User Manual

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Siemens 2-port seat valves PN25 with flanged connection CM1N4373en
Building Technologies 15.11.2010
Working pressure [bar]
-20
25
24
23
22
21
20
19
18
-8
0
1
0
-70
-1
0
180
-6
0
-4
0
0
2
0
8
0
10
0
20
0
4373D05
150120
VVF52.. VVF52..A VVF52..G
VVF52..M
Medium temperature [°C]
Working pressure and medium temperature staged as per ISO 7005
Current local legislation must be observed.
Absolute working pressure [bar]
100 110 120 130 140 150 160 170 180
1
10
2
6
4
3
2
1
3
4373D09
SKB.. SKD..
≤ 180 °C VVF52..G
Medium temperature [°C]
wet steam avoid
saturated steam
superheated steam
permissible range of use
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
Subcritical range Supercritical range
%42%100
p
pp
1
31


%42%100
P
pp
1
31


Pressure ratio < 42% subcritical Pressure ratio  42% supercritical
(not recommended)
k
)pp(p
m
4.4k
313
vs




k
p
m
8.8k
1
vs


m

= steam quantity in kg/h
k = factor for superheating of steam = 1 + 0.0012 · T (k = 1 for saturated steam)
T = temperature differential in K between saturated steam and superheated steam
Working pressure and
medium temperature
Fluids
Saturated steam
Superheated steam
Recommendation
Calculation of the k
vs
value for steam