GB/T 21188-2007
Measurement of gas flow by means of critical flow Venturi nozzles (English Version)
- Standard No.
- GB/T 21188-2007
- Language
- Chinese, Available in English version
- Release Date
- 2007
- Published By
- General Administration of Quality Supervision, Inspection and Quarantine of the People‘s Republic of China
- Latest
- GB/T 21188-2007
- Scope
- This standard specifies the geometric dimensions and usage method (installation and working conditions in the system) of the critical flow venturi nozzle (CFVN) for measuring gas mass flow rate, and gives the data required for calculating the flow rate and its uncertainty. It is suitable for Venturi nozzles where the gas flow is accelerated to a critical velocity (equal to the local speed of sound) at the throat, and there is only a steady flow of single-phase gas at the throat. At the critical velocity, the gas mass flow rate through the Venturi nozzle is the maximum flow rate possible under practical upstream conditions. Critical flow Venturi nozzles should only be used within the specified limits for the nozzle throat to inlet diameter ratio and throat Reynolds number. The critical flow Venturi nozzles involved in this standard have done a large number of direct calibration tests, which can ensure that the given critical flow Venturi nozzle discharge coefficient is within a predictable uncertainty limit. The data given in this standard are suitable. In the following cases: the upstream pipeline of the critical flow Venturi nozzle is a circular cross-section pipeline; or the upstream of the critical flow Venturi nozzle, or the upstream of a set of critical flow Venturi nozzles installed in groups can be regarded as a large space. This group configuration provides the possibility to install critical flow venturi nozzles in parallel, so that a larger flow rate can be obtained. For high accuracy measurement, this standard discusses the precise machining of critical flow venturi nozzles for low Reynolds numbers.
GB/T 21188-2007 history
- 2007 GB/T 21188-2007 Measurement of gas flow by means of critical flow Venturi nozzles
