ASTM D4175 Terminology Relating to Petroleum, Petroleum Products, and Lubricants
P - in electromagnetics, symbol for radiant power.
particle sizing, v - segregation of granular material into specified particle size ranges.
particulate, adj - of or relating to minute separate particles.

DISCUSSION - Solids generally composed of oxides, silicates, and fuel insoluble salts.

particulate solids - may enter a fuel from the air (suspended dirt and aerosols) or from the distribution and storage systems (rust, corrosion products, gasket debris, and so forth).
peak EGT, n - for octane rating, as the mixture is manually leaned from a state rich of stoichiometric, the exhaust gas temperature will increase with the removal of excess fuel. As the mixture is continually leaned, a peak temperature will be attained, after which continued leaning will result in lower exhaust gas temperatures.
penetration, n - of lubricating grease, the depth that the standard cone, when released to fall under its own weight for 5 s, enters the sample.
penetration, n - of a propellant or of petrolatum, the depth, in tenths of a millimetre, that a standard cone penetrates the sample under prescribed conditions of weight, time, and temperature.
penetration, n - of petroleum wax, the depth, in tenths of a millimetre, to which a standard needle penetrates into the wax under defined conditions.
penetration, n - the depths to which one material extends into or penetrates another.
penetration of petrolatum, n - the depth, in tenths of a millimetre, that a standard cone will penetrate the sample under fixed conditions of mass, time, and temperature.
penetrometer, n - an instrument that measures the consistency or hardness of semiliquid to semisolid materials by measuring the depth to which a specified cone or needle under a given force falls into the material.

DISCUSSION - In this test method, either a standard penetrometer 6.2 or an optical penetrometer cone A1.3 can be used to determine the consistency of lubricating greases. The penetrating force is determined by the mass of the cone and the shaft.

DISCUSSION - In this test method, a standard penetrometer needle (6.3) is used to determine the hardness of petroleum wax. The penetration force is determined by the total mass (100 g) of the needle, plunger, and 50 g weight.

DISCUSSION - In these test methods, either a one-quarter scale cone (A1.1) or a one-half scale cone (A1.3) can be used to determine the consistency of lubricating greases. The penetration forces are determined by the respective masses of the cones and shafts.

pentane insolubles, n - in used oil analysis, separated matter resulting when a used oil is dissolved in pentane.

DISCUSSION - In this test method, the separation is effected by centrifugation.

DISCUSSION - In this method, the separation is effected by filtration through a membrane.

DISCUSSION - In this test method, the separation is effected by paper filtration.

peptization, n - of asphaltenes in crude oils or heavy fuel oils, the dispersion of asphaltenes to produce a colloidal dispersion.
percent evaporated, n - in batch distillation, the sum of the percent recovered and the percent loss.
percent evaporated, n - the sum of the percent recovered and the percent loss.
percent loss, n - in batch distillation, 100 minus the percent total recovery.
percent loss (or observed loss), n - one hundred minus the percent total recovery.
corrected loss, n - percent loss corrected for barometric pressure.
percent recovered, n - the volume of condensate observed in the receiving cylinder, expressed as a percentage of the charge volume, associated with a simultaneous temperature reading.
percent recovery, n - the maximum percent recovered, as observed in accordance with 10.18.
corrected percent recovery, n - the percent recovery, adjusted for the difference between the observed loss and the corrected loss, as described in Eq. 8.
percent total recovery, n - the combined percent recovery and residue in the flask, as determined in accordance with 11.1.
percent residue, n - the volume of residue in the flask, measured in accordance with 10.19, and expressed as a percentage of the charge volume.
permanent shear stability index (PSSI), n - a measure of the irreversible decrease, resulting from shear, in an oil's viscosity contributed by an additive.

DISCUSSION - PSSI is a property calculated for a single component. Viscosity Loss (q.v.) is a property measured for a finished oil.

permeability, n - a property measured by the rate of passage of a fluid under a pressure gradient through a material.
permeability, n - in gas diffusion, the flow of gas, through the gas diffuser.

DISCUSSION - In this test method, the permeability is measured at a pressure of 2.45 kPa (250 mm of water) in millilitres per minute.

permeability, n - in gas diffusion, the rate of a substance that passes through a material (diffuser) under given conditions.
peroxide number, n - the milliequivalents of constituents in 1000 g of wax that will oxidize potassium iodide.
petroleum coke, n - a solid, carbonaceous residue produced by thermal decomposition of heavy petroleum fractions or cracked stocks, or both.
petroleum distillate, n - Synonym - distillate.
phase separation, n - the formation of two layers, a lower aqueous constituent and an upper hydrocarbon constituent, separated by either a common boundary or a layer of emulsion.

