NEN EN ISO 9300 : 2005

Foreword
1 Scope
2 Terms and definitions
  2.1 Pressure measurement
  2.2 Temperature measurement
  2.3 Venturi nozzles
  2.4 Flow
3 Symbols
4 Basic equations
  4.1 State equation
  4.2 Flow-rate under ideal conditions
  4.3 Flow-rate under real conditions
  4.4 Critical mass flux
5 Applications for which the method is suitable
6 Standard critical flow Venturi nozzles (CFVN)
  6.1 General require
  6.2 Design
7 Installation requirements
  7.1 General
  7.2 Upstream pipeline
  7.3 Large upstream space
  7.4 Downstream requirements
  7.5 Pressure measurement
  7.6 Drain holes
  7.7 Temperature measurement
  7.8 Density measurement
  7.9 Calculated density
8 Calculation methods
  8.1 Mass flow-rate
  8.2 Discharge coefficient, C[d']
  8.3 Critical flow function, C[*], and real gas critical
      flow coefficient, C[R]
  8.4 Conversion of measured pressure and temperature to
      stagnation conditions
  8.5 Maximum permissible downstream pressure
9 Uncertainties in the measurement of flow-rate
  9.1 General
  9.2 Practical computation of uncertainty
Annex A (normative) Venturi nozzle discharge coefficients
Annex B (normative) Tables of values for critical flow
                    function C[*] - Various gases
Annex C (normative) Computation of critical mass flux for
                    natural gas mixtures
Annex D (normative) Mass flow correction factor for
                    atmospheric air
Annex E (normative) Computation of critical mass flux for
                    critical flow nozzles with high nozzle
                    throat to upstream pipe diameter ratio,
                    beta > 0,25
Bibliography

Specifies the geometry and method of use (installation in a system and operating conditions) of critical flow Venturi nozzles (CFVN) used to determine the mass flow-rate of a gas flowing through a system. It also gives the information necessary for calculating the flow-rate and its associated uncertainty.