During the pattern approval process (in other countries this is sometimes called type approval) NMI examines the pattern (design) of an instrument to ensure that it is fit for use for trade or other legal purposes. Examination involves:

• assessment of the documentation
• assessment of the operation of the instrument against requirements (which are usually based on international recommendations published by OIML)
• performance testing to ensure that the instrument performs as intended (i.e. to within allowable maximum permissible errors) over a range of environmental and usage conditions specified in the requirements

On successful completion of the pattern approval process, you will be issued with a certificate of approval  which is valid for five years and contains an approval number. Production instruments must be:

• constructed as described in the documentation lodged with NMI and with the relevant certificate of approval and technical schedule
• marked with the approval number
• verified prior to use for trade

We issue certificates for: 

liquid measuring instruments spirit dispensers length measuring instruments area measuring instruments milk tanks load cells digital indicators weighing-in-motion systems belt weighers totalising hopper weighers automatic catchweighing instruments

multi-dimensional weighing instruments automatic tank level gauges fuel dispensers for motor vehicles fuel dispenser control systems fuel dispenser calculator/indicators liquefied petroleum gas systems compressed natural gas systems grain protein measuring instruments utility (electricity and water) meters — we approve these instruments, but we appoint authorities to test them evidential breath analysers — we approve these instruments, but we appoint authorities to test them speed measuring devices

We also issue OIML basic certificates of conformity. These certificates are accompanied by a NATA endorsement certificate and test report, and state that the instrument evaluated complies with the requirements of an OIML recommendation for patterns of instruments in use for trade. We issue OIML certificates for: