Related Terms


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 boundary 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.


Oil derived from a mineral source, such as petroleum.


A liquid mineral oil which has a color range from slightly yellow to black derived from liquid and solid hydrocarbons found naturally in the earth's strata and which can be refined into products ranging from asphalt, waxes, naphtha, kerosene, diesel, jet fuel, gasoline, solvents, chemicals, and natural gases.


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.


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


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.


The residue left after treating petroleum oil with sulfuric acid for the removal of impurities.


Engineering concerned with the discovery, development, and exploitation of coal, ores, and minerals, as well as the cleaning, sizing, and dressing of the product. Also known as mineral engineering.


A unit of pressure, equal to the pressure exerted by a column of mercury 1 millimeter high with a density of 13.5951 grams per cubic centimeter under the standard acceleration of gravity; equal to 133.322387415 pascals; it differs from the torr at the bottom used for hauling bulk materials. mineral engineering See mining engineering.


A measure of the concentration of dissolved mineral substances in water.

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