IGEM/GM/7B Hazardous area classification for gas metering equipment.
This Standard covers the classification of dangerous areas,
those in which explosive gas mixtures may be present, for gas
This standard covers hazardous area classification for gas
metering equipment and applies to meter installations containing
Natural gas in the gaseous state at maximum operating pressure not
exceeding 75 bar. It covers primary and secondary meter
installations, associated volume conversion equipment and all
associated electrical equipment and connections, in industrial and
commercial premises which have been installed to other BS and IGEM
standards as appropriate. However, it does not apply in the
following circumstances, where IGE/SR/25 should be used
- Ventilation is of the forced type
- MOP exceeds 75 bar
- Creep relief vents terminate within a meter installation's
- A competent person considers there to be unusual site
- The installation is at a remote, unmanned site.
- It is considered that leaks may go undetected.
- Unodourised gas is metered.
This standard may be applied for meter installations in existing
premises where ventilation is present but where it is difficult or
impossible to confirm that levels of ventilation comply with
current design standards. It uses a methodology that assumes meter
installations are protected from external interference and located
in populated areas, or sites are manned in industrial and
commercial premises, leading to a high likelihood that any gas leak
will be detected within a short period. It contains information
about legal considerations and then extensive details of the
concept, requirements and classification of hazardous areas