This report describes a COOMET key comparison of pneumatic pressure standards of six national metrology institutes (NMIs) that was carried out in the period from September 2004 to June 2006 in order to determine their degrees of equivalence in the range 50 kPa to 500 kPa of the gauge pressure. The pilot laboratory was VNIIM. The pressure standards of the participating NMIs were pressure balances of different design. The transfer standard was a 5 cm² piston–cylinder assembly accompanied by a mounting post and a weight carrier supplied by VNIIM. The pressure-dependent effective areas of the transfer standard at specified pressures were reported by the participants. The reference values were calculated as the weighted means of the results of VNIIM and PTB, which were primary and independent laboratories in this comparison. The results of this comparison were linked to the 1 MPa comparison CCM.P-K1.b using the results of the PTB obtained in both comparisons. Results by all but one participant agree with the reference values and with each other within the expanded uncertainties calculated with a coverage factor 2; roughly a half of the reported results demonstrate agreement within their standard uncertainties. With the exception of one laboratory, the results of the comparison demonstrate the equivalence of the laboratory standards and support their measurement capability statements. For laboratories whose CMCs are not presented in the KCDB yet, this comparison provides a basis for submissions for the range 50 kPa to 500 kPa of pneumatic gauge pressure.

Main text. To reach the main text of this Paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.

The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).