In May 2024, the Executive Committee of the Asia Pacific Metrology Programme (APMP) approved the Technical Committee Initiative (TCI) proposed by Technical committee of fluid flow (TCFF) and the Developing Economies' Committee (DEC) for the project "Research on Low Pressure Gas Flow Standard System and Inter-Comparison at Low Flow Rate Range," with the project code TCFF_01_TCI2024. The purpose of this project is to assist all TCFF members in conducting research on the calibration control and procedures of low-pressure gas (under 7 bar pressure) within the flow rate range of 100 mL/min to 10 mL/min, and to verify the consistency of calibration values between laboratories. As the accuracy of gas calibration at low-pressure, low flow rates (under 7 bar, from 100 mL/min to 10 mL/min) is crucial in specialized areas such as the preparation of chemical specialty gases for semiconductor processes, standard reference gases, and the accuracy check of leak detection sensors. Due to variations in the primary standard systems and calibration environment control methods employed by different laboratories, the influencing factors on measurement uncertainty differ, and findings during the CCM.FF-K6.2017 Key Comparison, it was observed that measurements at flow rates below 100 mL/min are challenging to control, leading to significant differences in measurement results.

  Therefore, an workshop and an comparison study were organized in our project for the purpose of not only study the influences in different primary standards but also determining the degrees of equivalence of the participating laboratories spanning the gas flow range from 100 mL/min of nitrogen to 10 mL/min of nitrogen (standard volumetric flow reference conditions are 101.325 kPa and 0 °C).

  A three-day kick-off hybrid workshop was held in Hsinchu, Taiwan (CMS/ITRI, Chinese Taipei) from May 29 to May 31, 2024. Prior to this, despite the project overseer actively initiating various communications, participants from several NMIs and economies were unable to attend the kick-off workshop due to international travel issues and visa issues or other planning factors. Consequently, the pilot laboratory, CMS/ITRI, adapted the workshop to a hybrid format, where lectures were delivered online, but hands-on exercises were still conducted in physical. However, NIM and UzNIM were still unable to participate workshop, and NMLPHIL attended the lecture portion of the workshop on May 29 online. NMIA and NIMT participated in all online lectures on May 29 and 30, but did not join the practical sessions. Mr. Simon Dignan from NMIA delivered a lecture on the PVTt system remotely. A total of six APMP members (including from CMS/ITRI, KRISS, NMC/A*STAR, NMIJ/AIST, NPLI, and VMI) participated in all activities of the workshop.

  The subsequent TCI comparison work has officially begun, with the calibration of the comparison standard parts starting at the pilot laboratory (CMS/ITRI) in August 2024. The comparison item is expected to be transferred from the pilot laboratory to KRISS on September 23.

         Table 1, Schedule and Content of TCFF TCI&DEC Kick-off Hybrid Workshop

 Figure 1, Picture of the Lectures in TCFF TCI&DEC workshop

Figure 2, Picture of the Hand-on Experiment in TCFF TCI&DEC workshop

Contributor: Dr. Chun-Lin Chiang, CMS/ITRI, Chinese Taipei