Frequency response characteristics of gas sensors

In the first parl of the paper, the Bodies of the Metre Convention and in particular the CIPM and its Consultative Committees are described. At present, the main objective of the CIPM is to meet the demands for international uniformity of measurements. Technically, this is realised by key comparisons of standards for various ranges of values. They are implemented by the BIPM or the Consultative Committees and then extended world-wide by the Regional Metrology Organisalions. The results of these comparisons are given as degrees of equivalence to key reference values. An agreement is being signed by National Metrology Institutes that mutually recognises the degrees of equivalence of their standards and also their calibration and measurement certificates. Finally, an overview of new metrological activities of the CIPM is given. © 1999 Elsevier Science Lid. All rights reserved.