User Manual

8/12
Siemens 2-port seat valves PN25 with flanged connection CM1N4373en
Building Technologies 15.11.2010
Example
given saturated steam 151.8 °C
p
1
= 500 kPa (5 bar)
m

= 460 kg/h
pressure ratio = 30 %
saturated steam 151.8 °C
p
1
= 500 kPa (5 bar)
m

= 460 kg/h
pressure ratio = 42 %
(supercritical permitted)
required k
vs
, valve type k
vs
, valve type
procedure
100
p30
pp
1
13


)bar5.3(kPa350
100
50030
500p
3



h/m83.81
)350500(350
460
4.4k
3
vs


 h/m09.81
500
460
8.8k
3
vs

selected k
vs
= 10 m
3
/h  VVF52.25-10G k
vs
= 8 m
3
/h  VVF52.25-8G
Notes
We recommend installation in the return pipe, as the temperatures in this pipe are lower
for applications in heating systems, which in turn, extends the stem sealing gland's life.
In open circuits the valve plug may seize as the result of scale deposits. In these
applications, only the most powerful SKD.. or SKB.. actuators should be used. Further
the valve should be exercised at regular intervals (two to three times per week). A
strainer MUST be fitted at the valve inlet
Ensure cavitation free flow (refer to page 6).
To ensure the reliability of th
e valve, we recommend the fitting of a strainer at the valve
inlet even in closed circuits.
For media below 0 °C, use the electric stem heating element to prevent the valve stem
from freezing in the sealing gland. For safety reasons, the stem heating element has
been designed for AC 24 V / 30 W operating voltage.
The use of these valves for steam is subject to specific parameters:
Observe diagram for steam on page 7 and "Technical data" on page 10!
Both valve an
d actuator can easily be assembled at the mounting location. Neither
special tools nor adjustments are required.
The valve is supplied with Mounting Instructions 74 319 0509 0.
90°
4716Z16
90°
Engineering
Mounting
Orientation