machinability, n - a measure of the ease with which a material can be shaped with the aid of cutting or abrasive tools.
manufactured carbon, n - a bonded granular carbon body whose matrix has been subjected to a temperature typically between 900 and 2400°C.
manufactured graphite, n - a bonded granular carbon body whose matrix has been subjected to a temperature typically in excess of 2400°C and whose matrix is thermally stable below that temperature.
MAP, n - manifold absolute pressure
MAT, n - manifold absolute temperature
material safety data sheet, (MSDS), n - a fact sheet summarizing information about material identification; hazardous ingredients; health, physical, and fire hazards; first aid; chemical reactivities and incompatibilities; spill, leak, and disposal procedures; and protective measures required for safe handling and storage.
maximum fill density (reduced fill density) - the volume of a container occupied by the sample, usually expressed as a percentage of the total capacity.
maximum pore diameter, n - in gas diffusion, the diameter a capillary of circular cross section which is equivalent (with respect to surface tension effects) to the largest pore of the diffuser under consideration.
DISCUSSION - The pore dimension is expressed in micrometres in this test method.
maximum pore diameter, n - in gas diffusion, the diameter of a capillary of circular cross-section which is equivalent (with respect to surface tension effects) to the largest pore of the diffuser under consideration. The pore dimension is expressed in micrometers (µm).
MEA, n - malt extract agar
mean coefficient of linear thermal expansion (CTE) - the linear thermal expansion per change in temperature; the mean coefficient of linear thermal expansion is represented by:
DISCUSSION - This has to be accompanied by the values of the two temperatures to be meaningful; the reference temperature (T0) is 20°C, and the notation may then only contain a single number, such as α200, meaning the mean coefficient of linear thermal expansion between 20 and 200°C.
mean effective pressure, n - for internal-combustion engines, the steady state pressure which, if applied to the piston during the expansion stroke is a function of the measured power.
mean square, n - in analysis of variance, a contraction of the expression "mean of the squared deviations from the appropriate average(s)" where the divisor of each sum of squares is the appropriate degrees of freedom.
measurand, n - the measurable quantity subject to measurement.
mechanical dispersion, n - a mixture produced by the application of mechanical shearing forces to a multi-phase system, one component of which is water, so as to distribute one or more of the materials uniformly throughout the mass of the water with the water existing as a continuous phase.
mechanical dispersion, n - a low energy aqueous medium produced by continuous stirring of the test solution and containing both dissolved and undissolved components of the test material.
melting point (cooling curve) of petroleum wax, n - temperature at which melted petroleum wax first shows a minimum rate of temperature change when allowed to cool under prescribed conditions.
NOTE 1 - The so-called "American Melting Point" is arbitrarily 1.65°C (3°F) above the Melting Point (Cooling Curve) of Petroleum Wax.
membrane color, n - a visual rating of particulates on a filter membrane against ASTM Color Standards.
membrane filter, n - a porous article of closely controlled pore size through which a liquid is passed to separate matter in suspension.
DISCUSSION - RR:D02-1012 contains information on membrane filters that meet the requirements therein.
membrane filter, n - a thin medium of closely controlled pore size through which a liquid is passed and on which particulate matter in suspension is retained.
metabolite, n - a chemical substance produced by any of the many complex chemical and physical processes involved in the maintenance of life.
metallic compounds - metals may be present as metallic compounds in the fuel as a natural result of the composition of the crude oil and of the refining process. However, unless special precautions are taken, additional metallic compounds can be acquired during distribution and storage. A commercial product pipeline may contain residues of lead-containing gasoline that would then be dissolved by the gas turbine fuel. Tank trucks, railroad tankcars, barges, and tankers may be inadequately cleaned and contain residues of past cargos. Acidic components in saline water salts in the fuel may react with distribution and storage equipment.
methanol, n - methyl alcohol, the chemical compound CH3OH.
methyl tertiary-butyl ether (MTBE), n - the chemical compound (CH3)3COCH3[C5H12O].
MF, n - membrane filter
microbial activity test, n - any analytical procedure designed to measure the rate or results of one or more microorganism processes.
DISCUSSION - Examples of microbial activity tests include loss or appearance of specific molecules or measuring the rate of change of parameters, such as acid number, molecular weight distribution (carbon number distribution), and specific gravity.
microbial degradation, n - (Synonym - biodegradation.)
microbial slimes - may result when conditions are conducive to the growth of microorganisms that are always present. The presence of free water is essential to the growth of many of these microorganisms that grow in tank water bottoms and feed on nutrients in the water or on the hydrocarbons.
microbially induced corrosion (MIC), n - corrosion that is enhanced by the action of microorganisms in the local environment.
micro separometer rating (MSEP), n - a numerical value indicating the ease of separating emulsified water from a sample by coalescence.
DISCUSSION - This test method uses the same instrument, Micro-Separometer, that is used in Test Method D 3948. As in Test Method D3948, the MSEP ratings are only valid within the range of 50 to 100. Ratings at the upper end of the range indicate a clean fuel with little or no contamination by surfactants. Thus a fuel with a high MSEP rating is expected to show good water-separating properties when passed through a filter-separator (coalescing-type filter) in actual service.
