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API -- American Petroleum Institute - a trade association of petroleum producers, refiners,
marketers, and transporters, organized for the furtherment of the petroleum industry.
API engine service categories -- gasoline and diesel engine oil quality levels
established jointly by API, SAE, and ASTM, and sometimes called SAE or API/SAE
categories; formerly called API Engine Service Classifications.
API gravity -- a gravity scale established by the American Petroleum Institute
and in general use in the petroleum industry, the unit being called "the
A.P.I. degree." This unit is defined in terms of specific gravity as follows:
141.5 131.5
SG SG=Specific gravity @ 60° F/60° F
Apparent viscosity -- the observed viscosity of a non-Newtonian fluid (viscosity changes with shear rate) measured at a specific shear rate and temperature.
Ash -- a measure of the amount of inorganic material in lubricating oil. Determined
by burning the oil and weighing the residue. Results expressed as percent by
weight.
Ash content -- a measure of the amount of inorganic material in lubricating oil.
Determined by burning the oil and weighing the residue. Results expressed as percent by
weight.
Indication of the amount of detergent in the oil.
Asperities -- microscopic projections on metal surfaces resulting from normal
surface-finishing processes. Interference between opposing asperities in sliding
or rolling applications is a source of friction, and can lead to metal welding
and scoring. Ideally, the lubricating film between two moving surfaces should
be thicker than the combined height of the opposing asperities.
A.S.T.M. = American Society for Testing Materials -an organization
whose purpose is to promote the knowledge of the materials of engineering and standardize
specifications and testing.
Atomic absorption spectroscopy (AA) -- measures the radiation absorbed by chemically
unbound atoms by analyzing the transmitted energy relative to the incident energy
at each frequency. The procedure consists of diluting the fluid sample with
methyl isobutyl ketone (MIBK) and directly aspirating the solution. The actual
process of atomization involves reducing the solution to a fine spray, dissolving
it, and finally vaporizing it with a flame. The vaporization of the metal particles
depends upon their time in the flame, the flame temperature, and the composition
of the flame gas. The spectrum occurs because atoms in the vapor state can absorb
radiation at certain well-defined characteristic wave lengths. The wave length
bands absorbed are very narrow and differ for each element. In addition, the
absorption of radiant energy by electronic transitions from ground to excited
state is essentially and absolute measure of the number of atoms in the flame
and is, therefore, the concentration of the element in a sample.
Atomic emission spectroscopy (AE) -- this method uses flame excitation; atoms
are excited from the heat of the flame to emit light. This method commonly uses a total
consumption burner with a round burning outlet. A higher temperature flame than atomic
absorption spectroscopy (AA) is typically used to produce excitation of analyte atoms. Since
the heat of the flame excites analyte atoms, no special elemental lamps to shine into the flame
are needed. A high resolution polychromator can be used to produce an emission intensity vs
. wavelength spectrum over a range of wavelengths showing multiple element excitation lines,
meaning multiple elements can be detected in one run. Alternatively, a monochromator can
be set at one wavelength to concentrate on analysis of a single element at a certain emission line.
Automatic transmission fluid (ATF) -- a functional fluid for automatic transmissions
in motor vehicles. Automatic transmission fluids must have suitable coefficient of friction, good low
temperature viscosity, and antiwear properties. Other necessary properties are: high oxidation
stability, anti-corrosion, anti-foaming, and compatibility with synthetic rubber seals.
Axial-load bearing -- a bearing in which the load acts in the direction of
the axis of rotation.
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