carbon and hydrogen. Petroleum consists chiefly of hydrocarbons.

Hydrodynamic lubrication
A system of lubrication in which the shape and relative motion of the sliding surfaces causes the formation
of a fluid film having sufficient pressure to separate the surfaces.

Hydrofinishing
A process for treating raw extracted base stocks with hydrogen to saturate them for improved stability.

Hydrogenation
In refining, the chemical addition of hydrogen to a hydrocarbon in the presence of a catalyst; a severe form of
hydrogen treating. Hydrogenation may be either destructive or non-destructive. In the former case,
hydrocarbon chains are ruptured (cracked) and hydrogen is added where the breaks have occurred. In the latter, hydrogen is added to a molecule that is unsaturated with respect ot hydrogen. In either case, the
resulting products are highly stable. Temperatures and pressures in the hydrogenation process are usually
greater than in hydrofining.

Hydrolysis
Breakdown process that occurs in anhydrous hydraulic fluids as a result of heat, water, and metal catalysts
(iron, steel, copper, etc.)

Hydrolytic stability
Ability of additives and certain synthetic lubricants to resist chemical decomposition (hydrolysis) in the
presence of water.

Hydrometer
An instrument for determining either the specific gravity of a liquid or the API gravity.

Hydrometer
An instrument for determining the gravity of a liquid.

Hydrophilic
Compounds with an affinity for water.

Hydrophobic
Compounds that repel water.

Hydrostatic lubrication
A system of lubrication in which the lubricant is supplied under sufficient external pressure to separate the
opposing surfaces by a fluid film.

Hypoid gear lubricant
A gear lubricant having extreme pressure characteristics for use with a hypoid type of gear as in the
differential of an automobile.

Hypoid gears
Gears in which the pinion axis intersects the plane of the ring gear at a point below the ring-gear axle and
above the outer edge of the ring gear, or above the ring-gear axle and below the outer edge of the ring gear.

Hz
Hertz (cycles per second)

IBP
Initial Boiling Point. In a standard laboratory distillation, the temperature on the distillation thermometer at
the moment the first drop of distillate falls from the condenser.

ILMA
The Independent Lubricant Manufacturers Association (ILMA) is a trade association of businesses
engaged in compounding, blending, formulating, packaging, marketing, and distributing lubricants.

ILSAC
The International Lubricant Standardization and Approval Committee (ILSAC) is a joint committee of AAMA
and JAMA members that assists in the development of new minimum oil performance standards.

Image analyzer
A sophisticated microscopic system involving a microscope, a television camera, a dedicated computer,
and a viewing monitor similar to a television screen.

Immiscible
Incapable of being mixed without separation of phases. Water and petroleum oil are immiscible under
most conditions, although they can be made miscible with the addition of an emulsifier.

Incompatible fluids
Fluids which when mixed in a system, will have a deleterious effect on that system, its components or its
operation.

Indicator
A device which provides external evidence of sensed phenomena.

Indicator, differential pressure
An indicator which signals the difference in pressure between two points, typically between the upstream
and downstream sides of a filter element.

Indicator, pressure
An indicator that signals pressure conditions.

Industrial lubricant
Any petroleum or synthetic-base fluid or grease commonly used in lubricating industrial equipment, such as
gears, turbines, and compressors.

Influent
The fluid entering a component.

Infrared (IR) analysis
A form of absorption spectroscopy that identifies organic functional groups present in a used oil sample by
measuring their light absorption at specific infrared wavelengths; absorbance is proportional to concentration.
The test can indicate additive depletion, the presence of water, hydrocarbon contamination of a synthetic lubricant, oxidation, nitration, and glycol contamination from coolant. Fourier Transform Infrared (FTIR)
permits the generation of complex curves from digitally represented data.

Infrared spectra
A graph of infrared energy absorbed at various frequencies in the additive region of the infrared spectrum.
The current sample, the reference oil and the previous samples are usually compared.

Infrared spectroscopy
An analytical method using infrared absorption for assessing the properties of used oil and certain
contaminants suspended therein. See ftir.

Ingested contaminants
Environmental contaminant that ingresses due to the action of the system or machine.

Ingression level
Particles added per unit of circulating fluid volume.

Inhibitor
Any substance that slows or prevents such chemical reactions as corrosion or oxidation.

In-line filter
A filter assembly in which the inlet, outlet and filter element axes are in a straight line.

Innage
Space occupied in a product container.

Inside-mounted seal
A mechanical seal located inside the seal chamber with the pumped product’s pressure at its O.D.

Insolubles
Particles of carbon or agglomerates of carbon and other material. Indicates deposition or dispersant
drop-out in an engine. Not serious in a compressor or gearbox unless there has been a rapid increase in
these particles.

Intensifier
A device which converts low pressure fluid power into higher pressure fluid power.

Intercooler
A device which cools a gas between the compressive steps of a multiple stage compressor.

Interfacial tension (IFT)
The energy per unit area present at the boundary of two immiscible liquids. It is usually expressed in
dynes/cm (astm designation d 971.)

Ionization
The process of adding electrons to, or removing electrons from, atoms or molecules, thereby creating ions.
High temperatures, electrical discharges, and nuclear radiation can cause ionization.

IP
British Institute of Petroleum.

ISO
International Standards Organization, sets viscosity reference scales.

ISO Solid Contaminant Code (ISO 4406)
A code assigned on the basis of the number of particles per unit volume greater than 5 and 15 micrometers
in size. Range numbers identify each increment in the particle population throughout the spectrum of levels.

ISO Standard 4021
The accepted procedure for extracting samples from dynamic fluid lines.

ISO viscosity grade
A number indicating the nominal viscosity of an industrial fluid lubricant at 40 degrees C (104 degrees F)
as defined by ASTM Standard Viscosity System for Industrial Fluid Lubricants D 2422. Essentially identical
to ISO Standard 3448.

JIC
Joint industry conference

Joule
A unit of work, energy, or heat. 1J (joule)=1 Nm) (Newton meter).

Journal
That part of a shaft or axle that rotates or angularly oscillates in or against a bearing or about which a
bearing rotates or angularly oscillates.

Journal bearing
A sliding type of bearing having either rotating or oscillatory motion and in conjunction with which a journal
operates. In a full or sleeve type journal bearing, the bearing surface is 360| in extent. In a partial bearing, the
bearing surface is less than 360| in extent, i.e., 150|, 120|, etc.

Karl Fischer Reagent Method (ASTM D-1744-64)
The standard laboratory test to measure the water content of mineral base fluids. In this method, water
reacts quantitatively with the karl fischer reagent. This reagent is a mixture of iodine, sulfur dioxide, pyridine,
and methanol. When excess iodine exists, electric current can pass between two platinum electrodes or
plates. The water in the sample reacts with the iodine. When the water is no longer free to react with iodine,
an excess of iodine depolarizes the electrodes, signaling the end of the test.

kg
Kilograms

kHz
Thousand Hertz (cycles per second)

kilo
Thousand

Kinematic viscosity
The time required for a fixed amount of an oil to flow through a capillary tube under the force of gravity. The
unit of kinematic viscosity is the stoke or centistoke (1/100 of a stoke). Kinematic viscosity may be defined
as the quotient of the absolute viscosity in centipoises divided by the specific gravity of a fluid, both at the
same temperature.

km
Kilometer

Lacquer
A deposit resulting from the oxidation and polymerization of fuels and lubricants when exposed to high
temperatures. Similar to, but harder, than varnish.

Laminar particles
Particles generated in rolling element bearings which have been flattened out by a rolling contact.

Latent heat
Heat required to change the state of a unit weight of a substance from solid to liquid or from liquid to vapor
without change of temperature.

Layering
This occurs in tanks when a high density fuel is mixed with a low density fuel.

Lead naphthenate
A lead soap of naphthenic acids, the latter occurring naturally in petroleum.

LHV
Lower Heating Value

Lifting
Refers to tankers and barges taking on cargoes of oil or refined product at the terminal or transshipment
point.

Light crude
Crude oil with a low specific gravity and high API gravity due to the presence of a high proportion of light
hydrocarbon fractions and low metallic compound.

