ASTM D4175 Terminology Relating to Petroleum, Petroleum Products, and Lubricants
gas, n - a fluid (such as air) that has neither independent shape nor volume but tends to expand indefinitely.
gas, n - substance (matter) in a gaseous state (see gaseous).
gaseous, adj - describing a state of matter that shows free flow, has neither a definite shape nor a definite volume, and tends to expand indefinitely unless contained.
gasoline, n - a volatile mixture of liquid hydrocarbons, generally containing small amounts of additives, suitable for use as a fuel in spark-ignition, internal combustion engines.
gasoline-alcohol blend, n - a fuel consisting primarily of gasoline along with a substantial amount (more than 0.35 mass % oxygen, or more than 0.15 mass % oxygen if methanol is the only oxygenate) of one or more alcohols.
gasoline-alcohol blend, n - a spark-ignition engine fuel consisting primarily of gasoline along with a substantial amount of one or more alcohols.
gasoline-ethanol blend, n - a fuel consisting primarily of gasoline along with a substantial amount (more than 0.35 mass % oxygen) of denatured fuel ethanol.
gasoline-ether blend, n - a fuel consisting primarily of gasoline along with a substantial amount (more than 0.35 mass % oxygen) of one or more ethers.
gasoline-ether blend, n - a spark-ignition engine fuel consisting primarily of gasoline along with a substantial amount of one or more ethers.
gasoline-oxygenate blend, n - a fuel consisting primarily of gasoline along with a substantial amount (more than 0.35 mass % oxygen, or more than 0.15 mass % oxygen if methanol is the only oxygenate) of one or more oxygenates.
gasoline-oxygenate blend, n - a spark-ignition engine fuel consisting primarily of gasoline along with a substantial amount of one or more oxygenates.
gasoline-oxygenate blend, n - spark-ignition engine fuel consisting primarily of gasoline with one or more oxygenates.
gloss retention, n - the percent of the original gloss retained by the specimen after aging under specified conditions. It is the final gloss divided by the initial gloss, multiplied by 100.
GLP - in laboratory practice, abbreviation for good laboratory practice.
glycol-base antifreeze, n - in engine coolants, ethylene or propylene glycol commonly used in admixture with water and additives to lower the coolant freezing point.
good laboratory practices (GLP), n - guidelines for the management of laboratory experiments which are published by regulatory agencies or other recognized groups and are concerned with the organizational process and the conditions under which laboratory studies are planned, performed, monitored, recorded, and reported.

DISCUSSION - The major GLPs used are USEPA-TSCA, USFDA, OECD, and to some extent the MITI version from Japan for submissions in Japan.

grade, n - the designation given a material by a manufacturer such that it is always reproduced to the same specifications established by the manufacturer.
Grade S15 B100, n - a grade of biodiesel meeting ASTM Specification D 6751 and having a sulfur specification of 15 ppm maximum.
Grade S500 B100, n - a grade of biodiesel meeting ASTM Specification D6751 and having a sulfur specification of 500 ppm maximum.
grain, n - in manufactured (synthetic) carbon and graphite, a particle of filler material (usually coke or graphite) in the starting mix formulation. Also referred to as granular material, filler particle, or aggregate material. The term is also used to describe the general texture of a carbon or graphite body, as in the descriptions listed below:
coarse grained, adj - containing grains in the starting mix that are substantially greater than 4 mm in size.
fine grained, adj - containing grains in the starting mix that are generally less than 100 µm in size.
medium grained, adj - containing grains in the starting mix that are generally less than 4 mm in size.
microfine grained, adj - containing grains in the starting mix that are generally less than 2 µm in size.
superfine grained, adj - containing grains in the starting mix that are generally less than 50 µm in size.
ultrafine grained, adj - containing grains in the starting mix that are generally less than 10 µm in size.

DISCUSSION - All of the above descriptions relate to the generally accepted practice of measuring the sizing fractions with a criterion that 90 % of the grains will pass through the stated screen size in a standard particle sizing test.

graphene layer, n - in carbon and graphite technology, a single carbon layer of the graphite structure, describing its nature by analogy to a polycyclic aromatic hydrocarbon of quasi-infinite size.

DISCUSSION - The term graphite designates a modification of the chemical element carbon in which planar sheets of carbon atoms, each atom bound to three neighbors in a honeycomb-like structure, are stacked in a three dimensional regular order. For a single layer, it is not correct to use the term graphite, which implies a three dimensional structure.

graphite, n - an allotropic crystalline form of the element carbon, occurring as a mineral, commonly consisting of a hexagonal array of carbon atoms (space group P 6(3)/mmc) but also known in a rhombohedral form (space group R 3m).
graphite, n - in carbon and graphite technology, a material consisting predominantly of the element carbon and possessing extensive long-range three-dimensional crystallographic order as determined by X-ray diffraction studies.

