GB/T 5275.7-2014
Gas analysis.Preparation of calibration gas mixtures using dynamic volumetric methods.Part 7:Thermal mass-flow controllers (English Version)

Standard No.: GB/T 5275.7-2014
Language: Chinese, Available in English version
Release Date: 2014
Published By: General Administration of Quality Supervision, Inspection and Quarantine of the People‘s Republic of China
Latest: GB/T 5275.7-2014

Scope: This part of GB/T 5275 elaborates in detail the method of using commercially available thermal mass flow controllers to continuously prepare a calibration mixed gas containing two or more components using pure gas or mixed gas. The best level that can be achieved by using this method to prepare the calibration mixed gas is as follows: the relative measurement expanded uncertainty (obtained by multiplying the synthetic standard uncertainty by the inclusion factor k=2) U is not more than 2%. If pre-mixed gas is used instead of pure gas, a mixed gas with a mole fraction lower than 10^-6 can be prepared. The measurement of mass flow is not absolute, and mass flow controllers need to be calibrated individually. The advantage of this preparation method is that a large amount of mixed gas can be prepared continuously, and as long as an appropriate number of thermal mass flow controllers are used, multi-component mixed gas can be prepared as conveniently as binary mixed gas.

GB/T 5275.7-2014 Referenced Document

GB/T 10628-2008 Gas analysis.Comparison methods for determining and checking the composition of calibration gas mixtures
GB/T 14850-2008 Gas analysis.Vocabulary
GB/T 5275.1-2014 Gas analysis.Preparation of calibration gas mixtures using dynamic volumetric methods.Part 1:Methods of calibration

2014 GB/T 5275.7-2014 Gas analysis.Preparation of calibration gas mixtures using dynamic volumetric methods.Part 7:Thermal mass-flow controllers