Light ends
Low-boiling volatile materials in a petroleum fraction. They are often unwanted and undesirable, but in
gasoline the proportion of light ends deliberately included are used to assist low-temperature starting.

Light obscuration
The degree of light blockage as reflected in the transmitted light impinging on the photodiode.

Lip seal
An elastomeric or metallic seal that prevents leakage in dynamic and static applications by a scraping or
wiping action at a controlled interference between itself and the mating surface.

Liquid
Any substance that flows readily or changes in response to the smallest influence. More generally, any
substance in which the force required to produce a deformation depends on the rate of deformation rather
than on the magnitude of the deformation.

Liter
A measure of capacity in the metric system equal to 61,022 cubic inches, 0.908 US quarts dry and
1.0567 US quarts wet.

Lithium grease
The most common type of grease today, based on lithium soaps.

Load-carrying capacity
Property of a lubricant to form a film on the lubricated surface, which resists rupture under given load
conditions. Expressed as maximum load the lubricated system can support without failure or excessive wear.

Load-wear index (LWI)
Measure of the relative ability of a lubricant to prevent wear under applied loads; it is calculated from data
obtained from the Four Ball EP Method. Formerly called mean Hertz load.

Log
Logarithm (common)

Long Ton
An avoirdupois weight measure equalling 2,240 pounds.

Lubricant
Any substance interposed between two surfaces in relative motion for the purpose of reducing the friction
and/or the wear between them.

Lubrication
The control of friction and wear by the introduction of a friction-reducing film between moving surfaces in
contact. The lubricant used can be a fluid, solid, or plastic substance.

Lubricator
A device which adds controlled or metered amounts of lubricant into a pneumatic system.

Lubricity
Ability of an oil or grease to lubricate; also called film strength.

LVI
Low Viscosity Index, typically below 40 VI units.

M
Meter

Magnetic
A separator that uses a magnetic field to attract and hold ferromagnetic particles.

Magnetic filter
A filter element that, in addition to its filter medium, has a magnet or magnets incorporated into its structure
to attract and hold ferromagnetic particles.

Magnetic plug
Strategically located in the flow stream to collect a representative sample of wear debris circulating in the
system: for example, engine swarf, bearing flakes, and fatigue chunks. The rate of buildup of wear debris
reflects degradation of critical surfaces.

Magnetic seal
A seal that uses magnetic material (instead of springs or a bellows) to provide the closing force that keeps
the seal faces together.

Manifold
A filter assembly containing multiple ports and integral relating components which services more than one
fluid circuit.

Manifold filter
A filter in which the inlet and outlet port axes are at right angles, and the filter element axis is parallel to either
port axis.

Marine Diesel Oil (MDO)
Marine diesel oil is a middle distillate fuel oil which can contain traces often percent (10%) or more residual
fuel oil from transportation contamination and/or heavy fuel oil blending. The MDO does not require heated
storage.

Material Safety Data Sheet (MSDS)
A publication containing health and safety information on a hazardous product (including petroleum). The
OSHA Hazard Communication Standard requires that an MSDS be provided by manufacturers to distributors
or purchasers prior to or at the time of product shipment. An MSDS must include the chemical and common
names of all ingredients that have been determined to be health hazards if they constitute 1% or greater of
the product's composition (0.1% for carcinogens). An MSDS also included precautionary guidelines and
emergency procedures.

MCR
Maximum continuous rating

MDO
Marine Diesel Oil

Media migration
Material passed into the effluent stream composed of the materials making up the filter medium.

Medium
The porous material that performs the actual process of filtration. The plural of this word is "media".

mega
Million

Metal oxides
Oxidized ferrous particles which are very old or have been recently produced by conditions of inadequate
lubrication. Trend is important.

Metalworking lubricant
Any lubricant, usually petroleum-based, that facilitates the cutting or shaping of metal. Basic types of
metalworking lubricants are: cutting and tapping fluids, drawing compounds, etc.

Metric Ton
A weight measure equal to 1,000 kilograms, 2,204.62 pounds, and 0.9842 long tons.

Mg/L
Milligrams per liter = ppm (parts per million) - expresses a measure of the concentration by weight of a
substance per unit volume.

micro
Millionth

Micron
A unit of length. One micron = 39 millionths of an inch (.000039"). Contaminant size is usually described in
microns. Relatively speaking, a grain of salt is about 60 microns and the eye can see particles to about 40
microns. Many hydraulic filters are required to be efficient in capturing a substantial percentage of contaminant
particles as small as 5 microns. A micron is also known as a micrometre, and exhibited as |m

Micron
A unit of length. One millionth of a meter or one thousandth of a millimeter. One micron equals 0.00004 of
an inch.

Microscope method
A method of particle counting which measures or sizes particles using an optical microscope.

Middle distillate
Term applied to hydrocarbons in the so-called "middle range" of refinery distillation. Examples: heating oil,
diesel fuels, and kerosene.

MIL
Military

milli
Thousandth

Mineral oil
Oil derived from a mineral source, such as petroleum, as opposed to oils derived from plants and animals.

Mineral seal oil
A distillation fraction between kerosene and gas oil, widely used as a solvent oil in gas adsorption
processes, as a lubricant for the rolling of metal foil, and as a base oil in many specialty formulations.
Mineral seal oil takes its name - not from any sealing function - but from the fact that it originally replaced
oil derived from seal blubber for use as an illuminant for signal lamps and lighthouses.

Miscible
Capable of being mixed in any concentration without separation of phases; e.g., water and ethyl alcohol are
miscible.

mm
Millimeter

Mold (release) lubricant
A compound, often of petroleum origin, for coating the interiors of molds for glass and ceramic products.
The mold lubricant facilitates removal of the molded object from the mold, protects the surface of the mold,
and reduces or eliminates the need for cleaning it.

Molecule
The smallest division of a compound that still retains or exhibits all the properties of the substance.

Moly
Molybdenum disulfide, a solid lubricant and friction reducer, colloidally dispersed in some oils and greases.

Molybdenum disulfide
A black, lustrous powder (mos2) that serves as a dry-film lubricant in certain high-temperature and high-
vacuum applications. It is also used in the form of pastes to prevent scoring when assembling press-fit parts,
and as an additive to impart residual lubrication properties to oils and greases. Molybdenum disulfide is often
called moly or molysulfide.

Motor
A device which converts fluid power into mechanical force and motion. It usually provides rotary mechanical
motion.

Motor gasoline
A complex mixture of relatively volatile hydrocarbons with or without small quantities of additives, that
have been blended to form a fuel suitable for use in spark-ignition engines.

MSDS
Material safety data sheet - a document that provides pertinent information and a profile of a particular
hazardous substance or mixture. An MSDS is normally developed by the manufacturer or formulator of the
hazardous substance or mixture. The MSDS is required to be made available to employees and operators
whenever there is the likelihood of the hazardous substance or mixture being introduced into the workplace.
Some manufacturers prepare MSDS for products that are NOT considered to be hazardous to show that the
product or substance is NOT hazardous.

MTBF
An abbreviation for Mean Time Between Failures.

Multigrade oil
An oil meeting the requirements of more than one SAE viscosity grade classification, and may therefore be
suitable for use over a wider temperature range than a single-grade oil.

Multipass or recirculation test
Filter performance tests in which the contaminated fluid is allowed to recirculate through the filter for the
duration of the test. Contaminant is usually added to the test fluid during the test. The test is used to determine
the beta-ratio (q.v.) Of an element.

Naphtha
A volatile, colorless product of petroleum distillation. Used primarily as paint solvent, cleaning fluid, and
blendstock in gasoline production, to produce motor gasoline by blending with straight-run gasoline.

Naphthenes
One of three basic hydrocarbon classifications found naturally in crude oil. Naphthenes are widely used as
petrochemical feedstock. Examples are: cyclopentane; methyl-,ethyl, and propylcyclopentane.

Naphthenic
A type of petroleum fluid derived from naphthenic crude oil, containing a high proportion of closed-ring
methylene groups.

NAS
National aerospace standard

NASA
National Aeronautics and Space Administration

NEC
National electrical code

Needle bearing
A rolling type of bearing containing rolling elements that are relatively long compared to their diameter.

