Copy of `Lubrication and Oil Analysis Dictionary`

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Lubrication and Oil Analysis Dictionary
Category: General technical and industrial > Oil terms
Date & country: 25/09/2008, US
Words: 423


Patch test
a method by which a specified volume of fluid is filtered through a membrane filter of known pore structure. All particulate matter in excess of an 'average size,' determined by the membrane characteristics, is retained on its surface. Thus, the membrane is discolored by an amount proportional to the particulate level of the fluid sample. Visually comparing the test filter with standard patches ...

PCB
Polychlorinated biphenyl, a class of synthetic chemicals consisting of a homologous series of compounds beginning with monochlorobiphenyl and ending with decachlorobiphenyl. PCBs do not occur naturally in petroleum, but have been found as contaminants in used oil. PCBs have been legally designated as a health hazard, and any oil so contaminated bust be handled in strict accordance with state and f...

Permeability
the relationship of flow per unit area to differential pressure across a filter medium.

Petrochemical
Any chemical substance derived from crude oil or its products, or from natural gas. Some petrochemical products may be identical to others produced from other raw materials such as coal and producer gas.

pH
measure of alkalinity or acidity in water and water-containing fluids. pH can be used to determine the corrosion-inhibiting characteristic in water-based fluids. Typically, pH > 8.0 is required to inhibit corrosion of iron and ferrous alloys in water-based fluids.

Phenol
A white, crystalline compound (C6H5OH) derived from benzene, used in the manufacture of phenolic resins, weed killers, plastics, disinfectants; also used in solvent extraction, a petroleum refining process. Phenol is a toxic material; skin contact must be avoided.

Phosphate ester
Any of a group of synthetic lubricants having superior fire resistance. A phosphate ester generally has poor hydrolytic stability, poor compatibility with mineral oil, and a relatively low viscosity index (VI). It is used as a fire-resistant hydraulic fluid in high-temperature applications.

Pinion
the smaller of two mating or meshing gears; can be either the driving or the driven gear.

Pitting
a form of extremely localized attack characterized by holes in the metal. Pitting is one of the most destructive and insidious forms of corrosion. Depending on the environment and the material, a pit may take months, or even years, to become visible.

Pleated filter
a filter element whose medium consists of a series of uniform folds and has the geometric form of a cylinder, cone, disc, plate, etc. Synonymous with 'convoluted' and 'corrugated'.

PNA
Any of numerous complex hydrocarbon compounds consisting of three or more benzene rings in a compact molecular arrangement. Some types of PNA`s are formed in fossil fuel combustion and other heat processes, such as catalytic cracking.

Pneumatics
engineering science pertaining to gaseous pressure and flow.

Poise (absolute viscosity)
a measure of viscosity numerically equal to the force required to move a plane surface of one square centimeter per second when the surfaces are separated by a layer of fluid one centimeter in thickness. It is the ratio of the shearing stress to the shear rate of a fluid and is expressed in dyne seconds per square centimeter (DYNE SEC/CM2); 1 centipoise equals .01 poise.

Q
flow rate - GPM

Quenching oil
(Also called heat treating oil) a high-quality, oxidation-resistant petroleum oil used to cool metal parts during their manufacture, and is often preferred to water because the oil`s slower heat transfer lessens the possibility of cracking or warping of the metal. A quenching oil must have excellent oxidation and thermal stability, and should yield clean parts, essentially free of residue. In refi...

Quick Disconnect
A coupling which can quickly join or separate a fluid line without the use of tools or special devices.

R & O
- Rust-and-oxidation inhibited - A term applied to highly refined industrial lubricating oils formulated for long service in circulating lubrication systems, compressors, hydraulic systems, bearing housing, gear boxes, etc. The finest R&O oils are often referred to as turbine oils.

Rate of shear
the difference between the velocities along the parallel faces of a fluid element divided by the distance between the faces.

Rated Flow
The maximum flow that the power supply system is capable of maintaining at a specific operating pressure.

Reducer
a connector having a smaller line size at one end than the other.

Refining
A series of processes for converting crude oil and its fractions to finished petroleum products. Following distillation, a petroleum fraction may undergo one or more additional steps to purify or modify it. These refining steps include; thermal cracking, catalytic cracking, polymerization, alkylation, reforming, hydrocracking, hydroforming, hydrogenation, hydrogen treating, hydrofining, solvent ex...

Refraction
the change of direction or speed of light as it passes from one medium to another.

Refrigerator oil
The lubricant added to the working fluid in an expansion-type cooling unit which serves to lubricate the pump mechanism.

Rerefining
a process of reclaiming used lubricant oils and restoring them to a condition similar to that of virgin stocks by filtration, clay adsorption or more elaborate methods.

Reservoir
a container for storage of liquid in a fluid power system.

Reservoir filter
a filter installed in a reservoir in series with a suction or return line.

Residual dirt capacity
the dirt capacity remaining in a service loaded filter element after use, but before cleaning, measured under the same conditions as the dirt capacity of a new filter element.

