To support the industry and stakeholders in the use of consistent terminology, Ipieca, IOGP, GIE and MARCOGAZ prepared this methane emissions glossary covering the whole natural gas value chain.

Intended for policymakers and regulators working on methane regulation in Europe, this glossary will be updated to reflect new legislation and technologies.

All | # A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
There are currently 9 names in this directory beginning with the letter P.

Penetration of a permeate (such as a liquid, gas, or vapour) through a solid. (Note - In case of natural gas through pipelines made of polymer materials, it is directly related to the pressure of the gas, intrinsic permeability of polymer materials and wall thickness. Polymers can be polyethylene, polyamide or PVC.)

Pneumatic device emissions
Emissions caused by gas operated devices (control valve actuators, chemical injection pumps, etc). These can be continuous or intermittent emissions. [11]

Pneumatic emission sources
Devices where natural gas pressure is used as an energy source to operate various instrumentation and equipment, ultimately resulting in emissions of the actuation gas. This type of instrumentation and equipment is normally used in places where electrical power or instrument air are not available. [8]

Point of delivery
Point where the gas is transferred to the user. This can be at a means of isolation (e.g. at the outlet of an LPG storage vessel) or at a meter connection. For this document the point of delivery is typically nominated by the distribution system operator and can be defined in National Regulations or Codes of Practices. [11]

Pressure regulating station
Asset comprising all the equipment including the inlet and outlet pipework as far as the isolating valves and any structure within which the equipment is housed, used for gas pressure regulation and over-pressure protection. [2]

Pressure regulator
Device which reduces the gas pressure to a set value and maintains it within prescribed limits. [12]

Pressure relief valve
A safety device designed to release gas in the event of an unacceptable pressure being detected within the system it protects. [2]
(Note - Safety relief device is the same)

Pump down
A process where a compressor is used to remove pressurized gas from an isolated pipeline or vessel, by pumping it into another pressurized gas system.

Process for safely removing air or inert gas from pipework and/or pipeline components and replacing it with gas, or the reverse process. [12]


[1] Directive 2009/73/EC of the European Parliament and of the Council of 13 July 2009

[2] EN-12186 – Gas infrastructure – Gas pressure regulating stations for transmission and distribution – Functional requirements

[3] EN-12327 – Gas infrastructure – Pressure testing, commissioning and decommissioning procedures – Functional requirements

[4] EN-12583 – Gas Infrastructure – Compressor stations – Functional requirements

[5] EN-15446 – Fugitive and diffuse emissions of common concern to industry sectors – Measurement of fugitive emission of vapours generating equipment and piping leaks

[6] GIE & MARCOGAZ Report “Potential ways the gas industry can contribute to the reduction of methane emissions”

[7] IPIECA/API/IOGP (2020). Oil and gas industry guidance on voluntary sustainability reporting

[8] IPIECA Methane Glossary

[9] ISO 14532 – Natural gas — Vocabulary

[10] JCGM-100 – Evaluation of measurement data – Guide to the expression of uncertainty in measurement. s.l.: Committee for Guides in Metrology (JCGM/WG 1), 2008

[11] MARCOGAZ – Assessment of methane emissions for gas Transmission and Distribution system operators, 2019 Assessment+of+methane+emissions+for+gas+Transmission+and+Distribution+system+ operator.pdf?t=1602849054

[12] MARCOGAZ – Guidance for using the MARCOGAZ methane emissions reporting template – DSO, TSO, LNG receiving terminals and UGS

[13] MGP Reducing methane emissions: Equipment leaks

[14] MGP Reducing methane emissions: Identification, detection, measurement and quantification

[15] MGP Reducing methane emissions: Transmission, storage, LNG terminals and distribution

[16] Oil and Gas Methane Partnership Technical Guidance Documents

[17] Regulation (EC) No 715/2009 of the European Parliament and of the Council of 13 July 2009

[18] US EPA – ‘Method 21: Determination of volatile organic compound leaks’