DISCUSSION - Test specimens having droplets clinging to the sides of the container or collected on its bottom, that are visible to the unaided eye, are considered to be phase separated.

picosiemens per metre, n - the unit of electrical conductivity is also called a conductivity unit (CU). A siemen is the SI definition of reciprocal ohm sometimes called mho.
1 pS/m = 1 x 10(-12)Ω(-1)m(-1) = 1 cu =1 picomho/m

pitting, n - on ring and pinion gears, small irregular cavities in the tooth surface, resulting from the breaking out of small areas of surface metal.
PLOQ, n - pooled limit of quantitation.
plugging, n - the restriction of a flow path due to the accumulation of material along the flow path boundaries.
polarization X-ray fluorescence, n - typically a polarization EDXRF instrument is used. In difference to direct excitation EDXRF spectrometry, polarization X-ray fluorescence uses polarized radiation for excitation. Combined with Cartesian geometry (of excitation, sample and detection system) this results in a significant improvement of the detection limit compared to direct excitation EDXRF.
polars, n - in high performance liquid chromatography, components that may contain organically bonded nitrogen, oxygen and oxidized sulfur components and are more strongly retained than aromatic hydrocarbons.

DISCUSSION - In this HPLC method, polars are backflushed with the aromatics and the two cannot be distinguished. Generally present in very small amounts, such as < 1 mass %.

pooled limit of quantitation, n - level of property or concentration of analyte above which quantitative test results can be obtained with a specified degree of confidence. See 3.2.1 for acronym.
pore, n - see void.
pore, n - in carbon and graphite technology, in a carbon or graphite foam, a passage that interconnects two cells.
pore count, n - in carbon and graphite technology, in open-cell foams, the number of pores aligned in one plane in one linear inch, as determined by stereoscopic image analysis.
porosity, n - the percentage of the total volume of a material occupied by both open and closed pores.
pour point, n - in petroleum products, the lowest temperature at which movement of the test specimen is observed under prescribed conditions of test.
power curve, n - for supercharge method knock rating, the characteristic power output, expressed as indicated mean effective pressure, over a range of fuel-air ratios from approximately 0.08 to approximately 0.12, when a supercharge test engine is operated on isooctane plus 6 ml of tetraethyllead per U.S. gallon under standard conditions at a constant intake manifold pressure of 40 in. of Hg (134.3 kPa) absolute.
preadaptation, n - the incubation of an inoculum in the presence of the test substance which is done prior to the initiation of the test and under conditions similar to the test conditions.

DISCUSSION - The aim of preadaptation is to improve the precision of the test method by decreasing variability in the rate of biodegradation produced by the inoculum. Preadaptation may mimic the natural processes which cause changes in the microbial population of the inoculum leading to more rapid biodegradation of the test substance, but it is not expected to change the final degree of biodegradation.

pre-adaptation, n - the pre-incubation of an inoculum in the presence of the test material and under conditions similar to the test conditions.

DISCUSSION - The aim of pre-adaptation is to improve the precision of the test method by decreasing variability in the rate of biodegradation produced by the inoculum. Pre-adaptation may mimic the natural processes which cause changes in the microbial population of the inoculum leading to more rapid biodegradation of the test material but not to a change in the final extent of biodegradation.

pre-adaptation, n - the incubation of an inoculum in the presence of the test material which is done prior to the initiation of the test and under conditions similar to the test conditions.
pre-column, n - a polydimethylsiloxane WCOT column used to isolate the methanol and 1-propanol and several light hydrocarbons from the higher boiling portion of the crude oil sample for transfer to the analytical column for further separation and quantification.
pre-condition, n - the pre-incubation of an inoculum under the conditions of the test in the absence of the test material.
precision, n - the closeness of agreement between test results obtained under prescribed conditions.
precision, n - the degree of agreement between two or more results on the same property of identical test material. In this practice, precision statements are framed in terms of repeatability and reproducibility of the test method.

DISCUSSION - The testing conditions represented by repeatability and reproducibility should reflect the normal extremes of variability under which the test is commonly used. Repeatability conditions are those showing the least variation; reproducibility, the usual maximum degree of variability. Refer to the definitions of each of these terms for greater detail.

precision, n - the degree of agreement between two or more results on the same property of identical test material. In this practice, precision statements are framed in terms of the repeatability and reproducibility of the test method.
preferred orientation, n - in manufactured carbon and graphite product technology, an alignment in the crystal or defect structure of a body leading to variations in physical properties as a function of direction; normally referenced to an orthogonal system where one of the axes is the working direction.
pre-flame reaction, n - in fuel testing, a slow, nonluminous reaction of the sample or its decomposition products with the atmosphere in the combustion chamber.
preignition, n - in a spark-ignition engine, ignition of the mixture of fuel and air in the combustion chamber before the passage of the spark.
pressure drop - the difference between the pressure measured in the condenser and the pressure measured in the distillation flask.

DISCUSSION - It is expressed in kilopascals (mm Hg) per metre of packed height for packed columns, or kilopascals (mm Hg) overall for real plate columns. It is higher for aromatics than for paraffins, and for higher molecular weights than for lighter molecules, at a given boilup rate.

PRF, n - primary reference fuel
primary biodegradation, n - degradation of the test material by microorganisms resulting in a change in the test material's physical or chemical properties, or both.