Return line
a location in a line conducting fluid from working device to reservoir.

Return Line Filtration
filters located upstream of the reservoir but after fluid has passed through the system's output components (cylinders, motors, etc.).

Reynold`s number
A numerical ratio of the dynamic forces of mass flow to the shear stress due to viscosity. Flow usually changes from laminar to turbulent between Reynold`s Number 2,000 and 4,000.

Rheology
The study of the deformation and flow of matter in terms of stress, strain, temperature, and time. The rheological properties of a grease are commonly measured by penetration and apparent viscosity.

Ring lubrication
a system of lubrication in which the lubricant is supplied to the bearing by an oil ring.

Ring sticking
freezing of a piston ring in its groove in a piston engine or reciprocating compressor due to heavy deposits in the piston ring zone.

Rings
circular metallic elements that ride in the grooves of a piston and provide compression sealing during combustion. Also used to spread oil for lubrication.

Roll-off cleanliness
the fluid system contamination level at the time of release from an assembly or overhaul line. Fluid system life can be shortened significantly by full-load operation under a high fluid contamination condition for just a few hours. Contaminant implanted and generated during the break-in period can devastate critical components unless removed under controlled operating and high performance filterin...

Roller bearing
an antifriction bearing comprising rolling elements in the form of rollers.

Rolling oil
An oil used in hot- or cold-rolling of ferrous and non-ferrous metals to Facilitate feed of the metal between the work rolls, improve the plastic deformation of the metal, conduct heat from the metal, and extend the life of the work rolls. Because of the pressures involved, a rolling oil may be compounded or contain EP additives. In hot rolling, the oil may also be emulsifieable.

Rotary seal
A mechanical seal which rotates with a shaft and is used with a stationary mating ring.

rpm
revolutions per minute

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

Rust prevention test
a test for determining the ability of an oil to aid in preventing the rusting of ferrous parts in the presence of water

SAE
Society of Automotive Engineers, an organization serving the automotive industry.

SAE port
A straight thread port used to attach tube and hose fittings. It employs an “O” ring compressed in a wedge-shaped cavity. A standard of the Society of Automotive Engineers J514 and ANSI/B116.1

SAE viscosity
The viscosity classification of a motor oil according to the system developed by the Society of Automotive Engineers and now in general use. “Winter” grades are defined by viscosity measurements at low temperatures and have “W” as a suffix, while “Summer” grades are defined by viscosity at 100ํํํํํํํ°ํ C and have no suffix. Multigrade oils meet both ...

Sample preparation
fluid factors that can enhance the accuracy of the particulate analysis. Such factors include particle dispersion, particle settling, and sample dilution.

Saponification number
The number of milligrams of potassium hydroxide (KOH) that combine with one gram of oil under conditions specified by test method ASTM D 94. Saponification number is an indication of the amount of fatty saponifiable material in compounded oil. Caution must be used in interpreting test results if certain substances - such as sulfur compounds or halogens - are present in the oil, since these also re...

Saturation level
the amount of water that can dissolve in a fluid.

Saybolt Universal Viscosity
the time in seconds required for 60 cubic centimeters of a fluid to flow through the orifice of the Standard Saybolt Universal Viscometer at a given temperature under specified conditions. (ASTM Designation D 88.)

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.

Scuffing
abnormal engine wear due to localized welding and fracture. It can be prevented through the use of antiwear, extreme-pressure and friction modifier additives.

Scuffing particles
large twisted and discolored metallic particles resulting from adhesive wear due to complete lubricant film breakdown.

Seal
A device designed to prevent the movement of fluid from one area to another, or to exclude contaminants.

Seal assembly
A group of parts, or a unitized assembly, that includes sealing surfaces, provisions for initial loading, and a secondary sealing mechanism that accommodates the radial and axial movement necessary for installation and operation.

Seal chamber
The area between the seal chamber bore and a shaft in which a mechanical seal is installed.

Seal face
It is either of the two lapped surfaces in a mechanical seal assembly forming the primary seal.

Seal face width
The radial distance from the inside edge to the outside edge of the sealing face.

Seal Swell
The swelling of rubber (or other elastomers) gaskets, or seals when exposed to petroleum, synthetic lubricants, or hydraulic fluids. Seal materials vary widely in their resistance to the effect of such fluids. Some seals are designed so that a moderate amount of swelling improves sealing action.

Semisolid
any substance having the attributes of both a solid and a liquid. Similar to semiliquid but being more closely related to a solid than a liquid. More generally, any substance in which the force required to produce a deformation depends both on the magnitude and on the rate of the deformation.

Servovalve
A valve which modulates output as a function of an input command.

Severe sliding
Large ferrous particles which are produced by sliding contacts. Trend is important to determine whether abnormal wear is taking place.

Shear rate
rate at which adjacent layers of fluid move with respect to each other, usually expressed as reciprocal seconds.

