National Physical Laboratory

Proficiency testing schemes

Proficiency testing schemes

Natural gas and refinery gas proficiency testing schemes

NPL organises natural gas and refinery gas proficiency testing (PT) schemes to enable calibration and testing laboratories to achieve greater confidence in their analyses of the composition of these gases.

These PT schemes involve the distribution of accurate natural gas standards of known composition to participating laboratories for 'blind' testing. Participants analyse the mixtures and send their results back to NPL. At the conclusion of the scheme, a report is provided to each laboratory, which includes an anonymous comparison of all participants' results.

'On-demand' proficiency testing schemes

Bilateral, 'on-demand' PT schemes can also be organised. These are available for any gas mixture, and their scope and timing are arranged at the convenience of the participating laboratory.

The procedure for an 'on-demand' PT scheme is as follows:

  1. NPL prepare and validate a Primary Reference Gas Mixture (PRGM).
  2. The PRGM is sent (without the certificate) to the participating laboratory.
  3. The external laboratory measures the composition of the PRGM and reports their results to NPL.
  4. NPL provides the external laboratory with a comparison of their results against the gravimetric composition of the mixture, and a certificate showing the composition of the PRGM.
  5. The external laboratory retains the PRGM for future use.

Bilateral, 'on-demand' PT schemes can be carried out with either UK or international laboratories. Details of the operation of these schemes can be found in the procedure document Adobe Acrobat PDF file


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Last Updated: 16 Jun 2016
Created: 25 Sep 2013


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