Research on Intermediate Check Method for Gas Flow Standard Devices Using Critical Flow Venturi Nozzles

Intermediate check plays a critical role in the value traceability system of a measuring laboratory. The Judgement Method of E_n value is a common method used for intermediate checks of gas flow standard devices. However, this method heavily relies on the long-term stability of the check standard, which can lead to erroneous judgments. To address this issue, we designed a new method that combines two comparative tests. The first test compares the critical flow venturi nozzles within the device, and the second test compares several devices within the laboratory based on the same measurement principle. This article provides a description of the procedures involved in the intermediate check method, and we analyze the test data using an example. Our method can fully monitor the reliability of the device's main standards, as well as check the reliability of several intralaboratory devices at any time. Furthermore, our approach reduces the measurement error caused by changes in installation and operating environments. In summary, this intermediate check method is more convenient and efficient, making the verification process for critical flow venturi nozzles in gas flow standard devices more reliable.