NEMA
National electrical manufacturers association

Neutralization number
A measure of the total acidity or basicity of an oil; this includes organic or inorganic acids or bases or a
combination thereof (ASTM Designation D974-58T)

Newtonian fluid
A fluid with a constant viscosity at a given temperature regardless of the rate of shear. Single-grade oils are
newtonian fluids. Multigrade oils are non-newtonian fluids because viscosity varies with shear rate.

NFPA
National fluid power association

NH3N
Ammonia nitrogen.

Nitration
Nitration products are formed during the fuel combustion process in internal combustion engines. Most
nitration products are formed when an excess of oxygen is present. These products are highly acidic, form
deposits in combustion areas and rapidly accelerate oxidation.

NLGI (National Lubricating Grease Institute)
Trade association whose main interest is grease and grease technology. NLGI is best known for its system
of rating greases by penetration.

NLGI Automotive Grease Classifications
Automotive lubricating grease quality levels established jointly by SAE, ASTM and NLGI. There are several
categories in two classifications: Chassis Lubricants and Wheel bearing Lubricants. Quality or performance
levels within each category are defined by ASTM tests.

NLGI consistency grades
Simplified system established by the National Lubricating Grease Institute (NLGI) for rating the consistency
of grease.

Nominal filtration rating
An arbitrary micrometer value indicated by a filter manufacturer. Due to lack of reproducibility this rating is
deprecated.

Non-Newtonian fluid
Fluid, such as a grease or a polymer-containing oil (e.g., multi-grade oil), in which shear stress is not
proportional to shear rate.

Nonwoven medium
A filter medium composed of a mat of fibers.

Normal paraffin
A hydrocarbon consisting of molecules in which any carbon atom is attached to no more than two other
carbon atoms; also called straight chain paraffin and linear paraffin.

NPDES permit
National Pollutant Discharge Elimination System permit is the regulatory agency document issued by
either a federal or state agency which is designated to control all discharges of pollutants from point
sources into U.S. waterways. NPDES permits regulate discharges into navigable waters from all point
sources of pollution, including industries, municipal wastewater treatment plants, sanitary landfills, large
agricultural feed lots and return irrigation flows.

Obliteration
A synergistic phenomenon of both particle silting and polar adhesion. When water and silt particles
co-exist in a fluid containing long-chain molecules, the tendency for valves to undergo obliteration increases.

Oil
Crude petroleum and other hydrocarbons produced at the wellhead in liquid form.

Oil analysis
The routine activity of analyzing lubricant properties and suspended contaminants for the purpose of
monitoring and reporting timely, meaningful and accurate information on lubricant and machine condition.

Oil consumption ratio
Annual oil purchases divided by machine charge volume. For example, if you purchased 10,000 gallons
of oil in one year and the total amount of oil that all of your machine holds is 4,200 gallons, your consumption
ratio is 2.4.

Oil ring
A loose ring, the inner surface of which rides a shaft or journal and dips into a reservoir of lubricant from
which it carries the lubricant to the top of a bearing by its rotation with the shaft.

Oiler
A device for once-through lubrication. Three common types of oilers are: drop-feed, wick-feed, and bottle-
feed; all depend on gravity to induce a metered flow of oil to the bearing. The drop-feed oiler delivers oil from
the bottom of a reservoir to a bearing one drop at a time; flow rate is controlled by a needle valve at the top
of the reservoir. In a wick-feed oiler, the oil flows through a wick and drops from the end of the wick into the bearing; feed is regulated by chaining the number of strands, by raising or lowering the oil level, or by

applying pressure to the wick. In a bottle-feed oiler, a vacuum at the top of the jar keeps the fluid from
running out; as tiny bubbles of air enter, the vacuum is reduced and a small amount of oil enters the bearing
or is added to a reservoir from wick the bearing is lubricated.

Oiliness
That property of a lubricant that produces low friction under conditions of boundary lubrication. The lower
the friction, the greater the oiliness.

Oiliness agent
An additive, usually polar in nature, used to improve the lubricity of a mineral oil. Now usually called a
boundary lubrication additive.

Olefins
Class of unsaturated paraffin hydrocarbons recovered from petroleum. Typical examples include: butene,
ethylene and propylene.
Open bubble point (boil point)
The differential gas pressure at which gas bubbles are profusely emitted from the entire surface of a wetted
filter element under specified test conditions.

Open gear
A gear that is exposed to the environment, rather than being housed in a protective gear box. Open gears are
generally large, heavily loaded, and slow moving. They are found in such applications as mining and
construction machinery, punch presses, plastic and rubber mills, tube mills, and rotary kilns. Open gears
require viscous, adhesive lubricants that bond to the metal surfaces and resist run-off. Such lubricants are
often called gear shields. Top-quality lubricants for such applications are specially formulated to protect the
gears against the effects of water and other contaminants.

OSHA
The Williams-Steiger Occupational Safety and Health Act of 1970 (OSHA) is a law designed to protect the
health and safety of industrial workers and treatment plant operators. It regulates the design, construction,
operation and maintenance of industrial plants and wastewater treatment plants. The Act does not apply
directly to municipalities, EXCEPT in those states that have approved plans and have asserted jurisdiction
under Section 18 of the OSHA Act. Wastewater treatment plants have come under stricter regulation in all
phases of activity as a result of OSHA standards. OSHA also refers to the federal and state agencies which
administer the OSHA regulations.

Outage
Space left in a product container to allow for expansion during the temperature changes it may undergo during
shipment and application. Measurement of space that is NOT occupied in a drum.

Outside-mounted seal
A mechanical seal with its seal head mounted outside the seal chamber that holds the fluid to be sealed.
Outside seals have the pumped fluid's pressure at their I.D.

Oxidation
Occurs when oxygen attacks petroleum fluids. The process is accelerated by heat, light, metal catalysts and
the presence of water, acids, or solid contaminants. It leads to increased viscosity and deposit formation.

Oxidation inhibitor
Substance added in small quantities to a petroleum product to increase its oxidation resistance, thereby
lengthening its service or storage life; also called anti-oxidant. An oxidation inhibitor may work in one of these ways: (1) by combining with and modifying peroxides (initial oxidation products) to render them harmless,
(2) by decomposing the peroxides, or (3) by rendering an oxidation catalyst inert.

Oxidation stability
Ability of a lubricant to resist natural degradation upon contact with oxygen.

Oxidizing agent
Any substance such as oxygen and chlorine , that can accept electrons. When oxygen or chlorine is added to
wastewater, organic substances are oxidized. These oxidized organic substances are more stable and less likely to give off odors or to contain disease bacteria.

Ozonation
The application of ozone to water, wastewater, or air, generally for the purposes of disinfection or odor control.

P
Pressure - psi

PAH
Polycyclic aromatic hydrocarbons. (occasionally polyaluminum hydroxide)

Paper chromatography
A method which involves placing a drop of fluid on a permeable piece of paper and noting the development
and nature of the halos, or rings, surrounding the drop through time. The roots of this test can be traced to
the 1940s, when railroads used the "blotter spot" tests.

Paraffin
Any hydrocarbon identified by saturated straight (normal) or branched (iso) carbon chains; also called an
alkane. The generalized paraffinic molecule can be symbolized by the formula cnh2n+2. Paraffins are
relatively non-reactive and have excellent oxidation stability. In contrast to naphthenic oils, paraffinic lubricating
oils have relatively high wax content and pour point, and generally have a high viscosity index (VI.). Paraffinic
solvents are generally lower in solvency than naphthenic or aromatic solvents.

Paraffinic
A type of petroleum fluid derived from paraffinic crude oil and containing a high proportion of straight chain
saturated hydrocarbons. Often susceptible to cold flow problems.

Parallel systems
Lubrication systems where the dispensing devices are connected to the main line in parallel. Each
dispensing device operates independent of any other in the system.

Particle count
The number of particles present greater than a particular micron size per unit volume of fluid often stated as
particles > 10 microns per milliliter.

Particle density
An important parameter in establishing an entrained particle's potential to impinge on control surfaces and
cause erosion.

Particle erosion
Occurs when fluid-entrained particles moving at high velocity pass through orifices or impinge on metering
surfaces or sharp angle turns.

