Lubricants Glossary 1

Question 1

Abrasion

Answer 1

A general wearing away of a surface by constant scratching, usually due to the presence of foreign matter such as dirt, grit, or metallic particles in the lubricant. It may also cause a break down of the material (such as the tooth surfaces of gears). Lack of proper lubrication may result in abrasion.

Question 2

Abrasive Wear

Answer 2

(Or cutting wear) Comes about when hard surface asperities or hard particles that have embedded themselves into a soft surface and plough grooves into the opposing harder surface, e.g., a journal.

Question 3

Absolute Filtration Rating

Answer 3

The diameter of the largest hard spherical particle that will pass through a filter under specified test conditions. This is an indication of the largest opening in the filter elements.

Question 4

Absolute Pressure

Answer 4

The sum of atmospheric and gage pressure

Question 5

Absolute Viscosity

Answer 5

A term used interchangeably with viscosity to distinguish it from either kinematic viscosity or commercial viscosity. Absolute viscosity is the ratio of shear stress to shear rate. It is a fluid’s internal resistance to flow. The common unit of absolute viscosity is the poise. Absolute viscosity divided by fluid density equals kinematic viscosity. It is occasionally referred to as dynamic viscosity. Absolute viscosity and kinematic viscosity are expressed in fundamental units. Commercial viscosity such as Saybolt viscosity is expressed in arbitrary units of time, usually seconds.

Question 6

Absorbent Filter

Answer 6

A filter medium that holds contaminant by mechanical means

Question 7

Absorption

Answer 7

The assimilation of one material into another; in petroleum refining, the use of an absorptive liquid to selectively remove components from a process stream.

Question 8

AC Fine Test Dust (ACFTD)

Answer 8

A test contaminant used to assess both filters and the contaminant sensitivity of all types of tribological mechanisms.

Question 9

Accumulator

Answer 9

A container in which fluid is stored under pressure as a source of fluid power.

Question 10

Acid

Answer 10

In a restricted sense, any substance containing hydrogen in combination with a nonmetal or nonmetallic radical and capable of producing hydrogen ions in solution.

Question 11

Acid Number

Answer 11

The quantity of base, expressed in milligrams of potassium hydroxide, that is required to neutralize the acidic constituents in 1 g of sample.

Question 12

Acid Sludge

Answer 12

The residue left after treating petroleum oil with sulfuric acid for the removal of impurities. It is a black, viscous substance containing the spent acid and impurities.

Question 13

Acid Treating

Answer 13

A refining process in which unfinished petroleum products, such as gasoline, kerosene, and lubricating oil stocks, are contacted with sulfuric acid to improve their color, odor, and other properties

Question 14

Acidity

Answer 14

In lubricants, acidity denotes the presence of acid-type constituents whose concentration is usually defined in terms of total acid number. The constituents vary in nature and may or may not markedly influence the behavior of the lubricant.

Question 15

Activated Alumina

Answer 15

A highly porous material produced from dehydroxylated aluminium hydroxide. Is used as a desiccant and as a filtering medium.

Question 16

Actuator

Answer 16

A device used to convert fluid energy into mechanical motion.

Question 17

Additive

Answer 17

A chemical substance added to a petroleum product to impart or improve certain properties. Common petroleum product additives are: antifoam agent, anti-wear additive, corrosion inhibitor, demulsifier, detergent, dispersant, emulsifier, EP additive, oiliness agent, oxidation inhibitor, pour point depressant, rust inhibitor, tackiness agent, viscosity index (VI.) improver.

Question 18

Additive Level

Answer 18

The total percentage of all additives in an oil. (Expressed in % of mass (weight) or % of volume)

Question 19

Additive stability

Answer 19

The ability of additives in the fluid to resist changes in their performance during storage or use.

Question 20

Adhesion

Answer 20

The property of a lubricant that causes it to cling or adhere to a solid surface.

Question 21

Adhesive Wear

Answer 21

Is often referred to as galling, scuffing, scoring, or seizing. It happens when sliding surfaces contact one another, causing fragments to be pulled from one surface and to adhere to the other.

Question 22

Adsorbent Filter

Answer 22

A filter medium primarily intended to hold soluble and insoluble contaminants on its surface by molecular adhesion.

Question 23

Adsorption

Answer 23

Adhesion of the molecules of gases, liquids, or dissolved substances to a solid surface, resulting in relatively high concentration of the molecules at the place of contact; e.g. the plating out of an anti-wear additive on metal surfaces.

Question 24

Adsorptive Filtration

Answer 24

The attraction to, and retention of particles in, a filter medium by electrostatic forces, or by molecular attraction between the particles and the medium.

Question 25

Aeration

Answer 25

The state of air being suspended in a liquid such as a lubricant or hydraulic fluid.

Question 26

Agglomeration

Answer 26

The potential of the system for particle attraction and adhesion.

Question 27

AGMA

Answer 27

An acronym for “American Gear Manufacturers Associations,” an organization serving the gear industry.

Question 28

AGMA Lubricant Numbers

Answer 28

AGMA specification covering gear lubricants. The viscosity ranges of the AGMA numbers (or grades) conform to the International Standards Organization (ISO) viscosity classification system (see ISO viscosity classification system).

Question 29

Air Bleeder

Answer 29

A device for removal of air from a hydraulic fluid line.

Question 30

Air Breather

Answer 30

A device permitting air movement between the atmosphere and the component in/on which it is installed.

Question 31

Air Entrainment

Answer 31

The incorporation of air in the form of bubbles as a dispersed phase in the bulk liquid. Air may be entrained in a liquid through mechanical means and/or by release of dissolved air due to a sudden change in environment. The presence of entrained air is usually readily apparent from the appearance of the liquid (i.e., bubbly, opaque, etc.) while dissolved air can only be determined by analysts.

Question 32

Air Motor

Answer 32

A device that converts compressed gas into mechanical force and motion. It usually provides rotary mechanical motion.

Question 33

Air/Oil Systems

Answer 33

A lubrication system in which small measured quantities of oil are introduced into an air/oil mixing device which is connected to a lube line that terminates at a bearing, or other lubrication point. The air velocity transports the oil along the interior walls of the lube line to the point of application. These systems provide positive air pressure within the bearing housing to prevent the ingress of contaminants, provide cooling airflow to the bearing, and perform the lubrication function with a continuous flow of minute amounts of oil.

Question 34

Air-Gap Solenoid

Answer 34

A solenoid that is sealed to prevent leakage of the liquid in the plunger cavity

Question 35

Alkali

Answer 35

Any substance having basic (as opposed to acidic) properties. In a restricted sense, it is applied to the hydroxides of ammonium, lithium, potassium, and sodium. Alkaline materials in lubricating oils neutralize acids to prevent acidic and corrosive wear in internal combustion engines.