WHAT WE DO

Glossary of Terms

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 ability of a fluid that is insoluble in water to separate from water with which it may be mixed in the form of an emulsion.

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.

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.

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

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.

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.