ISO 9300:2005
Measurement of gas flow by means of critical flow Venturi nozzles

Standard No.

ISO 9300:2005

Release Date

2005

Published By

International Organization for Standardization (ISO)

Status

Be replaced

Replace By

ISO 9300:2022

Latest

ISO 9300:2022

Scope

This standard specifies the geometric dimensions' and usage (installation and working conditions of the system) of critical flow venturi nozzles (CFVN) for measuring gas mass flow, and gives the information required to calculate the flow rate and its uncertainty. material. This standard applies to Venturi nozzles in which the gas flow accelerates to a critical speed (equal to the local speed of sound) in the throat and only a single-phase steady gas flow exists in the throat. At critical velocity, the mass flow rate of gas flowing through the Venturi nozzle is the maximum flow rate possible under practical upstream conditions. Critical flow Venturi nozzles may only be used within the specified limits of the nozzle throat-to-port diameter ratio and the throat Reynolds number. The critical flow venturi nozzles involved in this standard have undergone a large number of direct calibration tests, which can ensure that the given outflow coefficient of the critical flow venturi nozzle is within a certain predictable uncertainty limit. The information given in this standard is suitable for the following situations: the pipeline upstream of the critical flow Venturi nozzle is a pipeline with a circular cross-section; or the upstream of the critical flow Venturi nozzle, or a set of critical flow Venturi nozzles installed in a group The upstream can be seen as a large space. This group configuration provides the possibility of parallel installation of critical flow venturi nozzles, thus achieving greater flow rates. For high accuracy measurements, this standard discusses accurately machined critical flow venturi nozzles for use at low Reynolds numbers.

ISO 9300:2005 history

• 2022 ISO 9300:2022 Measurement of gas flow by means of critical flow nozzles
• 2005 ISO 9300:2005 Measurement of gas flow by means of critical flow Venturi nozzles
• 1990 ISO 9300:1990 Measurement of gas flow by means of critical flow Venturi nozzles