Best practice for the dissemination of the kilogram
Project Description
In a tri-lateral between VSL, IPQ and PTB in 2010, discrepancies were found in the density of a viscous oil measured by vibrating tube density meters. A follow-up was agreed which could also serve as preparation for the EURAMET density comparison (using the same devices) planned in 2012. The density of three increasingly viscous oils was measured at 10, 20, 40 and 70 °C. The aims of this project are:
- to establish the level of equivalence with regard to the density correction of viscous oils
- to gain insight in the various methods used
- to link density measurements performed by non-EURAMET accredited laboratories tointernational measurements in order to support their CMCs
Final Report 2016-05-03
The project has been completed and the report can be downloaded here>>
Progress Report 2015-04-30
Working on Final Report
Progress Report 2013-04-02
A meeting was held on March 21, 2013 in Croatia during the annual EURAMET meeting. Discussed were some of the results found in the 16 inventory documents which have been gathered from various NMIs and it was decided which steps are to be taken next. The documents, the initial summary and a list of relevant papers will be sent to all participants for studying. Some matters in the inventory documents will require further clarification.
Based on practical experience it seems at this stage unlikely that further optimisation of the weighing designs will be beneficial, because the deviations caused by environmental conditions or limitations of the balances are larger than the expected reduction in uncertainty due to improvement of the designs.Having access to the practical approach and methods used by other NMIs however, has proven to be very valuable and should be open to all. The exact form of this access is yet to be decided.
Progress Report 2012-03-07
The kick-off meeting was held on February 29, 2012 at BEV, Vienna.
Discussed were the goals of the project, the present situation regarding the dissemination of the kilogram at the participant's institutes and the set-up of the inventory document to achieve the first goal.
On March 2, 2012, the current status of the project was presented to the EURAMET SC Mass. After finishing the set-up, the inventory document will be sent to all EURAMET members to be filled in. Based on this overview, the next steps will be decided.
Subdivision schemes for the dissemination of the kilogram have been established many years ago when nearly all measurements were performed manually. This meant that the number of measurements and combinations had to be restricted. Nowadays automated mass handlers and robots make it possible to increase the number of measurements and allow new combinations to be included. The aims of this project are:
- to establish which schemes, calculation methods (including uncertainty evaluation methods, statistical tools for evaluation of the measurement process) and equipment are presently used
- to determine if it is possible to optimize the subdivision schemes for different types of robots and mass handlers, and for different typical compositions of weight sets, taking into account efficiency, measurement uncertainty and robustness,
- to provide guidelines for the best practice to disseminate the kilogram