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Demulsibility – The ability of a non-water-miscible fluid to separate from water with which it may be mixed. The higher the demulsibility rating, the more rapidly the fluid separates from water. Demulsibility is sometimes expressed as the rate, in cubic centimeters per hour, or settling our of a fluid from an emulsion under specified conditions. See Steam Emulsion Number.
Density – The mass of a unit volume of a substance. Its numerical value varies with the units used.
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 re-disperse deposits already formed.
Dewaxing – Process which removes wax from a lube distillate by solvent means (physical separation) or catalytic means (conversion).
Dielectric Strength – A measure of the ability of an insulating fluid to withstand the electric stress (voltage) without failure. Fluids with high dielectric strength (usually expressed in volts or kilovolts) are good electrical insulators.
Dispersing – In lubrication, usually used interchangeably with detergent. An additive which keeps fine particles of insoluble materials in a homogeneous solution. Hence, particles are not permitted to settle out and accumulate.
Distillate – A term applied to a liquid collected when condensing distilled vapors such as naphtha, kerosene, fuel oil and light lubricating oils.
Drop Feed Lubrication – A system of lubrication in which the lubricant is applied to the bearing surfaces in the form of drops at regular intervals.
Dropping Point of Grease – The temperature at which a grease passes form a semi-solid to a liquid state under specified test conditions.
Dynamic Viscosity – See Absolute Viscosity.