Particle impingement erosion
A particulate wear process where high velocity, fluid-entrained particles are directed at target surfaces.

Particulate
Free suspended solids.

Particulates
Particles made up of a wide range of natural materials (e.g., pollen, dust, resins), combined with man-made
pollutant (e.g., smoke particles, metallic ash); in sufficient concentrations, particulates can be a respiratory
irritant.

Pascal
Unit of pressure in the metric (SI) system.

Pascal's Law
A pressure applied to a confined fluid at rest is transmitted with equal intensity throughout the liquid and that
pressure is considered to act at right angles to each surface contacted by the fluid.

Patch test
A method by which a specified volume of fluid is filtered through a membrane filter of known pore structure.
All particulate matter in excess of an "average size," determined by the membrane characteristics, is retained
on its surface. Thus, the membrane is discolored by an amount proportional to the particulate level of the fluid
sample. Visually comparing the test filter with standard patches of known contamination levels determines
acceptability for a given fluid.

PCB
Polychlorinated biphenyl, a class of synthetic chemicals consisting of a homologous series of compounds
beginning with monochlorobiphenyl and ending with decachlorobiphenyl. Pcbs do not occur naturally in
petroleum, but have been found as contaminants in used oil. Pcbs have been legally designated as a health
hazard, and any oil so contaminated bust be handled in strict accordance with state and federal regulations.

Pensky-Martens
A closed-cup test for flash points of oil.

Peristaltic pump
A type of positive displacement pump.

Permeability
The relationship of flow per unit area to differential pressure across a filter medium.

Petrochemical
Any chemical substance derived from crude oil or its products, or from natural gas. Some petrochemical
products may be identical to others produced from other raw materials such as coal and producer gas.

Petroleum
A generic name for hydrocarbons, including crude oil, natural gas liquids, natural gas and their products.

pH
Measure of alkalinity or acidity in water and water-containing fluids. Ph can be used to determine the
corrosion-inhibiting characteristic in water-based fluids. Typically, ph > 8.0 is required to inhibit corrosion of
iron and ferrous alloys in water-based fluids.

Phenol
A white, crystalline compound (C6H5OH) derived from benzene, used in the manufacture of phenolic resins,
weed killers, plastics, disinfectants; also used in solvent extraction, a petroleum refining process. Phenol is
a toxic material; skin contact must be avoided.

Phosphate ester
Any of a group of synthetic lubricants having superior fire resistance. A phosphate ester generally has poor
hydrolytic stability, poor compatibility with mineral oil, and a relatively low viscosity index (VI). It is used as
a fire-resistant hydraulic fluid in high-temperature applications.

PIB
Product Information Bulletin. General information on a product.

Pinion
The smaller of two mating or meshing gears; can be either the driving or the driven gear.

Pitting
A form of extremely localized attack characterized by holes in the metal. Pitting is one of the most destructive
and insidious forms of corrosion. Depending on the environment and the material, a pit may take months,
or even years, to become visible.

Pleated filter
A filter element whose medium consists of a series of uniform folds and has the geometric form of a
cylinder, cone, disc, plate, etc. Synonymous with "convoluted" and "corrugated".

PNA (polynuclear aromatic)
Any of numerous complex hydrocarbon compounds consisting of three or more benzene rings in a compact
molecular arrangement. Some types of PNA's are formed in fossil fuel combustion and other heat
processes, such as catalytic cracking.

Pneumatics
Engineering science pertaining to gaseous pressure and flow.

Poise (absolute viscosity)
A measure of viscosity numerically equal to the force required to move a plane surface of one square
centimeter per second when the surfaces are separated by a layer of fluid one centimeter in thickness. It
is the ratio of the shearing stress to the shear rate of a fluid and is expressed in dyne seconds per square
centimeter (dyne sec/cm2); 1 centipoise equals .01 poise.

Polar compound
A chemical compound whose molecules exhibit electrically positive characteristics at one extremity and
negative characteristics at the other. Polar compounds are used as additives in many petroleum products.
Polarity gives certain molecules a strong affinity for solid surfaces; as lubricant additives (oiliness agents),
such molecules plate out to form a tenacious, friction-reducing film. Some polar molecules are oil-soluble
at one end and water-soluble at the other end; in lubricants, they act as emulsifiers, helping to form stable
oil-water emulsions. Such lubricants are said to have good metal-wetting properties. Polar compounds
with a strong attraction for solid contaminants act as detergents in engine oils by keeping contaminants
finely dispersed.

Polishing (bore)
Excessive smoothing of the surface finish of the cylinder bore or cylinder liner in an engine to a mirror-like
appearance, resulting in depreciation of ring sealing and oil consumption performance.

Pollution
The impairment (reduction) of water quality by agriculture, domestic or industrial wastes (including thermal
and radioactive wastes) to such a degree as to hinder any beneficial use of the water or render it offensive
to the senses of sight, taste, or smell or when sufficient amounts of waste creates or poses a potential
threat to human health or the environment.

Polyglycols
Polymers of ethylene or propylene oxides used as a synthetic lubricant base. Properties include very good
hydrolytic stability, high viscosity index (VI), and low volatility. Used particularly in water emulsion fluids.

Polymer
A substance formed by the linkage (polymerization) of two or more simple, molecules, called monomers,
to form a single larger molecule having the same elements in the same proportions as the original
monomers; i.e. Each monomer retains its structural identity. A polymer may be liquid or solid; solid
polymers may consist of millions of repeated linked units. A polymer made from two or more similar
monomers is called a copolymer; a copolymer composed of three different types of monomers is a
terpolymer. Natural rubber and synthetic rubbers are examples of polymers. Polymers are commonly
used as viscosity index improvers in multi-grade oils and tackifiers in lubricating greases.

Polymerization
Process of combining two or more simple molecules of the same type, called monomers, to form a single
molecule having the same elements in the same proportion as in the original molecules, but having
increased molecular weight. The product of the combination is a polymer.

Polyol ester
A synthetic lubricant base, formed by reacting fatty acids with a polyol (such as a glycol) derived from
petroleum. Properties include good oxidation stability at high temperatures and low volatility. Used in
formulating lubricants for turbines, compressors, jet engines, and automotive engines.

Polyolefin
A polymer derived by polymerization of relatively simple olefins. Polyethylene and polyisoprene are
important polyolefins.

Pore
A small channel or opening in a filter medium which allows passage of fluid.

Pore size distribution
The ratio of the number of effective holes of a given size to the total number of effective holes per unit area
expressed as a percent and as a function of hole size.

Porosity
The ratio of pore volume to total volume of a filter medium expressed as a percent.

Positive crankcase ventilation (PCV)
System for removing blow-by gases from the crankcase and returning them through the carburetor intake
manifold to the combustion chamber where the recirculated hydrocarbons are burned. A pc valve controls
the flow of gases from the crankcase to reduce hydrocarbon emissions.

Pour point
Lowest temperature at which an oil or distillate fuel is observed to flow, when cooled under conditions
prescribed by test method ASTM D 97. The pour point is 3°C (5°F) above the temperature at which the oil in
a test vessel shows no movement when the container is held horizontally for five seconds.

Pour point depressant
An additive which retards the adverse effects of wax crystallization, and lowers the pour point.

Pour stability
The ability of a pour depressed oil to maintain its original ASTM pour point when subjected to long-term
storage at low temperature approximating winter conditions.

Power unit
A combination of pump, pump drive, reservoir, controls and conditioning components which may be
required for its application.

PPM
Parts per million (1/ppm = 0.000001). Generally by weight. 100 ppm = 0.01%; 10,000 ppm = 1%

ppm
Parts per million - the unit commonly used to designate the concentration of a substance in a wastewater
in terms of weight ie. one pound per million pounds, etc. PPM is synonymous with the more commonly
used term mg/L (milligrams per liter).

Predictive maintenance
A type of condition-based maintenance emphasizing early prediction of failure using non-destructive
techniques such as vibration analysis, thermography, and wear debris analysis.

PREFIXES - U.S. TERM

Pressure
Force per unit area, usually expressed in pounds per square inch.

Pressure drop
Resistance to flow created by the element (media) in a filter. Defined as the difference in pressure upstream
(inlet side of the filter) and downstream (outlet side of the filter).

