ASTM D4175 Terminology Relating to Petroleum, Petroleum Products, and Lubricants
1. Scope
1.1 This terminology standard covers the compilation of terminology developed by Committee D02 on Petroleum Products and Lubricants, except that it does not include terms/definitions specific only to the standards in which they appear.
1.1.1 The terminology, mostly definitions, is unique to petroleum, petroleum products, and lubricants. Meanings of the same terms outside of applications to petroleum, petroleum products, and lubricants can be found in other compilations and in dictionaries of general usage.

1.1.2 The terms/definitions exist in two places: (1) in the standards in which they appear and (2) in this compilation.

2. Terminology
2.1 Alphabetical listing of terms with definitions for each term showing attributions as to source and subcommittee jurisdiction is in bold print following the definition. Those showing no attributes are under the jurisdiction of Subcommittee CS 95. Some abbreviations, acronyms and symbols are included in the list.
3-MPA, n - 3-methylphenylamine
abrasion, n - wear by displacement of material caused by hard particles or hard protuberances.
abrasive wear - wear due to hard particles or hard protuberances forced against and moving along a solid surface.
absolute filtration rating, n - 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 element.
absorbance, A, n - the molecular property of a substance that determines its ability to take up radiant power, expressed by:
A = log10 (1/T) = -log10T
where T is the transmittance.

DISCUSSION - Absorbance expresses the excess absorption over that of a specified reference or standard. It is implied that compensation has been affected for reflectance losses, solvent absorption losses, and refractive effects, if present, and that attenuation by scattering is small compared with attenuation by absorption.

absorptivity, a, n - the specific property of a substance to absorb radiant power per unit sample concentration and path length, expressed by:
a = Af/bc
where:
A = the absorbance,
f = the dilution factor,
b = sample cell path length, and
c = the quantity of absorbing substance contained in a volume of solvent.

acceptance limit (AL), n - a numerical value that defines the point between acceptable and unacceptable quality.

DISCUSSION - The AL is not necessarily the specification limit. It is the value that takes into account the specification value, the test method precision, and the confidence level desired for defining minimum acceptable quality relative to the specification value.

accepted reference value, n - a value that serves as an agreed-upon reference for comparison and that is derived as (1) a theoretical or established value, based on scientific principles, (2) an assigned value, based on experimental work of some national or international organization, such as the U.S. National Institute of Standards and Technology (NIST), or (3) a consensus value, based on collaborative experimental work under the auspices of a scientific or engineering group.

DISCUSSION - In the context of this test method, accepted reference value is understood to apply to the Research octane number of specific reference materials determined empirically under reproducibility conditions by the National Exchange Group or another recognized exchange testing organization.

DISCUSSION - In the context of this method, accepted reference value is understood to apply to the ignition delay of specific reference materials determined under reproducibility conditions by collaborative experimental work.

DISCUSSION - In the context of this test method, accepted reference value is understood to apply to the Supercharge and octane number ratings of specific reference materials determined empirically under reproducibility conditions by the National Exchange Group or another recognized exchange testing organization.

accuracy, n - the closeness of agreement between a test result and an accepted reference value.
accuracy, n - the closeness of agreement between an observed value and an accepted reference value.
acid number, n - the quantity of base, expressed as milligrams of potassium hydroxide per gram of sample, required to titrate a sample in a specified solvent to a specified end point.

DISCUSSION - This test method expresses the quantity of base as milligrams of potassium hydroxide per gram of sample, that is required to titrate a sample in a mixture of toluene and propan-2-ol to which a small amount of water has been added from its initial meter reading in millivolts to a meter reading in millivolts corresponding to an aqueous basic buffer solution or a well-defined inflection point as specified in the test method.

DISCUSSION - This test method provides additional information. The quantity of base, expressed as milligrams of potassium hydroxide per gram of sample, required to titrate a sample in the solvent from its initial meter reading in millivolts to a meter reading in millivolts corresponding to a freshly prepared aqueous acidic buffer solution or a well-defined inflection point as specified in the test method shall be reported as the strong acid number.

