GLOSSARY OF COMMON TERMS

A / B / C / D / E / F / G / H / I / J / K / L / M / N / O / P / Q / R / S / T / U / V / W / X / Y / Z

A

Absolute Viscosity

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 the fluid’s density equals kinematic viscosity.

Additivies

Organic or inorganic compounds dissolved or suspended as solids in oil.

Antifoam Agent

An additive, commonly silicone oil, used to break up large surface bubbles or control foam.

Anti-wear

Additives that are used to protect against wear and the loss of metal surfaces during mixed-film and boundary-film lubrication.

Asperities

Microscopic projections on metal surfaces resulting from normal surface finishing processes. Ideally the lubricating film should be thicker than the combined height of the opposing asperities.

ASTM

An organization devoted to the promotion of knowledge of the materials of engineering, and the standardization of specifications and methods of testing. A preponderance of the data used to describe, identify, or specify petroleum products is determined in accordance with ASTM test methods.

B

Base Number

The number of milligrams of acid required to neutralize one gram of an oil sample.

Base Oil

All lubricants contain a base oil. It serves as the foundation of the lubricant before it is blended with additives or a thickener in the case of a grease.

Base Stock

A single product, usually defined by its viscosity grade. A mixture of one or more base stocks in a finished lubricant is a base oil.

Bleeding

Separation of a liquid from lubricating grease.

C

Cativation

Occurs when a fluid's operational pressure drops below it's vapor pressure causing gas pockets and bubbles to form and collapse.

Cloud Point

The temperature at which a lubricant appears hazy due to wax formation when a sample is cooled under standard conditions.

Compounded Oil

A mixture of petroleum oil with animal or vegetable fat or oil. Compounded oils have a strong affinity for metal surfaces; they are particularly suitable for wet-steam conditions and for applications where lubricity and extra load-carrying ability are needed. They are not generally recommended where long-term oxidation stability is required.

Conventional Oil

Conventional oil and gas refers to petroleum, or crude oil, and raw natural gas extracted from the ground by conventional means and methods.

Coolant

Fights deposits and scale in industrial cooling systems while providing long service intervals for reduced maintenance.

Corrosion

The decay and loss of a metal due to a chemical reaction between the metal and its environment.

Corrosion Inhibitor

Chemical substances that, when added in small amounts to the environment in which a metal would corrode, will reduce, slow down or prevent corrosion of the metal.

D

Demulsibility

The oil's ability to release water.

Dispersant

An additive that helps prevent deposits by holding the insoluable products of oil oxidation.

Dropping Point

The temperature at which grease passes from a semi-solid to a liquid state, as specified under ASTM D556.

E

EP Additive

A lubricant additive that prevents sliding metal surfaces from seizing under conditions of extreme pressure (EP).

Ester

A chemical compound usually derived from the reaction of an organic or inorganic acid with an alcohol.

F

Ferrography

A method of particle analysis using precision magnets to strip iron-laden and other susceptible particles from a used lubricating oil for study.

Fire Point

The temperature rating at which a lubricant will catch fire.

Film Strength

Property of a lubricant that acts to prevent scuffing or scoring of metal parts.

Flash Point

The flash point is the lowest temperature at which the vapor above the oil sample will momentarily ignite or flash when an ignition source is passed over it.

Fluid Analysis

Preventive maintenance tool designed to evaluate lubricant condition, component wear and contamination in industrial and fleet applications.

Foam

A collection of small bubbles of air that accumulate on or near the surface of the fluid.

Food Grade Lubricants

Lubricants acceptable for use in meat, poultry and other food processing equipment, applications and plants.

Fretting

A form of attritive wear resulting from small-amplitude oscillations or vibrations that cause the removal of very finely divided particles from rubbing surfaces.

G

H

High Viscosity

Measurement of the resistance to flow. Thicker oils with a high viscosity flow more slowly and perform best in heat versus cold temperatures.

Hydraulic Oil

An energy transfer or power transmission medium, lubricant, and sealant that cools the equipment and carries contaniments away.

Hydrolytic Stability

The ability of a lubricant to resist chemical decomposition (hydrolysis) in the presence of water.

Hydrophilic

Compounds that attact and bond to water.

Hydrophobic

Compounds that repel water.

I

Immiscible

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.

Inhibitor

An additive that improves the performance of a petroleum product through the control of undesirable chemical reactions.

Insulating Fluids

Also referred to as Transformer Oil, is an oil that is stable at high temperatures and has excellent electrical insulating properties. It is typically used in transformers, high-voltage capacitors, high-voltage switches and circuit breakers, and more.

ISO Viscosity Classification System

International Organization for Standardization’s (ISO) system for classifying industrial lubricants according to viscosity.

J

K

Kinematic Viscosity

A measure of a fluid's internal resistance to flow under gravitational forces. Found by taking the absolute viscosity of a liquid divided by its density at the same temperature.