DISCUSSION - The extent to which the results of a primary biodegradation test correspond to the biological conversion of the test material will depend on the attribute which is being measured.

primary biodegradation, n - degradation of the test substance resulting in a change in its physical or chemical properties, or both.
primary biodegradation test, n - a test that monitors the disappearance of a test material by measuring some physical attribute of the material.

DISCUSSION - The extent to which the results of a primary biodegradation test correspond to the biological conversion of the test material will depend on the attribute which is being measured. An example of a measurement of a physical attribute is infrared (IR) measurement of the C-H bond of a methylene carbon at 2930 cm(-1) for the CEC (Coordinating European Council) biodegradation test.

primary biodegradation test, n - a test which follows the disappearance of a test substance by measuring some attribute of the substance.

DISCUSSION - The extent to which the results of a primary biodegradation test correspond to the biological conversion of the test substance will depend on the attribute which is being measured.

primary reference fuel blends above 100 octane, n - the millilitres per U.S. gallon of tetraethyllead in isooctane that define octane numbers above 100 in accordance with an empirically determined relationship.
primary reference fuel blends below 100 octane, n - the volume % of isooctane in a blend with n-heptane that defines the octane number of the blend, isooctane being assigned as 100 and n-heptane as 0 octane number.
primary reference fuels, n - for knock testing, isooctane, n-heptane, volumetrically proportioned mixtures of isooctane with n-heptane, or blends of tetraethyllead in isooctane that define the octane number scale.
primary reference fuels, n - for knock testing, volumetrically proportioned mixtures of isooctane with n-heptane, or blends of tetraethyllead in isooctane which define the supercharge rating scale.
primary reference fuels, n - for octane rating, blended fuels of reference grade isooctane and n-heptane.
proficiency testing, n - determination of a laboratory's testing capability by evaluating its test results in interlaboratory exchange testing or crosscheck programs.

DISCUSSION - One example is the ASTM D02 committee's proficiency testing programs in a wide variety of petroleum products and lubricants, many of which may involve more than a hundred laboratories.

proficiency testing, n - determination of a laboratory's testing capability by participation in an interlaboratory crosscheck program.
programmable temperature vaporizer (PTV), n - a temperature programmable injector similar to a cool-on-column injector except that the sample is injected cool into a glass liner or insert instead of the WCOT (3.1.5) column and then the temperature is programmed in a manner similar to the on-column injector.

DISCUSSION - The liner may be replaced, as necessary, to remove non-volatile materials. This injector may be operated in low split mode or direct (no splitting) mode.

propene concentrate, n - in liquefied natural gas technology, concentrate containing more than 50 % propene. (Synonym - propylene.)
propylene concentrate - concentrate containing more than 90 % propylene.
propylene concentrate, n - hydrocarbon product containing more than 50 % propylene.

DISCUSSION - Grades of propylene concentrates listed in this guide are: polymer, 99.0 % minimum propylene content; chemical, 92.0 %; and refinery, 60 %.

psig, n - pounds per square inch gage
PSSI - in viscometry, abbreviation for permanent shear stability index.
pulse travel time (Tt), n - the total time, measured in seconds, required for the sonic pulse to traverse the specimen being tested, and for the associated electronic signals to reverse the circuits of the pulse-propogation circuitry.
purchaser, n - of an ASTM test, a person or organization that pays for the conduct of an ASTM test method on a specified product.

DISCUSSION - The preferred term is purchaser. Deprecated terms that have been used are client, requester, sponsor and customer.

purge volume - the combined volume of the full analyzer sampling and conditioning systems.
pyrolytic graphite, n - in carbon and graphite technology, an artifact consisting predominantly of graphite which was deposited as a solid on a hot surface by cracking of gaseous or liquid hydrocarbons.

quality assurance, QA, n - a system of activities, the purpose of which is to provide to the producer and user of a product, measurement, or service the assurance that it meets the defined standards of quality with a stated level of confidence.

DISCUSSION - Quality assurance includes quality planning and quality control.

quality control, QC, n - a planned system of activities whose purpose is to provide a level of quality that meets the needs of users; also the uses of such a system.
quality control sample, QC sample, n - for use in quality assurance program to determine and monitor the precision and stability of a measurement system; a stable and homogenous material having physical or chemical properties, or both, similar to those of typical samples tested by the analytical measurement system. The material is properly stored to ensure sample integrity, and is available in sufficient quantity for repeated long-term testing.
quality index (QI), n - a mathematical formula that uses data from controlled parameters to calculate a value indicative of control performance.
quartz combustion tube devitrification, n - process in which samples containing alkali-metals (that is, elements from the Periodic Table Group IA, for example, sodium, potassium, etc.) or alkaline earth (that is, elements from the Periodic Table Group IIA, for example, calcium, magnesium, etc.) will cause quartz to devitrify (that is, become milky white and brittle) at elevated temperatures.

DISCUSSION - It is suggested that the quartz combustion tube temperature be kept <1200°C in order to minimize or eliminate the possibility of quartz combustion tube devitrification from occurring.

quenching oil, n - oil used for cooling metals during a heat-treating operation.