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Subject to alteration
Design,
Manufacture, Sales
Flow · Flow rate also
combined with
temperature · Pressure
PF = 1.000. As a result of this
examination an optimal measurement
point is to be determined
and the corresponding coefficient
is to be set.
For further information please
consult VDI/VDE 2640,
“Measurement of velocity area
methods in flow cross-sections”.
Höntzsch GmbH
P.O. Box 1324 D-71303 Waiblingen
Gottlieb-Daimler-Straße 37
D-71334 Waiblingen (Hegnach)
Telephone 07151/1716-0
Facsimile 07151/58402
E-Mail info@hoentzsch.com
Internet www.hoentzsch.com
U117_FA_D_e_100505 http://www.hoentzsch.com 8/8
Coefficient / Profile factor
In larger free jet as well as in larger
ducts and measuring tubes
the local velocity vp will be displayed
with PF = 1.000. PF is also
used to calculate the local velocity
vp to the average velocity vm in a
measurement cross-section:
vm = vp · PF
When measuring with cylinder
probes in circular measurement
cross-sections with interior diameter
Di
• centric positioning of the
sensor
• irrotational flow
• developed flow profile (measurement
cross-section so chosen,
that 20 Di straight, unhindered
input section amount to 10 Di
straight, unhindered output
section)
following coefficients are to be
taken as a basis:
Di PF (ZS16) PF (ZS18)
40 0.914 0.898
50 0.933 0.916
60 0.950 0.932
70 0.964 0.948
80 0.976 0.962
90 0.987 0.975
100 0.994 0.986
120 1.004 1.004
170 1.008 1.021
180 1.008 1.021
220 1.008 1.021
... 1.008 1.021
Di PF (ZS25, ZS30)
50 0.735
60 0.760
70 0.784
80 0.807
90 0.829
100 0.849
120 0.882
170 0.935
180 0.945
220 0.955
... 0.955
Vane Wheel Flow Sensors FA
If these conditions for application
of the coefficients are not prevailing
then a pre-examination of
flow should be carried out in the
greater measurement cross section
with
Electronic measurement
of physical values
Control, regulation and
recording equipment