DISCUSSION - The causes and effects of the so-called strong acids and the causes and effects of the other acids can be very significantly different. Therefore, the user of this test method shall differentiate and report the two, when they are found.

acid number, n - the quantity of base, expressed in milligrams of potassium hydroxide per gram of sample that is required to titrate a sample to a specified end point.

DISCUSSION - In this test method, the indicator is p-naphtholbenzein titrated to a green/green-brown end point in a toluene-water-isopropanol solvent.

DISCUSSION - In this test method, the acid number is calculated from the number of drops required to produce a change in solution color from blue-green to orange, compared to the number of drops required to produce an identical color change using a reference standard. Because this is a direct comparison method, the acid number value can be reported in milligrams of potassium hydroxide per gram of sample.

acid number, n - the quantity of base, expressed in milligrams of potassium hydroxide per gram of sample, that is required to titrate a sample dissolved in a specified solvent to a specified end point.

DISCUSSION - In this test method, acids or salts with dissociation constants greater than 10(-9), are titrated to a green end point with p-naphtholbenzein indicator.

acid number, n - quantity of base, expressed in milligrams of potassium hydroxide per gram of sample that is required to titrate a sample in a specific solvent to a specific end point.

DISCUSSION - in this test method, the solvent is a toluene-water-isopropanol mixture and the end point is determined when a green/green brown color is obtained using the specified p-naphtholbenzein indicator solution.

acid number, n - the quantity of base, expressed as milligrams of potassium hydroxide per gram of sample, required to titrate a sample in a specified solvent to a specified end point.

DISCUSSION - This test method expresses the quantity of base as milligrams of potassium hydroxide per gram of sample, that is required to titrate a sample in a mixture of toluene and propan-2-ol to which a small amount of water has been added from its initial meter reading in millivolts to a meter reading in millivolts corresponding to an aqueous basic buffer solution or a well-defined inflection point as specified in the test method.

DISCUSSION - This test method provides additional information. The quantity of base, expressed as milligrams of potassium hydroxide per gram of sample, required to titrate a sample in the solvent from its initial meter reading in millivolts to a meter reading in millivolts corresponding to a freshly prepared aqueous acidic buffer solution or a well-defined inflection point as specified in the test method shall be reported as the strong acid number.

DISCUSSION - The causes and effects of the so-called strong acids and the causes and effects of the other acids can be very significantly different. Therefore, the user of this test method shall differentiate and report the two, when they are found.

acidity, n - the quality, state or degree of being acid.

DISCUSSION - In this test method, the criterion for acidity is a pink or red color when methyl orange indicator is used.

across (or against) grain, n - the direction in a body with preferred orientation due to forming stresses that has the maximum c-axis alignment as measured in an X-ray diffraction test.
activated sludge, n - the precipitated solid matter, consisting mainly of bacteria and other aquatic microorganisms, that is produced in a domestic wastewater treatment plant; activated sludge is used primarily in secondary sewage treatment to microbially oxidized dissolved organic matter in the effluent.
acute ecotoxicity, n - the propensity of a material to produce adverse behavioral, biochemical, or physiological effects in non-human organisms or populations in a short period of time, usually not constituting a substantial portion of the life span of the organism.
acute ecotoxicity, n - the propensity of a test material to produce adverse behavioral, biochemical or physiological effects in non-human organisms or populations in a short period, usually not constituting a substantial portion of the life span.
acute ecotoxicity test, n - a comparative ecotoxicity test in which a representative subpopulation of organisms is exposed to different treat rates of a test material and is observed for a short period, usually not constituting a substantial portion of their life span.
acute toxicity test, n - a comparative toxicity test in which a representative subpopulation of organisms is exposed to different treat rates of a test material and is observed for a short period usually not constituting a substantial portion of their life span.
additive, n - a material added to another, usually in small amounts, to impart or enhance desirable properties or to suppress undesirable properties.
adhesive wear (scuffing), n - wear due to localized bonding between contacting solid surfaces leading to material transfer between the two surfaces or loss from either surface.
adiabaticity, n - the condition in which there is no significant gain or loss of heat throughout the length of the column.

DISCUSSION - When distilling a mixture of compounds as is the case of crude petroleum, there will be a normal increase in reflux ratio down the column. In the case where heat losses occur in the column, the internal reflux is abnormally greater than the reflux in the head. The opposite is true when the column gains heat, as with an overheated mantle.

aerobe, n - an organism that requires oxygen to remain metabolically active.

