Determination of magnetic properties of mass standards

Project Description

Unwanted magnetic forces arising from interactions between the mass standard and the weighing instrument and/or the environment can falsify the result of a mass determination. Therefore, limits for the magnetic susceptibility and the permanent magnetic polarisation of weights are given in the international recommendation OIML R 111 (2004). Within these limits it may be assumed that the influence of the magnetic forces is negligible.

Different methods are recommended by the OIML R 111 (2004) for the determination of the magnetic susceptibility and the permanent magnetic polarisation of weights. The aim of the proposed project is to compare the results obtained by the participating laboratories for the measurement of the magnetic properties of mass standards with different shapes and nominal values using the test procedures recommended by the OIML R111 (2004).

Final Report 2015-06-05

The project has been completed and the report can be downloaded here>>

The aim of this project was to compare the results obtained by the participating laboratories when measuring the volume magnetic susceptibility and the permanent magnetic polarization of mass standards with different geometrical shapes and nominal values using the test procedures recommended by the OIML R 111 (2004). Five stainless steel mass standards with different nominal values (2 g, 1 kg and 5 kg) and outer geometries (cylindrical OIML shaped weights with recess and flat bottom, hollow cylinder) were chosen as transfer standards and sent to the participants. Altogether 21 laboratories determined the magnetic properties of the transfer standards. All participants used the susceptometer method for the determination of the magnetic properties. Additional alternative measurement procedures were used by three participating laboratories. Although discrepancies regarding the degrees of equivalence of the results were observed, all results reported by the participants would lead to consistent results for the verification of the magnetic susceptibility and permanent magnetic polarization of the travelling standards according to the OIML R 111 (2004). Participants comments on the Draft A report were considered in the Draft B and the final Draft B report was distributed to participants in December 2014.

Progress Report 2014-04-10

The EURAMET project 1110 for the determination of the magnetic properties of mass standards was continued in 2013/14. Twenty-two institutes participate in this project. All participants completed their measurements. One participant has not reported his results. Draft A report is in preparation and will be distributed to the participants as soon as possible.

Progress Report 2013-04-30

The EURAMET project 1110 for the determination of the magnetic properties of mass standards was continued in 2012/13. The pilot laboratory of the comparison measurements is PTB. Twenty-two institutes participate in this project. All participants completed their measurements. One participant has not yet reported his results. In some cases participants reported erroneous results, probably caused by calculation errors or typing errors. Therefore, participants were asked to check their calculations and resubmit corrected data until end of May 2013. The evaluation of the results is in progress. Draft A report will be prepared after completion of the evaluation with confidential codes for results of participants. A decision will be required whether the results of draft B should be made anonymous or not (participating laboratories will be asked to give a comment on draft A whether results can be identified in draft B with names or not).

Progress Report 2012-02-28

After its start in 2009, this EURAMET project for the determination of the magnetic properties of mass standards was continued in 2011/12. The pilot laboratory of the comparison measurements is PTB. Twenty-two institutes participate in this project. Since several participants were not able to perform the measurements according to the schedule and because of a new participants (Metrosert (EST), BoM (MK)), the number of petals was increased from four to five. At the beginning and the end of each petal, the magnetic properties of the traveling standards are determined by the pilot laboratory. Twenty participants performed their measurements until March 2012. Fifteen participants reported their results to the pilot laboratory.

Progress Report 2011-03-08

After its start in 2009, this EURAMET project for the determination of the magnetic properties of mass standards was continued in 2010/11. The pilot laboratory of this comparison is the PTB. Twenty-one institutes participate in this comparison. The number of petals was increased from four to five since several participants were not able to perform the measurements according to the schedule and because of a new participant (Metrosert/Estonia joined in 2011). At the beginning and the end of each petal, the magnetic properties of the travelling standards are determined by the pilot laboratory. Fourteen participants performed the measurements until March 2011. Twelve participants reported their results to the pilot laboratory. The current measurements have a delay of about one month compared with the initial schedule.

Progress Report 2010-04-22

The project was prepared by PTB and started in June 2009. Five stainless steel mass standards or different shapes and nominal values were selected as travelling standards. The standards cover a wide range of magnetic susceptibilities and permanent magnetic polarisations. A schedule was prepared with four petals and four to six participants per petal. At the beginning and the end of each petal the magnetic properties of the travelling standards are determined by the pilot laboratory. Six of twenty participants performed the measurements until March 2010. Five participants reported their results to the pilot laboratory.