Pressure gage
Pressure differential above or below atmospheric pressure.

Pressure line filter
A filter located in a line conducting working fluid to a working device or devices.

Pressure, absolute
The sum of atmospheric and gage pressures.

Pressure, atmospheric
Pressure exerted by the atmosphere at any specific location. (sea level pressure is approximately 14.7
pounds per square inch absolute.)

Pressure, back
The pressure encountered on the return side of a system.

Pressure, cracking
The pressure at which a pressure operated valve begins to pass fluid.

Pressure, rated
The qualified operating pressure which is recommended for a component or a system by the manufacturer.

Pressure, system
The pressure which overcomes the total resistances in a system. It includes all losses as well as
useful work.

Preventive maintenance
Maintenance performed according to a fixed schedule involving the routine repair and replacement of
machine parts and components.

Proactive Maintenance
A maintenance strategy for stabilizing the reliability of machines or equipment. Its central theme involves
directing corrective actions aimed at failure root causes, not active failure symptoms, faults, or machine wear
conditions. A typical proactive maintenance regiment involves three steps: (1) setting a quantifiable target
or standard relating to a root cause of concern (e.g., a target fluid cleanliness level for a lubricant), (2)
implementing a maintenance program to control the root cause property to within the target or standard
relating to a root cause of concern (e.g., a target fluid cleanliness level for a lubricant), (2) implementing a
maintenance program to control the root cause property to within the target level (e.g., routine exclusion or
removal of contaminants), and (3) routine monitoring of the root cause property using a measurement
technique (e.g., particle counting) to verify the current level is within the target.

Process oil
An oil that serves as a temporary or permanent component of a manufactured products. Aromatic process
oils have good solvency characteristics; their applications include proprietary chemical formulations, ink oils,
and extenders in synthetic rubbers. Naphthenic process oils are characterized by low pour points and good
solvency properties. Paraffinic process oils are characterized by low aromatic content and light color.

psi
Pounds per square inch

PSIA
Pounds per square inch absolute. (psig + 14.696)

PSID
Pounds per square inch differential.

PSIG
Pounds per square inch gauge (PSIA - 14.696)

Pump
A device which converts mechanical force and motion into hydraulic fluid power.

Pump, fixed displacement
A pump in which the displacement per cycle cannot be varied.

Pump, variable displacement
A pump in which the displacement per cycle can be varied.

Pumpability
The low temperature, low shear stress-shear rate viscosity characteristics of an oil that permit satisfactory
flow to and from the engine oil pump and subsequent lubrication of moving components.

Purifier
A machine used for a liquid-liquid separation in which the two intermixed liquids which are insoluble in
each other have different specific gravities. Solids with specific gravities higher than those of the liquids
can be separated off at the same time. A purifier bowl has two outlets; one for the light phase liquid and one
for the heavy phase liquid.

Pusher seal
A mechanical seal in which the secondary seal is pushed along the shaft or sleeve to compensate for
misalignment and face wear.

Q
Flow rate - GPM

Quenching oil
(Also called heat treating oil) a high-quality, oxidation-resistant petroleum oil used to cool metal parts during
their manufacture, and is often preferred to water because the oil's slower heat transfer lessens the
possibility of cracking or warping of the metal. A quenching oil must have excellent oxidation and thermal
stability, and should yield clean parts, essentially free of residue. In refining terms, a quenching oil is an oil
introduced into high temperature vapors of cracked (see cracking) petroleum fractions to cool them.

Quick Disconnect A coupling which can quickly join or separate a fluid line without the use of tools or special devices.

R & O - Rust-and-oxidation inhibited
A term applied to highly refined industrial lubricating oils formulated for long service in circulating lubrication
systems, compressors, hydraulic systems, bearing housing, gear boxes, etc. The finest R&O oils are often
referred to as turbine oils.

Ramsbottom coke
A carbon residue test originated by Dr. J.R. Ramsbottom in England.

Rate of shear
The difference between the velocities along the parallel faces of a fluid element divided by the distance
between the faces.

Rated flow
The maximum flow that the power supply system is capable of maintaining at a specific operating pressure.

Reagent
A pure chemical substance that is used to make new products or is used in chemical tests to measure,
detect, or examine other substances.

Recycle
The use of water or wastewater within (internally) a facility before it is discharged to a treatment system.

Reduced crude oil
Crude oil that has undergone at least one distillation process to separate some of the lighter hydrocarbons.
Reducing crude lowers its API gravity, but increases the handling safety by raising the flash point.

Reducer
A connector having a smaller line size at one end than the other.

Reducing agent
Any substance, such as the base metal (iron) or the sulfide ion that will readily donate (give up) electrons.
The opposite of an oxidizing agent.

Redwood viscosity
The number of seconds required for 50 ml. of an oil to flow out of a standard Redwood viscosimeter at a
definite temperature; British viscosity standard.

Refinery
A plan used to separate the various components present in crude oil and convert them into usable
products or feedstock for other processes.

Refining
A series of processes for converting crude oil and its fractions to finished petroleum products. Following
distillation, a petroleum fraction may undergo one or more additional steps to purify or modify it. These
refining steps include; thermal cracking, catalytic cracking, polymerization, alkylation, reforming,
hydrocracking, hydroforming, hydrogenation, hydrogen treating, hydrofining, solvent extraction, dewaxing,
deoiling, acid treating, clay filtration, and deasphalting. Refined lubricating oils may be blended with other
lube stocks, and additives may be incorporated, to impart special properties.

Refraction
The change of direction or speed of light as it passes from one medium to another.

Refrigerator oil
The lubricant added to the working fluid in an expansion-type cooling unit which serves to lubricate the
pump mechanism.

Rerefining
A process of reclaiming used lubricant oils and restoring them to a condition similar to that of virgin stocks
by filtration, clay adsorption or more elaborate methods.

Reservoir
A container for storage of liquid in a fluid power system.

Reservoir (sump) filter
A filter installed in a reservoir in series with a suction or return line.

Residual fuel oil
Heavy fuel oils produced from the non-volatile residue from the fractional distillation process. Heavy oils that
are "leftovers" from various refining processes. Heavy black oils used in marine boilers and in heating plants.

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

Return line
A location in a line conducting fluid from working device to reservoir.

Return line filtration
Filters located upstream of the reservoir but after fluid has passed through the system's output components
(cylinders, motors, etc.).

Reynold's number
A numerical ratio of the dynamic forces of mass flow to the shear stress due to viscosity. Flow usually
changes from laminar to turbulent between Reynold’s Number 2,000 and 4,000.

Rheology
The study of the deformation and flow of matter in terms of stress, strain, temperature, and time. The
rheological properties of a grease are commonly measured by penetration and apparent viscosity.

Ring lubrication
A system of lubrication in which the lubricant is supplied to the bearing by an oil ring.

Ring sticking
Freezing of a piston ring in its groove in a piston engine or reciprocating compressor due to heavy deposits
in the piston ring zone.

Rings
Circular metallic elements that ride in the grooves of a piston and provide compression sealing during
combustion. Also used to spread oil for lubrication.

Roller bearing
An antifriction bearing comprising rolling elements in the form of rollers.

Rolling oil
An oil used in hot- or cold-rolling of ferrous and non-ferrous metals to Facilitate feed of the metal between
the work rolls, improve the plastic deformation of the metal, conduct heat from the metal, and extend the life
of the work rolls. Because of the pressures involved, a rolling oil may be compounded or contain EP
additives. In hot rolling, the oil may also be emulsifieable.

Roll-off cleanliness
The fluid system contamination level at the time of release from an assembly or overhaul line. Fluid system
life can be shortened significantly by full-load operation under a high fluid contamination condition for just
a few hours. Contaminant implanted and generated during the break-in period can devastate critical
components unless removed under controlled operating and high performance filtering conditions.

Rotary seal
A mechanical seal which rotates with a shaft and is used with a stationary mating ring.

rpm
Revolutions per minute

Rust inhibitor
A type of corrosion inhibitor used in lubricants to protect surfaces against rusting.

Rust prevention test (turbine oils)
A test for determining the ability of an oil to aid in preventing the rusting of ferrous parts in the presence
of water.