DISCUSSION - Aerobes use oxygen as their terminal electron acceptor in their primary energy-generating metabolic pathways. Aerobes require oxygen for survival, using aerobic metabolic processes to generate energy for growth and survival.
aerobic, adj - (1) taking place in the presence of oxygen; (2) living or active in the presence of oxygen.
AET - abbreviation for atmospheric equivalent temperature.
agglomerate, n - in manufactured carbon and graphite product technology, a composite particle containing a number of grains.
aggressiveness index (A.I.), n - the value computed from the sum of the pH + log alkalinity + log hardness of water sample where both alkalinity and hardness are reported as CaCO3L.

DISCUSSION - As A.I. decreases, water becomes more corrosive. At A.I. ≥ 12, water is noncorrosive. At 10 ≤ A.I. < 12, water is moderately corrosive. At A.I. < 10, water is strongly corrosive.

air-fuel ratio, n - in internal combustion engines, the mass ratio of air-to-fuel in the mixture being induced into the combustion chambers.

DISCUSSION - In this test method, air-fuel ratio (AFR), is controlled by the EEC IV engine control module.

amine number of reference fuels above 100, AN - determined in terms of the weight percent of 3-methylphenylamine in reference grade isooctane (2,2,4-trimethylpentane).Forexample,5% of 3-methylphenylamine in reference grade isooctane has an amine number if 105 (AN 105). No attempt has been made to correlate performance number of leaded reference fuels to the amine number of unleaded reference fuels, and none is implied.
ampule, n - a glass vessel for the storage of liquid materials, possessing a long narrow neck for the purpose of providing a flame-sealed closure.
AN, n - amine number
anaerobe, n - an organism that cannot grow or proliferate in the presence of oxygen.

DISCUSSION - Anaerobes use molecules other than oxygen in their primary energy-generating metabolic pathways, such as sulfate, nitrate, ketones, and other high-energy organic molecules. Although anaerobes may survive in the presence of oxygen, anaerobic growth typically occurs only in an oxygen depleted environment.

anaerobic, adj - (1) taking place in the absence of oxygen; (2) living or active in the absence of oxygen.
analysis cycle time, n - the period of time required to properly obtain and analyze a representative sample of the process stream material.
analysis sample - the reduced and divided representative portion of the bulk sample, prepared for use in the laboratory.
analysis of variance (ANOVA), n - a procedure for dividing the total variation of a set of data into two or more parts, one of which estimates the error due to selecting and testing specimens and the other part(s) possible sources of added variation.
analytical column, n - a CP-Lowox wall coated open tubular (WCOT) column containing an oxygenates-selective gas chromatographic liquid phase, used to further separate methanol and 1-propanol for quantification.
analyzer lag, n - Deprecated term. Use the preferred term instrument response time.
aniline point, n - the minimum equilibrium solution temperature for equal volumes of aniline (aminobenzene) and sample.
aniline point, n - the minimum equilibrium solution temperature for equal volumes of aniline and sample.
anistropic nuclear graphite, n - graphite in which the isotropy ratio based on the value of the coefficient of thermal expansion (25-500°C) is greater than 1.15.
ANOVA, n - in statistics, acronym for analysis of variance.
anoxic, adj - oxygen free.
anti-knock index, n - the arithmetic average of the Research octane number (RON) and Motor octane number (MON).
antiknock index, n - the arithmetic average of the Research octane number (RON) and Motor octane number (MON), that is, (RON + MON)/2.
antimicrobial, n - see biocide.
API - abbreviation for American Petroleum Institute.
API gravity, n - a special function of relative density (specific gravity) 60/60°F (15.56/15.56°C), represented by: API gravity, deg = (141.5/sp gr 60/60°F) - 131.5

DISCUSSION - No statement of reference temperature is required, since 60°F is included in the definition.

apparent viscosity, n - of a lubricating grease, the ratio of shear stress to shear rate calculated from Poiseuille's equation, and is measured in poises (see 10.1).
apparent viscosity, n - the determined viscosity obtained by use of this test method.
area slice, n - area under a chromatogram within a specified retention time interval.
aromatics, n - in high performance liquid chromatography, aromatic hydrocarbon components, minus polar material, that has a longer retention time than saturates on the specified polar columns, but can be removed as a single peak by backflushing the columns with heptane.

