User Manual

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Siemens Control device PN40, safety function to DIN EN 14597 CE1N4388en
Smart Infrastructure 2020-01-09
Spring water cooling as an example of avoiding cavitation:
Chilled water = 12 °C
p
1
= 500 kPa (5 bar)
p
4
= 100 kPa (1 bar)
(atmospheric pressure)
p
max
= 300 kPa (3 bar)
p
3-3’
= 20 kPa (0.2 bar)
p
D
(throttle) = 80 kPa (0.8 bar)
p
3
’ = pressure after
consumer in kPa
p
3
p
1
4382Z07

p
max
M
p
3
'
p
D
p
4
Working
pressur
e [bar]
Medium temperature [°C]
Working pressure and medium temperature staged as per DIN 4747-1
Current local legislation must be observed.
Absolute working pressure [bar]
Medium temperature [°C]
1
wet steam
avoid
2
saturated steam
permissible range of use
3
1
superheated steam
For saturated steam and superheated steam the differential pressure p
max
across
the valve should be close to the critical pressure ratio.
Pressure ratio =
%100
p
pp
1
31

−
p
1
= absolute pressure before valve in kPa
p
3
= absolute pressure after valve in kPa
Working pressure
and medium
temperature
Fluids
Working pressure
and medium temper-
ature
Saturated steam
Superheated steam
Recommendation