Final report on supplementary comparison COOMET.PR-S7: Laser power responsivity (COOMET 599/RU/13)

The National Institute of Standards and Technology (NIST), USA and the All-Russian Research Institute for Optical and Physical Measurements (VNIIOFI), Russia agreed in February 2013 to conduct a comparison on the laser power responsivity at wavelengths of 532 nm, 1.064 μm and 10.6 μm. The aim of this comparison is to assess the equivalence of the laser power responsivity between two laboratories. The comparison was conducted within the COOMET regional metrological organization (COOMET 599/RU/13) and was registered in the BIPM Key…

Calibration of diameter standards (EURAMET.L-K4.2015)

At its meeting in October 2014, the EURAMET TC for Length, decided upon a key comparison on the calibration of diameter gauges, named EURAMET.L-K4.2015. Twenty National Metrology Institutes and one Designated Institute from Europe, Asia and South America participated in this comparison, which was carried out in two parallel groups. Twelve laboratories from EURAMET participated in group 1, while ten laboratories from EURAMET and two laboratories from GULFMET and SIM participated in group 2. To provide the link three laboratories, CEM,…

Supplementary comparison APMP.RI(I)-S1 of standards for absorbed dose to water in 60 Co gamma radiation at radiation processing dose levels

Four national standards for absorbed dose to water in 60 Co gamma radiation at the dose levels used in radiation processing have been compared over the range 0.1 kGy to 50 kGy using alanine dosimeters of the Office of Atoms for Peace (OAP) as transfer dosimeters. The comparison was piloted by the OAP who also participated. Two laboratories from the original six were forced to withdraw due to equipment problems. The results at low doses (0.1 kGy) showed a much wider…

International comparison CCQM-K117 ammonia

At the highest metrological level, ammonia gas standards are commonly prepared gravimetrically as Primary Standard Mixtures or using a dynamic standard. This international key comparison addressed the measurement of the amount fraction ammonia in nitrogen, to support calibration and measurement services for mainly environmental applications. The nominal amount fraction was 14 μmol mol -1 . The results in this Track C key comparison on the composition of biogas are generally good. To reach the main text of this paper, click on Final…

Automatic alignment technique for the suspended coil in the joule balance

An automatic alignment technique was developed for the joule balance to reduce the uncertainty caused by alignment errors. Using the flexures and decoupling structure of the suspended coil, the proposed alignment system can automatically recognize the linear relationship between the initial position and posture of the suspended coil when the current is off, and its parasitic horizontal linear and angular displacements when the current is on. Subsequently, several actuators including mini-motors and an X – Y stage are controlled to adjust…

International comparison CCQM-K74.2018: Nitrogen dioxide, 10 μmol mol-1

The CCQM-K74.2018 comparison evaluated the level of compatibility of nitrogen dioxide (NO 2 ) in nitrogen standards at nominal amount fractions of 10 μmol/mol provided by National Metrology Institutes. Fourteen laboratories participated in the comparison, submitting two standards each, with comparative measurements and comparison coordination undertaken by the BIPM. Measurements at the BIPM were performed from July 2018 to May 2019. The key comparison reference values (KCRV) for each submitted standard were established at three different times during the measurement period…

Primary standard for traceability in low liquid hydrocarbon fuel flow rates

We developed a primary standard for low liquid hydrocarbon flow rates that works on light oil (diesel), kerosene and industrial gasoline. To achieve a calibration accuracy of below 0.1% over a wide flow range from 0.02 L h −1 to 100 L h −1 as required by the industry, this primary standard adopts the gravimetric calibration method performing static weighing with flying-start-and-finish, incorporating a compactly designed conical rotating double-wing diverter for the upper flow range (1 L h −1 to 100…

Investigation of the uncertainty contributions of the alignment of PTB’s double-ended interferometer by virtual experiments

High-accuracy length measurements of prismatic bodies (e.g. gauge blocks) are usually performed by means of single-ended interferometers. To perform these measurements, the gauge block must be wrung to a reference plate. The quality of contact affects the measured length and also the wringing process wears down or damages the measuring faces. Furthermore, it limits the use of such interferometers to bodies that are suitable for wringing. PTB’s double-ended interferometer allows high-accuracy length measurements that are traceable to the International System of…

Development of a new KRISS low frost-point generator with improved uncertainty from 7 nmol·mol −1 to 1000 nmol·mol −1

A new saturator-based low frost-point generator (LFPG 2) is developed at the Korea Research Institute of Standards and Science (KRISS), and its uncertainty is evaluated from 7 nmol·mol −1 to 1000 nmol·mol −1 in nitrogen. The humidity generator operates in the two-temperature two-pressure mode to achieve target water vapor concentrations. First, the apparatus of the generator and the operation procedures, including purging mode and generation mode, are introduced in depth. Then, all uncertainty factors that affect trace-moisture generations are analyzed using a…

On-site comparison of Quantum Hall Effect resistance standards of the NMC A*STAR and the BIPM: Ongoing key comparison BIPM.EM-K12

The ongoing on-site comparison BIPM.EM-K12 is part of the BIPM programme implemented to verify the international coherence of the primary resistance standards. It allows National Metrology Institutes (NMIs) to validate their implementations of the Quantum Hall Effect (QHE) for dc resistance traceability by comparison to the reference maintained at the BIPM. The realization of the ohm from the QHE-based standard of the NMIs at 100 Ω is compared with that realized by the BIPM from its own transportable quantum Hall resistance…