Flow-X─ Function Reference
4-229
Flow-X General functions - fxISO5167_Venturi
fxISO5167_Venturi
The function calculates the mass flow rate for classical Venturi tube pressure differential flow devices
according to the ISO-5167 standard.
Compliance
ISO-5167 - 1991 Measurement of fluid flow by means of pressure differential devices, 1st edition, 1991
ISO-5167 Amd.1 : 1998(E)
ISO-5167 - 2003 Measurement of fluid flow by means of pressure differential devices inserted in
circular cross-section conduits running full, 2nd edition, 2003
Function inputs and outputs
Function inputs
Remark
EU
Range
Default
Name
Optional tag name, tag description and tag
group
Differential Pressure
Differential pressure over the primary flow
device measured at the up- and
downstream pressure tappings, which
need to be in the positions as specified in
the standard
mbar
0
Pressure
Upstream pressure value of the fluid at
metering conditions
bar(a)
0
Temperature
Down- or upstream temperature of the
fluid at metering conditions
°C
0
Density
Down or upstream density of the fluid at
metering conditions
kg/m3
0
Dynamic Viscosity
Dynamic viscosity of the fluid
Pa.s
0
Isentropic Exponent
Also referred to as
(kappa). For an ideal
gas this coefficient is equal to the ratio of
the specific heat capacity at constant
pressure to the specific heat at constant
volume. According to the ISO standard this
ratio may be used, when the real value is
unknown.
-
0
Pipe Diameter
Internal diameter of the pipe at reference
temperature
mm
0
Pipe Expansion
factor
The thermal expansion coefficient of the
pipe material
1/°C
0.0000108
Pipe Reference
temperature
The reference temperature that
corresponds to the 'Pipe diameter' input
value
°C
20
Venturi Diameter
Venturi diameter at reference
temperature
mm
0
Venturi Expansion
factor
The thermal expansion coefficient of the
Venturi material
1/°C
0.0000163
Venturi Reference
Temperature
The reference temperature that
corresponds to the 'Venturi diameter'
input value
°C
20
Configuration
The type of classical venturi tube.
Three configurations are permitted by the
ISO5167 standard. Each configuration has
a different calculation of the discharge
coefficient and of the expansion factor
1: As cast convergent section
2: Rough welded
3: Machined
4: User-defined (not according to the
-
2
Содержание flow-x
Страница 1: ...Function Reference Certified flow calculations Flow and batch calculations Worksheet functions...
Страница 331: ...Flow X Function Reference 5 331 Flow X IO Functions fxPT100Table...
Страница 349: ...Flow X Function Reference 6 349 This page is intentionally left blank for user notes...
Страница 350: ...6 350 Flow X Function Reference This page is intentionally left blank for user notes...