L

Lacquer

A deposit resulting from the oxidation and polymerization of fuels and lubricants when exposed to high temperatures. Similar to, but harder than varnish.

Low Viscosity

Measurement of the oil's resistance to flow. Low viscosity oils are thinner and perform better in cold temperatures that higher viscosity oils.

Lubrication

The control of friction and wear by the introduction of a friction-reducing film between moving surfaces in contact.

Lubricity

The ability of an oil or grease to lubricate (also called film strength). Lubricity can be enhanced by additive treatment.

M

Micropitting

A form of fatigue failure that occurs on a material's surface, typically seen in rolling gears and bearings and causes the surface to appear grey stained.

Mineral Oil Lubricant

Mineral Oil Lubricants use base oils that are obtained as a by-product from refining crude oil.

Miscible

Capable of being mixed in any concentration without separation of phases (e.g., water and ethyl alcohol are miscible).

N

NLGI (National Lubricating Grease Institute)

Trade association whose main interest is grease and grease technology. NLGI is best known for its system of rating greases by penetration.

NLGI consistency Grades

Simplified system established by the National Lubricating Grease Institute (NLGI) for rating the consistency of grease.

O

Oil Flushing

A fluid circulation process that is designed to remove contamination and decomposition from a lubrication-based system.

Oil Sampling

A procedure which involves the collection of a volume of fluid from lubricated or hydraulic machinery for the purpose of performing oil analysis.

Oxidation

An undesirable series of chemical reactions in oil that degrades its quality and value. Occurs when oxygen attached lubricant fluids.

Oxidation Inhibitor

Also known as an anti-oxidant, an additive that is added to base oil to increase oxidation resistance.

P

PAG Synthetic Fluid

A type of base oil called polyalkylene glycol. They are classified in the Group V synthetic bases oils category.

PAO Synthetic Fluid

A type of base oil called Polyalphaolefins. They are classified in the Group IV synthetic base oils category

Particulate

A very small particle, as of dust or soot. Particulates can form in oil and result in premeture engine/machine failure.

Poise

A unit of measurement of absolute (or dynamic) viscosity.

Polyol Ester

A type of base oil called ester. They are classified in the Group V synthetic base oils category.

Pour Point

The lowest temperature at which an oil is observed to flow by gravity in a specified lab test. Minimum temperature oil has to pour down from a breaker.

Q

R

R&O

A lubricating oil with Rust and Oxidation additives added to the base oil.

Rust Inhibitor

A type of corrosion inhibitor used in lubricants to protect the lubricated surfaces against rusting.

S

Saturation Level

The amount of water that can disolve in a liquid at a given temperature.

Scoring

Distress marks on sliding metallic surfaces in the form of long, distinct scratches in the direction of motion. Scoring is an advanced stage of scuffing.

Semisynthetic

A lubricant consisting of a blend of conventional mineral oil and a synthetic hydrocarbon.

Shear Rate

The rate at which permanent shearing or viscosity loss occurs.

Solvent

A material with a strong capability to dissolve a given substance.

Stationary Engine

An internal combustion engine used to drive immobile equipment, such as pumps, generators, mills or factory machinery.

Steam Turbine

A mechanical device that extracts thermal energy from pressurized steam. The energy is converted into a rotary motion that drives a device.

Synthetic Oil

Made with products that are chemically manufactured, primarily polyalphaolefins (PAO) and esters. The chemical processes permit tight control of the molecular structure of PAOs and esters, giving the final product uniform and stable properties.

T

Thermal Stability

The ability to resist chemical degradation at high temperatures.

Tribology

The science and technology of interacting surfaces in relative motion, including the study of lubrication, friction and wear.

Total acid number (TAN)

A measurement of acidity that is determined by the amount of potassium hydroxide in milligrams that is needed to neutralize the acids in one gram of oil.

Total Base Number (TBN)

A measurement of basicity that is expressed in terms of the number of milligrams of potassium hydroxide per gram of oil sample (mg KOH/g).

Turbine Oil

A high-quality rust-and oxidation-inhibited (R&O) oil that meets the rigid requirements traditionally imposed on steam-turbine lubrication.

U

Uncompounded Oil

Straight mineral oil

V

Varnish

Thin, insoluble film deposit that forms on fluid-wetted surfaces inside a turbine or hydraulic lube system, including bearings and servo valves.

Viscosity

Oil's resistance to flow at a given temperature.

Viscosity Index

The change in an oil’s viscosity due to a temperature change. A higher number means the lubricant changes viscosity at a lower rate based on the temperature.

Volatility

The quality of changing easily into a gas: The higher the vapor pressure of a liquid at a given temperature, the higher the volatility.

W

Wear

The attrition or rubbing away of the surface of a material as a result of mechanical action.

X

Y

Z

Zinc

Commonly used name for zinc dialkyl dithiophosphate or zinc dithiophosphate, an anti-wear/oxidation inhibitor chemical used as an additive.

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