DISCUSSION - Generally, aromatic hydrocarbons contain 1 to 4 rings.

aromatics fraction, n - portion of the sample desorbed with the polar eluants. The aromatics fraction is divided into nonpolar and polar based. They may contain aromatics, condensed naphthenic-aromatics, aromatic olefins, and compounds containing sulfur, nitrogen, and oxygen atoms.
aseptic, adj - sterile, free from viable microbiological contamination.
ash, n - in carbon and graphite technology, the residue remaining after oxidation of a carbon or graphite.
asphalt, n - a dark brown-to-black cementitious material in which the predominating constituents are bitumens.

DISCUSSION - Asphalt can be a natural product or a material obtained from petroleum processing.

asphalt, n - in North American usage, (1) the heavy, black, viscous hydrocarbon-based material used for roofing and paving or (2) mixtures of that material with aggregate or (3) finished paving.

DISCUSSION - Asphalt free of aggregate is of three types: (1) natural asphalt, (2) asphalt from the processing of crude oils, and (3) asphalt that has been modified by blowing with air or other means. Natural asphalt is obtained from tar pits or tar lakes, such as those in Trinidad. In the refinery, asphalt is usually the residual portion of asphaltic crude oil obtained as bottoms from vacuum distillation or by propane deasphalting. Either of these types of asphalt can be air blown for further removal of lighter fractions and for mild oxidation, to modify the properties of the final product.

asphaltene, n - in petroleum technology, a molecule of high molecular mass, high carbon/hydrogen ratio, and containing heteroatoms.

DISCUSSION - Asphaltenes are found largely in crude oils and in heavy fuel oils containing residual fractions. They are insoluble in alkanes such as n-heptane and cetane, but soluble in aromatic solvents such as benzene, toluene, and 1-methylnaphthalene.

asphaltenes, n - wax-free organic material insoluble in heptane, but soluble in hot toluene (benzene).

DISCUSSION - Benzene is included in this definition solely on the basis of its classical references in the definition of asphaltenes. The precision of this test method when using toluene has been found to be the same as when using benzene.

assignable cause, n - a factor that contributes to variation and that is feasible to detect and identify.
assigned test value (ATV), n - the average of all results obtained in the several laboratories which are considered acceptable based on the reproducibility of the test method.
ASTM color, n - the name of an empirical scale of expressing of the color of a petroleum liquid darker than Saybolt color based on a scale of 0.5 (lightest) to 8.0 Dil (darkest) and determined by Test Method D 1500.
ASTM color, n - an empirical definition of the color of a petroleum liquid based on a scale of 0.5 to 8 as determined by Test Method D 1500.
ASTM supercharge octane number of a fuel below 100, n - the whole number nearest the percentage by volume of isooctane (equals 100) in a blend with n-heptane (equals 0) that matches the knock characteristics of the fuel when compared by this test method.
ASTM supercharge rating of a fuel above 100, n - the amount of tetraethyllead (TEL) in isooctane, expressed in millilitres per U.S. gallon.
ATV - in statistics, abbreviation for assigned test value.
audit, n - a systematic examination of a laboratory's quality system procedure and related activities by an internal or external team to determine whether these procedures or activities are implemented according to the documented system.
autoignition, n - the ignition of a material caused by the application of pressure, heat, or radiation, rather than by an external ignition source, such as a spark, flame, or incandescent surface.
autoignition temperature, n - the minimum temperature at which autoignition occurs.
automotive, adj - descriptive of equipment associated with self-propelled machinery, usually vehicles driven by internal combustion engines.
automotive wheel bearing grease, n - a lubricating grease specifically formulated to lubricate automotive wheel bearings at relatively high grease temperatures and bearing speeds.
aviation gasoline, n - gasoline possessing specific properties suitable for fueling aircraft powered by reciprocating spark ignition engines.

DISCUSSION - Principal properties include volatility limits, stability, detonation-free performance in the engine for which it is intended and suitability for low temperature performance.