Industry Definitions

Definitions of words and terms used in the gas processing industry.
For questions regarding incorrect/outdated entries or suggestion for adding additional terms, please contact Martin Erne

"K" value

A number that represents the ratio of gas molar fraction to liquid molar fraction.


A property which indicates whether or not two fluids can be mixed in any ratio without separation of the fluids.

AGA (American Gas Association)

A national trade association of the petroleum industry whose members are U.S. and Canadian distributors of natural, manufactured, and mixed gases. AGA provides information on sales, finances, utilization, and all phases of gas transmission and distribution.

API (American Petroleum Institute)

A national trade association of the petroleum industry which is a standardizing organization for the drilling, producing, refining, transportation, and marketing segments of the industry.

API Gravity

An arbitrary scale expressing the relative density of liquid petroleum products. The scale is calibrated in degrees API, calculated by the following formula: (141.5 / relative density) -131.5

ASTM (American Society for Testing and Materials)

A national organization which promotes knowledge of the materials of engineering and the standardization of specifications and methods of testing.

ASTM distillation

Any distillation made in accordance with an ASTM procedure. Generally it refers to a distillation test to determine the initial boiling point, the temperature at which percentage fractionations of the sample are distilled, the final boiling point, and the quantity of residue. (For example, see ASTM method D-86.)

B-P mix

A liquified hydrocarbon product composed chiefly of butanes and propane.

Boyle's Law

A thermodynamic law which states that for an ideal gas or mixture of ideal gases at a constant temperature, the product of the absolute pressure times the volume is a constant, i.e., PV = K.


An acronym for “British thermal unit”. A measure of the quantity of energy transferred as thermal energy.

Centrifugal compressor

A device that elevates gas pressure by adding kinetic energy/velocity to the gas as it flows through an impeller.

Charles' Law

Half of the ideal gas law equation stating that at constant pressure the volume of a given mass of an ideal gas changes the volume propotionally with change in an absolute temperature.

Claus Process

A gas treatment to convert hydrogen sulfide into elemental sulfur by use of a furnace and catalyst.


A mechanical device that increases the pressure of a compressible fluid by reducing its volume.

Computational fluid dynamics ("CFD")

The process of mathematically predicting physical fluid flow by use of computer modeling.

Critical Point

The critical point for a mixture is referred to as the state of pressure and temperature at which all intensive properties of the gas and liquid phases are equal.

DEA unit

An amine plant using DEA for the reduction of hydrogen sulfide, carbon dioxide, carbonyl sulfide, and other acid gases from sour process streams.

DMR (dual mixed refrigerant) process

A process employed in the liquifaction of natural gas where two or more refrigerants are mixed and used in conjunction with multiple stages of compression to produce liquified natural gas (LNG) as efficiently as possible.

Diethanolamine (DEA)

A specific secondary amine with the chemical compound formula of HN(CH2CH2OH)2.

EOR (enhanced oil recovery)

A recovery technique that alters the chemical composition of the oil that makes it easier to extract.

EOS (Equation of state)

A mathematical expression relating pressure, temperature and volume of a fluid.

EP-mix (ethane-propane mix)

A product defined by specifications in GPA 2108.

EPA (Environmental Protection Agency)

A branch of the federal government that oversees and enforces the regulation of how humans & industry interact with nature.

Engler distillation

The process of determining the volatility characteristics of a petroleum product by distilling the product through a range of temperatures.


Floating production, storage, and offloading vessel used in offshore operations.