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 requirements
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