1. Repeatability of verification or calibration results

In the new specification, "repeatability of verification or calibration results" is used instead of "repeatability of measurement standards". This modification is more in line with the requirements of repeatability tests in measurement standard inspections, and its purpose is to give the impact of all random effects on the verification or calibration results during the verification or calibration process, because it is the direct source of uncertainty in the verification or calibration results.

Take the secondary platinum resistance thermometer standard device as an example. If a repeatability test is conducted according to the "repeatability of verification or calibration results" in the new specification, it is necessary to use the standard device to perform n independent repeated measurements on the conventional measured object under repeatable measurement conditions, and use the Bessel formula to calculate the repeatability of the verification or calibration results for 4 seconds. The results include not only the influence of the measurement standard device, but also the influence of the measured object itself, the environment, personnel and other factors, so it can be directly used as the uncertainty source for the uncertainty assessment of the verification or calibration results.

Requirements for major changes in environmental conditions and facilities

In the new regulations, Fan Zeng added the measurement standard requirements for major changes in environmental conditions and facilities (see new specification 7.2 for details). Combined with actual work, several issues in this clause are explained as follows.

First, fill in the self-check form for major changes in environmental conditions and facilities. The "Basic Information of Changes" should briefly describe the reasons, extent and consequences of changes in the environmental conditions and facilities of the measurement standard. Self-check the main items in the "Measurement Standard Stability Assessment". If the change has no effect on the main measurement characteristics of the measurement standard, such as standard materials, gauge blocks and other measurement standards whose stability is not affected by the environment, you can briefly explain the situation; if the change has an impact on the main measurement characteristics of the measurement standard, the stability assessment of the measurement standard should be re-conducted. According to the requirements for the stability assessment of the new metrological standard, it is recommended that the stability assessment time be no less than half a year.

The repeatability test of the verification or calibration results should be conducted at least once to confirm whether its repeatability meets the requirements. Through stability and repeatability tests, confirm whether the measurement standard can maintain normal working conditions. If necessary, re-track the measurement standard and supporting equipment. Fill in the corresponding columns with changes in measurement characteristics such as the stability of the measurement standard, the repeatability of the verification and calibration results before and after the change, and the traceability of the measurement standard and main supporting equipment.

The second is about the archiving of this form. After the standard setting unit conducts self-inspection in accordance with the requirements, it shall report to the metrology administrative department of the people's government responsible for the inspection, submit a self-inspection form, and include the self-inspection form in the management scope of the metrology standard document set.

3. Fixed-point and regular traceability of metrology testing and measurement standards

Article 4.1.3 of the new specification has clear requirements for the traceability of metrology standard instruments and their supporting equipment, requiring that "metrology standard instruments shall be regularly verified or calibrated through social public metrology standards established by statutory metrology verification institutions or metrology technical institutions authorized by the metrology administrative departments of the people's governments at or above the county level to ensure their traceability". In combination with actual work, here is a specific explanation of the understanding of "fixed point, regular".

"Fixed point" means that in principle, metrology standards should be traced back to fixed statutory metrology institutions or metrology technical institutions authorized by the metrology administrative departments of the people's governments at or above the county level, and shall not be changed at will without special circumstances. The meaning of "cycle" means that if the calibration is traced back, the calibration cycle shall not exceed the cycle specified in the metrology calibration procedures. If the source is traced through calibration,

New specification 7.2 stipulates: "If the metrological verification procedures or metrological technical specifications based on verification or calibration are changed, they should be recorded in the resume of the metrological standard; if the change leads to substantial changes in the metrological standard or main supporting equipment, main metrological characteristics or verification methods and calibration methods, an application for review should be made in advance, and a comparison table of changes in metrological verification procedures or technical specifications should be provided during the review."