24.10.2012
Nine accredited calibration laboratories will participate in the first interlaboratory comparison organized within the scope of responsibility of the Deutsche Akkreditierungsstelle GmbH (German Accreditation Body - DAkkS) to determine the magnetic properties of mass standards. PTB assumes the role as pilot laboratory regarding the preparation, coordination and evaluation of the comparison measurements.
Undesired magnetic forces can considerably affect the results of precision mass determinations. To be able to neglect these influences for practical measurements, upper limiting values for the magnetic volume susceptibility and the permanent magnetic polarisation of weights have been introduced in legal metrology by means of the International Recommendation R 111 (2004) of the Organisation Internationale de Métrologie Légale (OIML). These requirements have been adopted for DAkkS calibration laboratories and thus also have to be verified as a precondition for the calibration of mass standards. To be able to compare the results determined by the calibration laboratories, four transfer standards with different exterior geometries, nominal values and magnetic properties were selected, measured and sent to the participants. The interlaboratory comparison will be performed in five successive measuring cycles. To check the stability of the transfer standards, an intermediate measurement takes place at PTB after every second participant. After the completion of the comparison measurements at the beginning of 2013, PTB will issue a final report in which the results of all participants will be summarized and evaluated.
Contact person:
Michael Borys, Dept. 1.1, WG 1.11, e-mail: michael.borys@ptb.de