1.1 IGEM/GM/7B supersedes the relevant scope i.e. hazardous area classification for gas metering equipment, of IGE/GM/7 Edition 2, Communication 1702, which is obsolete. The remaining scope of IGE/GM/7 Edition 2, i.e. electrical connections for gas metering equipment, has been superseded by IGEM/GM/7A, Communication 1731. 
 
1.2 This Standard has been drafted by an Institution of Gas Engineers and Managers (IGEM) Panel, appointed by IGEM’s Gas Measurement Committee, and has been approved by IGEM’s Technical Co-ordinating Committee on behalf of the Council of IGEM. 
 
1.3 This Standard has a similar scope to the relevant scope of IGE/GM/7 Edition 2, but includes additional and enhanced information.  
 
It is written such that it complements the Office of Gas Supply (OFGAS) Codes of Practice (CoPs), the Office of Gas and Electricity Markets (Ofgem) MAMCoP and the Dangerous Substances and Explosive Atmospheres Regulations (DSEAR).  
 
As such, the Standard will be of use to gas suppliers, end users, shippers, gas transporters (GTs), meter asset managers (MAMs), installation contractors, equipment manufacturers and consultants. 
 
The Standard will also be of assistance to designers and manufacturers when designing or specifying associated equipment for use in hazardous areas. 
 
1.4 This Standard is not retrospective. However, where work needs to be undertaken on a meter installation, it is recommended that such an installation be brought into line with this Standard.  
 
1.5 The de-regulation of the metering market has led to the need for new sets of rules and Standards. This has been addressed by the Ofgem MAMCoP, developed to cover whole life management of gas meter installations. The OFGAS CoPs 1/a, 1/b and 1/c which cover the installation of the meter only, will continue to apply. Businesses installing meter installations are required to be an Ofgem Approved Meter Installer (OAMI). There has also been a review and harmonisation of industry standards and CoPs to reflect the needs of the changing market.  
 
Note: Under the new arrangements, an Ofgem-approved MAM does not have to be an OAMI, but has an obligation to use an OAMI to install a meter. 
 
Notwithstanding Sub-Section 1.9, total compliance with IGEM/GM/7B is necessary for installations and modules where the meter installation has to comply with the Ofgem MAMCoP, relevant scope. 
 
1.6 This Standard makes use of the terms “should”, “shall” and “must” when prescribing particular requirements.  Notwithstanding Sub-Section 1.9: 

• the term “must” identifies a requirement by law in Great Britain (GB) at the time of publication 
• the term “shall” prescribes a requirement which, it is intended, will be complied with in full and without deviation 
• the term “should” prescribes a requirement which, it is intended, will be complied with unless, after prior consideration, deviation is considered to be acceptable. 

 
Such terms may have different meanings when used in legislation, or Health and Safety Executive (HSE) Approved Codes of Practice (ACoPs) or guidance, and reference needs to be made to such statutory legislation or official guidance for information on legal obligations. 

1.7 The primary responsibility for compliance with legal duties rests with the employer. The fact that certain employees, for example “responsible engineers”, are allowed to exercise their professional judgement does not allow employers to abrogate their primary responsibilities.  Employers must: 

• have done everything to ensure, so far as it is reasonably practicable, that “responsible engineers” have the skills, training, experience and personal qualities necessary for the proper exercise of professional judgement • have systems and procedures in place to ensure that the exercise of professional judgement by “responsible engineers” is subject to appropriate monitoring and review 
• not require “responsible engineers” to undertake tasks which would necessitate the exercise of professional judgement that is not within their competence. There should be written procedures defining the extent to which “responsible engineers” can exercise their professional judgement. When “responsible engineers” are asked to undertake tasks which deviate from this, they should refer the matter for higher review. 

 
1.8    It is now widely accepted that the majority of accidents in industry generally are in some measure attributable to human as well as technical factors in the sense that actions by people initiated or contributed to the accidents, or people might have acted in a more appropriate manner to avert them. 
It is therefore necessary to give proper consideration to the management of these human factors and the control of risk. To assist in this, it is recommended that due regard be paid to HS(G)48. 
 
1.9    Notwithstanding Sub-Section 1.5, this Standard does not attempt to make the use of any method or specification obligatory against the judgement of the responsible engineer. Where new and better techniques are developed and proved, they should be adopted without waiting for modification to this Standard. Amendments to this Standard will be issued when necessary, and their publication will be announced in the Journal of IGEM and other publications as appropriate. 
 
1.10    Requests for interpretation of this Standard in relation to matters within its scope, but not precisely covered by the current text, should be addressed in writing to Technical Services, IGEM, Charnwood Wing, Holywell Park, Ashby Road, Loughborough, Leicester, LE11 3GH and will be submitted to the relevant Committee for consideration and advice, but in the context that the final responsibility is that of the engineer concerned. If any advice is given by or on behalf of IGEM, this does not relieve the responsible engineer of any of his or her obligations. 

2.1     This Standard covers hazardous area classification for gas metering equipment. 
 
2.2 This Standard applies to meter installations of maximum operating pressure (MOP) not exceeding 75 bar. 
 
2.3 This Standard applies to meter installations containing Natural Gas (a 2nd family gas as defined by BS EN 437) in the gaseous state. 
 
Note: This Standard does not apply to either compressed or liquefied Natural Gas (CNG or LNG) installations, for example as supplied at CNG vehicle filling stations. 
 
Ambient temperatures are assumed to be in the range –25oC to 55oC. 
 
2.4 This Standard applies to primary and secondary meter installations and associated volume conversion equipment and all associated electrical equipment and connections, in industrial and commercial premises and which have been installed to BS 6400-1, BS 6400-2, IGE/GM/4, IGE/GM/6, IGE/GM/8 and IGEM/GM/5, as appropriate. These installations will also need to have been tested to and comply with IGE/UP/1A or IGE/UP/1B, as appropriate. However, it does not apply in the following circumstances when it will be necessary to use IGE/SR/25: 

• ventilation is of the forced type 
• MOP exceeds 75 bar 
• creep relief vents terminate within a meter installation’s housing 
• a competent person considers there to be unusual site circumstances 
• the installation is at a remote, unmanned, site • it is considered that leaks may go undetected • unodourised gas is metered. 

 
Note 1: DSEAR does not apply to meter installations installed in domestic premises. Therefore, it is not intended that this Standard be used for hazardous area classification in such circumstances. 
 
For the purposes of this Standard, a meter installation in domestic premises is an installation within, or near to, a domestic dwelling into which the installation supplies gas and where it is reasonable to expect that the householder will be in the vicinity of the installation on a regular basis. Such installations using a “domestic meter” will be installed in accordance with BS 6400. 
 
Note 2: For the purposes of this Standard, a meter installation in industrial or commercial premises is an installation within the boundary of the premises within which the gas load is located and where it is reasonable to expect that passers-by will be in the vicinity of the gas installation on a regular basis. This is to distinguish this type of installation from a remote site, for example a National Transmission System above-ground installation where it is reasonable to expect that persons will not be present for long periods of time and when IGE/SR/25 will need to be applied. 
 
2.5    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. 
 
2.6    This Standard 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. Such conditions will lead to a high probability of detection of any gas leak and within a short time period. Where these conditions apply, such installations can be deemed to be visited (with reference to IGE/SR/25) on a regular basis. 
 
2.7    All pressures quoted are gauge pressures unless otherwise stated. 
 
2.8    Italicised text is informative and does not represent formal requirements. 
 
2.9    Appendices are informative and do not represent formal requirements unless specifically referenced in the main sections via the prescriptive terms “should”, “shall” or “must”.