A soft, white, non-ferrous alloy bearing material composed principally of copper, antimony, tin and lead.


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.

Ball bearing

An antifriction rolling type bearing containing rolling elements in the form of balls.


A unit of liquid volume of petroleum oils equal to 42 U.S. gallons or approximately 35 Imperial gallons.


A material, which neutralizes acids. An oil additive containing colloidally dispersed metal carbonate, used to reduce corrosive wear.

Base stock

The base fluid, usually a refined petroleum fraction or a selected synthetic material, into which additives are blended to produce finished lubricants.

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.


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.

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 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.

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.

Brookfield viscosity

Apparent viscosity in cP determined by Brookfield viscometer, which measures the torque required rotating 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.


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.

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.

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.


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 selected differential pressure across the filter element is exceeded; the valve allows all or part of the flow to bypass the filter element.