SAE
Society of Automotive Engineers, an organization serving the automotive industry.

SAE port
A straight thread port used to attach tube and hose fittings. It employs an "O" ring compressed in a wedge-
shaped cavity. A standard of the Society of Automotive Engineers J514 and ANSI/B116.1

SAE viscosity
The viscosity classification of a motor oil according to the system developed by the Society of Automotive
Engineers and now in general use. "Winter" grades are defined by viscosity measurements at low
temperatures and have "W" as a suffix, while "Summer" grades are defined by viscosity at 100°C and have
no suffix. Multigrade oils meet both a winter and a summer definition and have designations such as SAE
10W-30, etc.

Sample preparation
Fluid factors that can enhance the accuracy of the particulate analysis. Such factors include particle
dispersion, particle settling, and sample dilution.

Saponification number
The number of milligrams of potassium hydroxide (KOH) that combine with one gram of oil under conditions
specified by test method ASTM D 94. Saponification number is an indication of the amount of fatty saponifiable
material in compounded oil. Caution must be used in interpreting test results if certain substances - such as
sulfur compounds or halogens - are present in the oil, since these also react with KOH, thereby increasing
the apparent Saponification number.

Saturation level
The amount of water that can dissolve in a fluid.

Saybolt furol viscosity
A viscosity test similar in nature to the Saybolt Universal viscosity test but one more appropriate for testing
high=viscosity oils. Certain transmission and gear oils, and heavy fuel oils are rated by this method. The
results obtained are approximately 1/10th the viscosity which would be shown by the Saybolt Universal
method.

Saybolt Universal Viscosity (SUV) or Saybolt Universal Seconds, (SUS)
The time in seconds required for 60 cubic centimeters of a fluid to flow through the orifice of the Standard
Saybolt Universal Viscometer at a given temperature under specified conditions. (ASTM Designation D 88.)

Scoring
Distress marks on sliding metallic surfaces in the form of long, distinct scratches in the direction of motion.
Scoring is an advanced stage of scuffing.

Scuffing
Abnormal engine wear due to localized welding and fracture. It can be prevented through the use of antiwear,
extreme-pressure and friction modifier additives.

Scuffing particles
Large twisted and discolored metallic particles resulting from adhesive wear due to complete lubricant
film breakdown.

Seal
A device designed to prevent the movement of fluid from one area to another, or to exclude contaminants.

Seal assembly
A group of parts, or a unitized assembly, that includes sealing surfaces, provisions for initial loading, and a
secondary sealing mechanism that accommodates the radial and axial movement necessary for installation
and operation.

Seal chamber
The area between the seal chamber bore and a shaft in which a mechanical seal is installed.

Seal face
It is either of the two lapped surfaces in a mechanical seal assembly forming the primary seal.

Seal face width
The radial distance from the inside edge to the outside edge of the sealing face.

Seal swell (rubber swell)
The swelling of rubber (or other elastomers) gaskets, or seals when exposed to petroleum, synthetic
lubricants, or hydraulic fluids. Seal materials vary widely in their resistance to the effect of such fluids.
Some seals are designed so that a moderate amount of swelling improves sealing action.

Semisolid
Any substance having the attributes of both a solid and a liquid. Similar to semiliquid but being more closely
related to a solid than a liquid. More generally, any substance in which the force required to produce a
deformation depends both on the magnitude and on the rate of the deformation.

Servovalve
A valve which modulates output as a function of an input command.

Severe sliding
Large ferrous particles which are produced by sliding contacts. Trend is important to determine whether
abnormal wear is taking place.

Shear rate
Rate at which adjacent layers of fluid move with respect to each other, usually expressed as reciprocal
seconds.

Shear stress
Frictional force overcome in sliding one "layer" of fluid along another, as in any fluid flow. The shear stress
of a petroleum oil or other newtonian fluid at a given temperature varies directly with shear rate (velocity).
The ratio between shear stress and shear rate is constant; this ratio is termed viscosity of a newtonian fluid,
the greater the shear stress as a function of rate of shear. In a non-newtonian fluid

Short ton
An avoirdupois measure of weight equal to 2,000 lbs.

Silt
Contaminant particles 5 |m and less in size.

Silting
A failure generally associated with a valve which movements are restricted due to small particles that
have wedged in between critical clearances (e.g., the spool and bore.)

Single-pass test
Filter performance tests in which contaminant which passes through a test filter is not allowed to
recirculate back to the test filter.

Sintered medium
A metallic or nonmetallic filter medium processed to cause diffusion bonds at all contacting points.

SIT
Spontaneous Ignition Temperature. The temperature at which an oil ignites of its own accord in the
presence of air or oxygen under standard conditions.

Slagging
Formation of hard deposits on boiler tubes and/or piston crowns, usually due to the presence of sodium,
vanadium and sulfur.

Sleeve bearing
A journal bearing, usually a full journal bearing.

Sloughing off
The release of contaminant from the upstream side of a filter element to the upstream side of the filter
enclosure.

Sludge
Deposits in fuel tanks and caused by the presence of wax, sand, scale, asphaltenes, tars, water, etc. The
"sludge" formed in a #6 fuel oil storage tank is mostly composed of heavy hydrocarbons. Alken Even-Flo® 905
eliminates this type of sludge by breaking the sludge into small particles and re-suspending them in the fuel
for more efficient combustion. The "sludge" formed in diesel storage tanks is a combination of water with
fungus and bacteria, which grow on the unevenly mixed water/fuel interface. Adding Alken Even-Flo® 910 and
910S to stored fuel promotes a clean separation of water and fuel, reducing the substrate upon which bacteria
and fungus can grow. Since the bacteria and fungus bind to the separated water, they can be removed by
draining the water from the storage tank. If draining the storage tank is impossible, EF 905 and 910E will
emulsify the water into tiny droplets and break the sludge into such small particles that they will no longer
clog filters and will efficiently burn.

Solid
Any substance having a definite shape which it does not readily relinquish. More generally, any substance
in which the force required to produce a deformation depends upon the magnitude of the deformation
rather than upon the rate of deformation.

Soluble
Matter or compounds capable of dissolving into a solution.

Solvency
Ability of a fluid to dissolve inorganic materials and polymers, which is a function of aromaticity.

Solvent
A material with a strong capability to dissolve a given substance. The most common petroleum solvents are
mineral spirits, xylene, toluene, hexane, heptane, and naphthas. Aromatic-type solvents have the highest
solvency for organic chemical materials, followed by naphthenes and paraffins. In most applications, the
solvent disappears, usually by evaporation, after it has served its purpose. The evaporation rate of a solvent
is very important in manufacture.

Solvent Extraction
A refining process used to separate components (unsaturated hydrocarbons) from lube distillates in order
to improve the oil's oxidation stability, viscosity index, and response to additives. The oil and the solvent
extraction media are mixed in an extraction tower, resulting in the formation of two phases: a heavy phase
consisting of the undesirable unsaturates dissolved in the solvent. And a lighter phase consisting of a high
quality oil with some solvent dissolved in it. The phases are separated and the solvent recovered from each
by distillation.

Spec. sheet
Specification Sheet. Detailed information of a product including, tests, color, odor, specific gravity, bacterial
strains, other major ingredients, etc.

Specific gravity
Weight of a particle, substance or chemical solution in relation to an equal volume of water at 15C.
Abbreviated as Sp.Gr.

Specific gravity (liquid)
The ratio of the weight of a given volume of liquid to the weight of an equal volume of water.

Specific heat
The quantity of heat required to raise the temperature of a unit weight of a substance by 1 degree; usually
expresses as calories/gram/C or BTU/lb./F.

Specifications
Term referring to the properties of a given crude oil or petroleum product, which are "specified" since they
often vary widely even within the same grade of product. In the normal process of negotiation, seller will
guarantee buyer that product or crude to be sold will meet certain specified limits, and will agree to have
such limits certified in writing.

Generally the major qualities of oil for which a buyer would demand a guarantee are: API gravity (or specific
gravity, in some cases), sulfur percentage measured by weight, pour point measured by degrees C
maximum, viscosity min./max., BS&W percentage by weight, etc.

