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Pattern approval requirements

During the pattern approval process, we examine the design of an instrument. To comply, the instrument pattern must meet its related mandatory requirements.

Requirements are either:

  • prefixed with ‘NMI R’ and based on an International Organization of Legal Metrology (OIML) recommendation of the same name and number
  • prefixed with ‘NMI M’ and have been prepared by the National Measurement Institute (NMI).

For accessible versions of these documents, email our pattern approval section.

NMI R 129 Multi-dimensional measuring instruments

Volume and flow requirement documents


NMI R 81 Dynamic measuring devices and systems for cryogenic liquids

NMI R 105 Direct mass flow measuring systems for quantities of liquids

NMI R 139 Compressed gaseous fuel measuring systems for vehicles

NMI R 125 Measuring systems for the mass of liquids in tanks

Mass and weighing requirement documents

NMI R 33 Conventional value of the result of weighing in air

NMI R 51 Automatic catchweighing instruments

NMI R 106 Automatic rail weighbridges

NMI R 107 Discontinuous totalising automatic weighing instruments (totalising hopper weighers)

Point of sale (POS) systems requirement documents

NMI M 7 Pattern approval specifications for point of sale systems