Shear stress
frictional force overcome in sliding one 'layer' of fluid along another, as in any fluid flow. The shear stress of a petroleum oil or other Newtonian fluid at a given temperature varies directly with shear rate (velocity). The ratio between shear stress and shear rate is constant; this ratio is termed viscosity of a Newtonian fluid, the greater the shear stress as a function of rate of shear. In...

Silt
contaminant particles 5 ¦m and less in size.

Silting
a failure generally associated with a valve which movements are restricted due to small particles that have wedged in between critical clearances (e.g., the spool and bore.)

Single-pass test
filter performance tests in which contaminant which passes through a test filter is not allowed to recirculate back to the test filter.

Sintered medium
a metallic or nonmetallic filter medium processed to cause diffusion bonds at all contacting points

t
time in seconds

T
temperature change, Fahrenheit

Tacky
A descriptive term applied to lubricating oils and greases which appear particularly sticky or adhesive.

TAN
(Total) acid number

TBN
(Total) base number

Thermal conductivity
measure of the ability of a solid or liquid to transfer heat.

Thermal stability
ability of a fuel or lubricant to resist oxidation under high temperature operating conditions.

Thermography
the use of infrared thermography whereby temperatures of a wide variety of targets can be measured remotely and without contact. This is accomplished by measuring the infrared energy radiating from the surface of the target and converting this measurement to an equivalent surface temperature.

Thin film lubrication
a condition of lubrication in which the film thickness of the lubricant is such that the friction between the surfaces is determined by the properties of the surfaces as well as by the viscosity of the lubricant.

Thixotropy
that property of a lubricating grease which is manifested by a softening in consistency as a result of shearing followed by a hardening in consistency starting immediately after the shearing is stopped.

Three-body abrasion
a particulate wear process by which particles are pressed between two sliding surfaces.

Thrust Bearing
an axial-load bearing.

Timken EP Test
Measure of the extreme-pressure properties of a lubricating oil. The test utilizes a Timken machine, which consists of a stationary block pushed upward, by means of a lever arm system, against the rotating outer race of a roller bearing, which is lubricated by the product under test. The test continues under increasing load (pressure) until a measurable wear scar is formed on the block.

Timken OK Load
the heaviest load that a test lubricant will sustain without scoring the test block in the Timken Test procedures, ASTM Methods D 2509 (greases) and D 2782 (oils).

Total Acid Number
the quantity of base, expressed in milligrams of potassium hydroxide, that is required to neutralize all acidic constituents present in 1 gram of sample. (ASTM Designation D 974.)

Total Base Number
the quantity of acid, expressed in terms of the equivalent number of milligrams of potassium hydroxide that is required to neutralize all basic constituents present in 1 gram of sample. (ASTM Designation D 974.)

Tribology
the science and technology of interacting surfaces in relative motion, including the study of lubrication, friction and wear. Tribological wear is wear that occurs as a result of relative motion at the surface.

Turbidity
the degree of opacity of a fluid.

Turbine oil
A top-quality rust- and oxidation-inhibited (R&O) oil that meets the rigid requirements traditionally imposed on steam-turbine lubrication. Quality turbine oils are also distinguished by good demulsibility, a requisite of effective oil-water separation. Turbine oils are widely used in other exacting applications for which long service life and dependable lubrication are mandatory. Such compressors...

Turbulent flow sampler
a sampler that contains a flow path in which turbulence is induced in the main stream by abruptly changing the direction of the fluid.

Ultraclean
1 particle >10 micron per milliliter

Unbalanced seal
A mechanical seal arrangement wherein the full hydraulic pressure of the seal chamber acts to close the seal faces.

Unloading
the release of contaminant that was initially captured by the filter medium.

V
total volume (gals)

Vacuum separator
a separator that utilizes subatmospheric pressure to remove certain gases and liquids from another liquid because of their difference in vapor pressure.

Valve
a device which controls fluid flow direction, pressure, or flow rate.

Valve lifter
sometimes called a 'cam follower,' a component in engine designs that use a linkage system between a cam and the valve it operates. The lifter typically translates the rotational motion of the cam to a reciprocating linear motion in the linkage system.

Valve, by-pass
a valve whose primary function is to provide an alternate flow path.

Valve, directional control
a valve whose primary function is to direct or prevent flow through selected passages.

Valve, directional control, servo
a directional control valve which modulates flow or pressure as a function of its input signal.

Valve, flow control
a valve whose primary function is to control flow rate.

Valve, pressure control, relief
a pressure control valve whose primary function is to limit system pressure.

Vapor pressure
pressure of a confined vapor in equilibrium with its liquid at specified temperature thus, a measure of a liquid's volatility.

Vapor Pressure-Reid
measure of the pressure of vapor accumulated above a sample of gasoline or other volatile fuel in a standard bomb at 100¦F (37.8¦C). Used to predict the vapor locking tendencies of the fuel in a vehicle's fuel system. Controlled by law in some areas to limit air pollution from hydrocarbon evaporation while dispensing.