Spectrographic analysis
Determines the concentration of elements represented in the entrained fluid contaminant.

Spectrographic Oil Analysis Program (SOAP)
Procedures for extracting fluid samples from operating systems and analyzing them spectrographically for
the presence of key elements.

Spindle oil
A light-bodied oil used principally for lubricating textile spindles and for light, high-speed machinery.

Spin-on filter
A throw-away type bowl and element assembly that mates with a permanently installed head.

Splash lubrication
A system of lubrication in which parts of a mechanism dip into and splash the lubricant onto themselves
and/or other parts of the mechanism.

SR1
Seconds Redwood # 1 @ 100 F

SSF
Seconds Saybolt Furol

SSU
Saybolt Universal Seconds (or SUS), a unit of measure used to indicate viscosity, e.g., SSU @ 100| F

Stabilize
To convert to a form that resists change. Organic material is stabilized by bacteria which convert the material
to gases and other relatively inert substances. Stabilized organic material generally will not give off obnoxious
odors.

Static friction
The force just sufficient to initiate relative motion between two bodies under load. The value of the static
friction at the instant relative motion begins is termed break-away friction.

Static mixer
A motionless mixer which has a series of fixed, geometric elements enclosed within a tubular housing. The
internal elements impart flow division and radial mixing to the media flowing through the housing to produce
a uniform dilution of the production.

Static seal
A seal between two surfaces which have no relative motion.

Stationary seal
A mechanical seal in which the flexible members do not rotate with the shaft.

Statistical process control (SPC)
The use of control charts to track and eliminate variables in repetitive manufacturing processes, in order to
ensure that the product is of consistent and predictable quality. If a chart reveals only chance variations that
are inherent in the system, the process is said to be in a state of "statistical control". If the chart reveals
variations traceable to changes in equipment, procedures or workers, the process is said to be "out of
control". Statistical process control differs from statistical quality control in that the former monitors
manufacturing process parameters and the latter monitors product quality parameters.

Stick-slip motion
Erratic, noisy motion characteristic of some machine ways, due to the starting friction encountered by a
machine part at each end of its back-and-form (reciprocating) movement. This undesirable effect can be
overcome with a way lubricant, which reduces starting friction.

STLE
Society of Tribologist and Lubrication Engineers, formerly ASLE, American Society of Lubrication Engineers.

Stoke (St)
Kinematic measurement of a fluid's resistance to flow defined by the ratio of the fluid's dynamic viscosity
to its density.

STP
Standard Temperature (25C) and Pressure (300 mm Mercury).

Straight mineral oil
Petroleum oil containing no additives. Straight mineral oils include such diverse products as low-cost once-
through lubricants and thoroughly refined white oils. Most high-quality lubricants, however, contain additives.

Straight oil
A mineral oil containing no additives.

Straight-run
Refers to a petroleum product produced by the primary distillation of crude oil, free of cracked components.

Strainer
A coarse filter element (pore size over approximately 40 |m)

Stratification
Occurs in blended fuels that have a compatibility problem. It is usually experienced when paraffinic based oils
are mixed with asphaltic based oils, causing asphaltenes to precipitate and settle to the bottom of the tank.

Suction filter
A pump intake-line filter in which the fluid is below atmospheric pressure.

Sulfated ash
The ash content of fresh, compounded lubricating oil as determined by ASTM Method D 874. Indicates
level of metallic additives in the oil

Sulfonate
A hydrocarbon in which a hydrogen atom has been replaced with the highly polar (SO2OX) group, where X
is a metallic ion or alkyl radical. Petroleum sulfonates are refinery by-products of the sulfuric acid treatment
of white oils. Sulfonates have important applications as emulsifiers and chemical intermediates in
petrochemical manufacture, and substituted sulfonates are widely used as corrosion inhibitors. Synthetic
sulfonates can be manufactured from special feedstocks rather than from white oil base stocks.

Sulfur
A common natural constituent of petroleum products. While certain sulfur compounds are commonly used
to improve the EP, or load-carrying, properties of an oil, high sulfur content in a petroleum product may be
undesirable as it can be corrosive and create an environmental hazard when burned. For these reasons,
sulfur limitations are specified in the quality control of fuels, solvents, etc.

Sulfurized oil
Oil to which sulfur or sulfur compounds have been added.

Superclean
10 particles >10 micron per milliliter

Surface fatigue wear
The formation of surface or subsurface cracks and fatigue crack propagation. It results from cyclic loading
of a surface.

Surface filtration
Filtration which primarily retains contaminant on the influent surface.

Surface tension
The contractile surface force of a liquid by which it tends to assume a spherical form and to present the least
possible surface. It is expressed in dynes/cm or ergs/cm2.

Surfactant
Surface-active agent that reduces interfacial tension of a liquid. A surfactant used in a petroleum oil may
increase the oil's affinity for metals and other materials.

Surge
A momentary rise of pressure in a circuit.

SUS (SSU)
Saybolt Universal Seconds. A measure of lubricating oil viscosity in the oil industry. The measuring apparatus
is filled with specific quantity of oil or other Fluid and its flow time through standatized offrice is measured in
Seconds. Fast flowing fluids (low viscosity) will have low value; Slow flowing fluids (high viscosity) will have
high value.

Swarf
The cuttings, and grinding fines that result from metal working operations.

Switch, pressure
An electric switch operated by fluid pressure.

Synthetic hydrocarbon
Oil molecule with superior oxidation quality tailored primarily out of paraffinic materials.

Synthetic lubricant
A lubricant produced by chemical synthesis rather than by extraction or refinement of petroleum to produce
a compound with planned and predictable properties.

Synthetic oils
Oils produced by synthesis (chemical reaction) rather than by extraction or refinement. Many (but not all)
synthetic oils offer immense advantages in terms of high temperature stability and low temperature fluidity,
but are more costly than mineral oils. Major advantage of all synthetic oils is their chemical uniformity.

T
Temperature change, Fahrenheit

t
Time in seconds

Tacky
A descriptive term applied to lubricating oils and greases which appear particularly sticky or adhesive.

Tag-Robinson Colorimeter
An instrument used to determine the color of oils. Also a scale of color values.

TAN
(Total) acid number

TBN
Total Base Number. ASTM D2896. This is measured in mg. KOH needed to neutralize an acidic solution
through a reverse titration. TBN is the ability of the product to neutralize acid. In a motor oil, this is a property
which allows the oil to neutralize acids from combustion that would otherwise degrade the oil.

Thermal conductivity
Measure of the ability of a solid or liquid to transfer heat.

Thermal stability
Ability of a fuel or lubricant to resist oxidation under high temperature operating conditions.

Thermal value
Calories per gram of BTU per pound produced by burning fuels.

Thermography
The use of infrared thermography whereby temperatures of a wide variety of targets can be measured
remotely and without contact. This is accomplished by measuring the infrared energy radiating from the
surface of the target and converting this measurement to an equivalent surface temperature.

Thin film lubrication
A condition of lubrication in which the film thickness of the lubricant is such that the friction between the
surfaces is determined by the properties of the surfaces as well as by the viscosity of the lubricant.

Thixotropy
That property of a lubricating grease which is manifested by a softening in consistency as a result of
shearing followed by a hardening in consistency starting immediately after the shearing is stopped.

Three-body abrasion
A particulate wear process by which particles are pressed between two sliding surfaces.

Thrust bearing
An axial-load bearing.

Timken EP test
Measure of the extreme-pressure properties of a lubricating oil. The test utilizes a Timken machine, which
consists of a stationary block pushed upward, by means of a lever arm system, against the rotating outer
race of a roller bearing, which is lubricated by the product under test. The test continues under increasing
load (pressure) until a measurable wear scar is formed on the block.

Timken OK load
The heaviest load that a test lubricant will sustain without scoring the test block in the Timken Test
procedures, ASTM Methods D 2509 (greases) and D 2782 (oils).

Topped crude oil
Oil from which the light ends have been removed by a simple refining process. Also referred to as
"reduced crude oil".

Total Acid Number (TAN)
The quantity of base, expressed in milligrams of potassium hydroxide, that is required to neutralize all acidic
constituents present in 1 gram of sample. (astm designation d 974.)

