The inter-comparison concerns a 20 L steel pipette, which was one of three volume standards in the Key-comparison CCM.FF-K4. This first round involving eight laboratories of which three came from Euromet (PTB, INRIM (former IMGC), SP) is now finished and reported on the BIPM website. To link the European laboratories and their volume calibration capability to the global reference value it is suggested to circulate this standard slightly changed among interested participants making them perform the same calibration. The interested volume is the amount of water that can be delivered out of the standard at well defined conditions. The technical protocol for this exercise will be the same in all technically relevant aspects. This standard can be departed and the inner surface cleaned as to prepare excellent conditions for a high repeatability. The outcome from the first round has proven a very high stability and an a very good of degree of equivalence if following the technical advise carefully. The overall agreement is expected to lie within 50 ppm.
The project will be piloted by IPQ - Elsa Batista and SP - Peter Lau. SP and IPQ have been involved in previous cooperation regarding EUROMET Projects "Calibration Inter-comparison of a 5-litre volume glass standard" and "Volume calibration of a 100 ml Gay-Lussac Pycnometer". The standard was produced by CENAM (Mexico) and the volume is changed mechanically for the European inter-comparison. The cost for this work and the shipping to and from Europe we have to share amongst the laboratories.
Final Report 2009-07-31
The comparison has been completed and results are available in the KCDB.
The comparison amongst 14 European and the pilot for the key comparison was conducted within one year. All laboratories could be linked to the key-comparison-reference value confirming all participants CMC-claims. The agreement with the KCRV was for two laboratories within 70 for the rest within 30 ppm, which was better than the optimistically expected 50 ppm. The reason was the exceptional transfer standard in stainless steel with a highly polished inner surface allowing extremely good reproducibility for this type of calibration objects. This outcome indicates that the methods and equipments used are comparable. It is the interaction with the usual calibration objects that limits the calibration uncertainties in routine work.