Micro-Separometer rating (DSEP rating), n - a numerical value indicating the ease of separating emulsified water from fuel by coalescence as affected by the presence of surface active materials (surfactants) in the fuel.
micro-separometer rating (MSEP rating), n - a numerical value indicating the ease of separating emulsified water from fuel by coalescence as affected by the presence of surface active materials (surfactants) in the fuel.
DISCUSSION - This test method uses the same instrument, Micro-Separometer, that is used in Test Method D3948. As in Test Method D3948, the MSEP ratings are only valid within the range of 50 to 100. Ratings at the upper end of the range indicate a clean fuel with little or no contamination by surfactants. Thus a fuel with a high MSEP rating is expected to show good water-separating properties when passed through a filter-separator (coalescing-type filter) in actual service.
middle distillate, n - a generic refinery/supplier term that usually denotes a fuel primarily intended for use in compression ignition/diesel engine applications, and also in non-aviation gas turbine engines and other non-automotive applications such as a burner fuel.
middle distillate, n - in the petroleum industry, a distillate whose boiling range lies between about 150°C and about 370°C (about 300°F and about 700°F).
DISCUSSION - Typical middle distillates, such as diesel fuels, kerosine, aviation turbine fuels (Jet A and Jet A-1) and home heating oils, will have flash points above 38°C (100°F). The 10 % to 90 % boiling temperatures will tend to lie between about 200°C and 350°C (about 400°F and 660°F).
DISCUSSION - The term light middle distillate has been used to indicate products like kerosine and aviation turbine fuel (Jet A and Jet A-1) that are at the lighter end of the middle distillate distillation range of about 150°C to about 300°C (about 300°F to about 570°F).
DISCUSSION - The term distillate is sometimes used to mean middle distillate. This practice is discouraged.
middle distillate fuel, n - kerosines and gas oils boiling between approximately 150°C and 400°C at normal atmospheric pressure and having a closed-cup flash point above 38°C.
miscibility, n - the ability of a reference oil and test oil to form a uniform mixture after blending and not separate into two phases after submission to a series of temperature changes.
mixed aniline point, n - the minimum equilibrium solution temperature of a mixture of two volumes of aniline (aminobenzene), one volume of sample, and one volume of n-heptane of specified purity.
mixed aniline point, n - the minimum equilibrium solution temperature of a mixture of two volumes of aniline, one volume of sample, and one volume of n-heptane of specified purity.
mixed base, adj - in lubricating grease, the description of a thickener system composed of soaps of two metals.
DISCUSSION - Although mixed-base grease can be made with soaps of more than two metals, in practice, such is rarely, if ever, encountered. All of the soaps need not be thickeners, although the major soap constituent will be one capable of forming a lubricating grease structure. Because the mixed soaps are seldom present in equal amounts. The predominant soap is referred to first.
mixed liquor, n - in sewage treatment, the contents of an aeration tank including the activated sludge mixed with primary effluent or the raw wastewater and return sludge.
mmHg, n - millimetres of mercury
mold, n - form of fungal growth, characterized by long strands of filaments (hyphae) and, under appropriate growth conditions, aerial, spore-bearing structures.
DISCUSSION - In fluids, mold colonies typically appear as soft spheres; termed fisheyes.
molded, v - formed in a closed die by the application of external pressure.
MON - in gasoline knock testing, abbreviation for Motor octane number.
monitor, n - something that reminds or warns.
DISCUSSION - A plastic holder for a membrane filter held in a field sampling apparatus.
montan wax, n - a wax-like material comprised primarily of montanic acid and its ester, higher aliphatic alcohols, and resins obtained from the solvent extraction of lignite.
motor octane number, n - for spark-ignition engine fuel, the numerical rating of knock resistance obtained by comparison of its knock intensity with that of primary reference fuels when both are tested in a standardized CFR engine operating under the conditions specified in this test method.
motor octane number of primary reference fuels above 100, n - determined in terms of the number of millilitres of tetraethyl lead in isooctane.
motor octane number of primary reference fuels from 0 to 100, n - the volume % of isooctane (equals 100.0) in a blend with n-heptane (equals 0.0).
motoring, n - for the CFR engine, operation of the CFR engine without fuel and with the ignition shut off.
MTBE - abbreviation for methyl tert-butyl ether.
µ (Greek letter Mu) - in statistics, symbol for true value.
multiple headspace extraction, n - a technique to determine the total concentration of a gas trapped in a liquid by analysis of successive gas extractions from the vapor space of a closed vessel containing a known amount of the sample.
multivariate calibration, n - a process for creating a calibration model in which multivariate mathematics is applied to correlate the absorbances measured for a set of calibration samples to reference component concentrations or property values for the set of samples.
DISCUSSION - The resultant multivariate calibration model is applied to the analysis of spectra of unknown samples to provide an estimate of the component concentration or property values for the unknown sample.
DISCUSSION - Included in the multivariate calibration algorithms are Partial Least Squares, Multilinear Regression, and Classical Least Squares Peak Fitting.
multivariate calibration, n - process for creating a model that relates component concentrations or properties to the absorbances of a set of known reference samples at more than one wavelength or frequency.
DISCUSSION - The resultant multivariate calibration model is applied to the analysis of spectra of unknown samples to provide an estimate of the component concentration or property values for the unknown sample.
DISCUSSION - The multivariate calibration algorithm employed in this test method is partial least square (PLS) as defined in Practices E 1655.