DISCUSSION - The presence of long-range order is usually accompanied with high electrical and thermal conductivity within the hexagonal plane. This results in a material having relatively easy machinability when compared to non-graphitic materials. The use of the term graphite without reporting confirmation of long-range crystallographic order should be avoided as it can be misleading.

graphite foam, n - in carbon and graphite technology, a porous graphite product containing regularly shaped, predominantly concave, homogeneously dispersed cells which interact to form a three-dimensional array throughout a continuum material of carbon, predominantly in the graphitic state. The final result is either an open or closed cell product.

DISCUSSION - In most foam, the cell wall thickness is less than half the average cell size.

graphitic, adj - in carbon and graphite technology, all varieties of substances consisting predominantly of the element carbon in the allotropic form of graphite irrespective of the presence of structural defects.

DISCUSSION - The use of the term graphitic is justified if three-dimensional hexagonal crystalline long-range order can be detected in the material by X-ray diffraction methods, independent of the volume fraction and the homogeneity of distribution of such crystalline domains. Otherwise, the term non-graphitic should be used.

graphitizable carbon, n - in carbon and graphite technology, a non-graphitic carbon, which, upon graphitization, converts into graphitic carbon (also known as a soft carbon).
graphitization, n - in carbon and graphite technology, a solid-state transformation of thermodynamically unstable non-graphitic carbon into graphite by thermal treatment.

DISCUSSION - The degree of graphitization is a measure of the extent of long-range 3D crystallographic order as determined by diffraction studies only. The degree of graphitization affects many properties significantly, such as thermal conductivity, electrical conductivity, strength, and stiffness.

DISCUSSION - A common, but incorrect, use of the term graphitization is to indicate a process of thermal treatment of carbon materials at T>2200°C regardless of any resultant crystallinity. The use of the term graphitization without reporting confirmation of long range three dimensional crystallographic order determined by diffraction studies should be avoided, as it can be misleading.

green carbon, n - a formed, but unfired carbon body.
green petroleum coke, n - same as raw petroleum coke.
gross heat of combustion, Qg (MJ/kg), n - the quantity of energy released when a unit mass of fuel is burned in a constant volume enclosure, with the products being gaseous, other than water that is condensed to the liquid state.

DISCUSSION - The fuel can be either liquid or solid, and contain only the elements carbon, hydrogen, nitrogen, and sulfur. The products of combustion, in oxygen, are gaseous carbon dioxide, nitrogen oxides, sulfur dioxide, and liquid water. In this procedure, 25°C is the initial temperature of the fuel and the oxygen, and the final temperature of the products of combustion.

gross heat of combustion - expressed as megajoules per kilogram. The gross heat of combustion at constant volume of a liquid or solid fuel containing only the elements carbon, hydrogen, oxygen, nitrogen, and sulfur is the quantity of heat liberated when a unit mass of the fuel is burned in oxygen in an enclosure of constant volume, the products of combustion being gaseous carbon dioxide, nitrogen, sulfur dioxide, and liquid water, with the initial temperature of the fuel and the oxygen and the final temperature of the products at 25°C. Gross heat of combustion is represented by the symbol Qg.

DISCUSSION - Users of this test method desiring to calculate ΔH° for a pure compound should note that corrections must be applied to the value of Qg for buoyancy of air, heat capacities of reaction components, reduction to a constant-pressure process, and deviations of the reaction from the thermodynamic standard state. In any comparison of measurements on pure compounds with those cited in these compilations, the user of this test method should realize that impurities of various kinds, including water and foreign hydrocarbons may cause significant effects on the values obtained for particular samples of material.

gross sample, n - a large sample made up of several portions (increments) of a mass of material.
gross sample - the original, uncrushed representative portion taken from a shipment or lot of coke.
ground, vt - to connect electrically with ground (earth).
guide, n - a series of options or instructions that do not recommend a specific course of action.

DISCUSSION - Whereas a practice describes a general usage principle, a guide only suggests an approach. The purpose of a guide is to offer guidance, based on a consensus of viewpoints, but not to establish a fixed procedure. A guide is intended to increase the awareness of the user to available techniques in a given subject area and to provide information from which subsequent evaluation and standardization can be derived.

guide tables, n - for knock testing, the specific relationship between cylinder height (compression ratio) and octane number at standard knock intensity for specific primary reference fuel blends tested at standard or other specified barometric pressure.