Holland, P E; Woods, P T; Brookes, C; Uprichard, I J; Quincey, P; Robinson, R A; D'Souza, H; Milton, M J T; Goody, B; Bell, W; Alphonso, D (2001) The development of gas standards and calibration techniques for measurements of vehicle, aircraft and industrial emissions, natural gas, occupational exposure and air quality. Accred. Qual. Assur., 6 (3). pp. 120-129.

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Abstract

The National Physical Laboratory (NPL) is involved in the dissemination of nationally traceable standards to which measurements of air quality, occupational exposure and air pollution source emissions, and natural gas analyses, can be referenced. This has required the development of national primary gas standards using absolute gravimetric and other techniques, and the development of dynamic calibration techniques for gaseous species which would be unstable in high-pressure cylinders. The methodology used for preparing gas standards gravimetrically is described, together with the rigorous quality assurance measurements and consistency checks which are used to demonstrate their accuracy and stability. The uncertainty budget assigned to these standards will also be summarised. NPL primary standards are used to certify traceable secondary gas standards which are disseminated so as to ensure the accuracy of gas analysis measurements. Examples of the application of these secondary standards are presented. The gas standards are employed in proficiency testing of industrial stack-testing organisations, and results in the initial rounds are presented. NPL gas standards are also now being used as a basis of the United Kingdom Environment Agency's new type-approved and certification scheme for continuous industrial stack-emission analysers. A recent important international initiative, in the field of gas analyses, is the agreement by national standards laboratories across the world to demonstrate the equivalence of their calibrations, by means of key comparisons between them. These worldwide key comparisons are complemented in Europe through the EUROMET initiative which seeks to establish the equivalence and comparability of calibration standards held at national standard laboratories across Europe. Examples of these intercomparisons are presented.

Item Type:	Article
Keywords:	traceability, gas standards, calibration, quality assurance, proficiency testing, international comparisons
Subjects:	Environmental Measurement Environmental Measurement > Atmospheric Science, Emission and Security
Last Modified:	02 Feb 2018 13:17
URI:	http://eprintspublications.npl.co.uk/id/eprint/2056

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