Total Base Number (TBN)
The quantity of acid, expressed in terms of the equivalent number of milligrams of potassium hydroxide
that is required to neutralize all basic constituents present in 1 gram of sample. (astm designation d 974.)

Total Existent Sediment
Combination of inorganic and hydrocarbon sediments existing in a fuel as delivered.

Toxic
A substance which is poisonous to a living organism.

Toxicity
The relative degree of being poisonous or toxic. A condition which may exist in wastes and will inhibit or
destroy the growth or function of certain organisms.

Tribology
The science and technology of interacting surfaces in relative motion, including the study of lubrication,
friction and wear. Tribological wear is wear that occurs as a result of relative motion at the surface.

Turbidity
The degree of opacity of a fluid.

Turbine oil
A top-quality rust- and oxidation-inhibited (R&O) oil that meets the rigid requirements traditionally imposed
on steam-turbine lubrication. Quality turbine oils are also distinguished by good demulsibility, a requisite
of effective oil-water separation. Turbine oils are widely used in other exacting applications for which long
service life and dependable lubrication are mandatory. Such compressors, hydraulic systems, gear drives,
and other equipment. Turbine oils can also be used as heat transfer fluids in open systems, where oxidation
stability is of primary importance.

Turbulent flow sampler
A sampler that contains a flow path in which turbulence is induced in the main stream by abruptly changing
the direction of the fluid.

Ubbehohde viscosimeter
A suspended level apparatus for accurately determining the viscosity of a liquid.

Ullage
The amount which a tank or vessel lacks of being full.

Ultraclean
1 particle >10 micron per milliliter

Unbalanced seal
A mechanical seal arrangement wherein the full hydraulic pressure of the seal chamber acts to close
the seal faces.

Unloading
The release of contaminant that was initially captured by the filter medium

V
Total volume (gals)

Vacuum separator
A separator that utilizes subatmospheric pressure to remove certain gases and liquids from another liquid
because of their difference in vapor pressure.

Valve
A device which controls fluid flow direction, pressure, or flow rate.

Valve lifter
Sometimes called a "cam follower," a component in engine designs that use a linkage system between
a cam and the valve it operates. The lifter typically translates the rotational motion of the cam to a
reciprocating linear motion in the linkage system.

Valve, by-pass
A valve whose primary function is to provide an alternate flow path.

Valve, directional control
A valve whose primary function is to direct or prevent flow through selected passages.

Valve, directional control, servo
A directional control valve which modulates flow or pressure as a function of its input signal.

Valve, flow control
A valve whose primary function is to control flow rate.

Valve, pressure control, relief
A pressure control valve whose primary function is to limit system pressure.

Valve, relief, differential pressure
A valve whose primary function is to limit differential pressure.

Vanadium inhibitor
An organic and/or inorganic metal bearing chemical intended to chemically and/or physically combine with
the compounds formed during combustion of heavy fuel oil to improve the surface properties of the treated
ash compounds.

Vapor pressure
Pressure of a confined vapor in equilibrium with its liquid at specified temperature thus, a measure of
a liquid's volatility.

Vapor Pressure-Reid (RVP)
Measure of the pressure of vapor accumulated above a sample of gasoline or other volatile fuel in a standard
bomb at 100|F (37.8|C). Used to predict the vapor locking tendencies of the fuel in a vehicle's fuel system.
Controlled by law in some areas to limit air pollution from hydrocarbon evaporation while dispensing.

Varnish
When applied to lubrication, a thin, insoluble, nonwipeable film deposit occurring on interior parts, resulting
from the oxidation and polymerization of fuels and lubricants. Can cause sticking and malfunction of close-
clearance moving parts. Similar to, but softer, than lacquer.

Vis-Breaking
A light thermal cracking process carried out on a fuel oil during the refining process to reduce product
viscosity without blending.

Viscometer or Viscosimeter
An apparatus for determining the viscosity of a fluid.

Viscosimeter
A device for determining the viscosity of oil. There are several methods or devices in general use. Basically,
a fixed quantity of oil is allowed to pass through a fixed orifice at a specified temperature over a measured
time span and then compared to a standard liquid such as a calibration oil or water.

Viscosity
Measurement of a fluid's resistance to flow. The common metric unit of absolute viscosity is the poise,
which is defined as the force in dynes required to move a surface one square centimeter in area past a
parallel surface at a speed of one centimeter per second, with the surfaces separated by a fluid film one
centimeter thick. In addition to kinematic viscosity, there are other methods for determining viscosity,
including saybolt universal viscosity (suv), saybolt furol viscosity, engier viscosity, and redwood viscosity.
Since viscosity varies in inversely with temperature, its value is meaningless until the temperature at which
it is determined is reported.

Viscosity grade
Any of a number of systems which characterize lubricants according to viscosity for particular applications,
such as industrial oils, gear oils, automotive engine oils, automotive gear oils, and aircraft piston engine oils.

Viscosity index (VI)
A commonly used measure of a fluid's change of viscosity with temperature. The higher the viscosity index,
the smaller the relative change in viscosity with temperature.

Viscosity index improvers
Additives that increase the viscosity of the fluid throughout its useful temperature range. Such additives are
polymers that possess thickening power as a result of their high molecular weight and are necessary for
formulation of multi-grade engine oils.

Viscosity modifier
Lubricant additive, usually a high molecular weight polymer, that reduces the tendency of an oil's viscosity
to change with temperature.

Viscosity, absolute
The ration of the shearing stress to the shear rate of a fluid. It is usually expressed in centipoise.

Viscosity, kinematic
The absolute viscosity divided by the density of the fluid. It is usually expressed in centistokes.

Viscosity, SUS
Saybolt Universal Seconds (SUS), which is the time in seconds for 60 milliliters of oil to flow through a
standard orifice at a given temperature. (ASTM Designation D88-56.)

Viscosity-temperature relationship
The manner in which the viscosity of a given fluid varies inversely with temperature. Because of the
mathematical relationship that exists between these two variables, it is possible to predict graphically the
viscosity of a petroleum fluid at any temperature within a limited range if the viscosities at two other
temperatures are known. The charts used for this purpose are the ASTM Standard Viscosity-Temperature
Charts for liquid Petroleum Products, available in 6 ranges. If two know viscosity-temperature points of a fluid
are located on the chart and a straight line drawn through them, other viscosity-temperature values of the fluid
will fall on this line; however, values near or below the cloud point of the oil may deviate from the straight-line
relationship.

Viscous
Possessing viscosity. Frequently used to imply high viscosity.

Volatile
A volatile substance is one that is capable of being evaporated or changed to a vapor at a relatively low
temperature. Volatile substances also can be partially removed by air stripping.

Volatility
This property describes the degree and rate at which a liquid will vaporize under given conditions of
temperature and pressure. When liquid stability changes, this property is often reduced in value.

Water-Glycol fluid
A fluid whose major constituents are water and one or more glycols or polyglycols.

Way
Longitudinal surface that guides the reciprocal movement of a machine part.

Way lubricant
Lubricant for the sliding ways of machine tools such as planers, grinders, horizontal boring machines,
shapers, jig borers, and milling machines. A good way lubricant is formulated with special frictional
characteristics designed to overcome the stick-slip motion associated with slow-moving machine parts.

Wear
The attrition or rubbing away of the surface of a material as a result of mechanical action.

Wear debris
Particles that are detached from machine surfaces as a result of wear and corrosion. Also known as
wear particles.

Wear inhibitor
An additive which protects the rubbing surfaces against wear, particularly from scuffing, if the hydrodynamic
film is ruptured.

Weld point
The lowest applied load in kilograms at which the rotating ball in the Four Ball EP test either seizes and
welds to the three stationary balls, or at which extreme scoring of the three balls results.

Wicking
The vertical absorption of a liquid into a porous material by capillary forces.

Work penetration
The penetration of a sample of lubricating grease immediately after it has been brought to 77F and then
subjected to 60 stokes in a standard grease worker. This procedure and the standard grease worker are
described in ASTM Method D 217.

ZDDP
An antiwear additive found in many types of hydraulic and lubricating fluids. Zinc dialkyldithiophosphate.