WHAT WE DO

Glossary of Terms

C or cent.: centigrade

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.

Carbon: a non-metallic element - No. 6 in the periodic table. Diamonds and graphite are pure forms of carbon. Carbon is a 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.

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.

Catalyst: a substance that initiates or increases the rate of a chemical reaction, without itself being used up in the process.

Catastrophic failure: sudden, unexpected failure of a machine resulting in considerable cost and downtime.

Caustic: A highly alkaline substance such as sodium hydroxide.

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.

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.

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.

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.


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.

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


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 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.

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.

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; also 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.