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MID approved gas meters

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The Measuring Instruments Directive (MID) is a European Directive (2004/22/EC) harmonising the requirements of ten different measuring instrument types, including gas meters.  A MID approved instrument will have passed specific conformity assessment procedures and have MID markings which allow the instrument to be used in any EU Member State. The aim of the Directive is to create a single market in measuring instruments for the benefit of manufacturers and, ultimately, consumers across Europe.

In the UK, the MID is implemented by Regulations for the different instrument types and these are available to download from the following website:

For gas meters the relevant legislation is:

  • The Measuring Instruments (Gas Meters) Regulations (SI 2006/2647)

Gas meters that are put into use in accordance with these Regulations are “deemed” to be stamped and MID meters therefore meet the requirements of the Gas Act 1986. However, this does not apply if the error of measurement exceeds that prescribed in the Regulations.
The Regulations came fully into force on 30 October 2006 and since this date all new designs of gas meter that are within the scope of the Directive must meet the Essential Requirements of the Directive plus the instrument specific requirements detailed in Annex MI-002.

Meters approved under UK national legislation prior to October 2006, and that are in-service prior to October 2016, can continue in-service for as long as they meet the requirements under the Gas Act 1986 but any meters newly installed after October 2016 must be MID approved.

Scope of MID

The MID is applicable to instruments for domestic, commercial and light industrial use although these terms are not defined. When the UK implemented the MID for gas meters (SI 2006/2647) it was agreed to maintain the existing regulatory scope of the Gas Act 1986 (i.e. the MID applies to gas meters designed to be used with a supply up to a maximum flow rate of 1600 m3 per hour at standard conditions of temperature and pressure).

MID Approval Process

Under the MID, gas meters are approved by notified bodies, designated by Member States. Manufacturers of gas meters can obtain approvals from any notified body in any EU Member States.

A list of notified bodies, together with the instruments they have been designated to approve, is available from:

There are a number of different conformity assessment options available for MID approval and manufacturers are free to choose between these. For gas meters the options are:

  • B+D (i.e. Type Examination and Quality Assurance of the Production Process)
  • B+F (i.e. Type Examination and Product Verification)
  • H1 (Full Quality Assurance plus Design Exanimation)

Further information is available in the SI 2006/2647 Regulations and in the Directive available from:

MID Markings

There is no statutory list of MID approved gas meters although NMO publish approval certificates issued by notified bodies in the UK.

MID approved gas meters can be identified by their specific markings, as required under the Directive. These consist of the CE marking, the MID marking which is made up of the letter ‘M’ and then the year of manufacture (for example a meter manufactured in 2011 would have the following MID marking ) and a four-digit code representing the Notified Body that approved and verified the meter. If your meter does not display these markings, it will not be MID approved.

Access copies of all MID certificates issued by UK Notified Bodies that include MID gas meters.  

In-Service Testing

There are no prescribed certification lives for MID approved gas meters so NMO, in consultation with the Industry, has developed In-Service Testing (IST) procedures for monitoring the performance of gas and electricity meters approved under the MID. These procedures will enable suppliers and asset owners to demonstrate they are fulfilling their statutory obligation to keep their meter populations in proper order for correctly registering the quantities of gas and electricity consumed.

Read more information on our IST section of the NMO website

MID Guidance

NMO have formally published guidance documents on the MID implementation Regulations (SI 2006/2647). The guidance documents seek to draw together information which relates to the regulations from other sources such as from WELMEC (European Cooperation in Legal Metrology), EU Commission, OIML (Organisation of International Legal Metrology) and ESI (European Standards Organisations).

Download the guidance notes for Gas meters (PDF, 1.1 Mb) .

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