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Self-Operated Pressure Controller
Steam Pressure Reducing Valve
◘ Application
Pressure controller for set points from 0.8 to 16 bar. Valve size DN 15 to 100
nominal pressure PN 16 or 25 for steam
up to 3500C. The Valve closes when the
downstream pressure rises.
The type 39-2 Steam Pressure Reducing
Valve controls the downstream pressure
to keep the set point. The controller has
the following special features:
- Self-operated P-controller requiring
no auxiliary energy.
- Actuator and springs are exchangeable
- Tight closing single-ported valve with upstream pressure balancing and
frictionless plug stem seal by means of stainless steel bellows. All parts
in contact with the medium are free of
non-ferrous metal.
◘ Versions
Type 39-2. steam pressure reducing valve
consisting of: Control valve with valve body
In cast iron or cast carbon steel. Actuator (with EPDM
diaphragm) with condensation chamber and screw joint for
steam temperatures up to 350 °C.
◘ Mode of Operation (Fig. 2)
The direction of steam through the valve is shown by the
arrow. The position of the plug and hence the free area
between the plug (3) and seat (2) control the flow rate. The
downstream pressure (P2) that is to be controlled is
transmitted via a control line to the diaphragm (13) and
converted into a positioning force. This force is used to
adjust the positioning of the valve plug (3) according to the
force of the springs. The positioning force is controllable by
means of the set point adjustment (6).
This system is equipped with a
stainless steel bellows (4.1). The upstream pressure (Pi)
acts on the outer surface of the bellows. In this way the
forces those are acting on the plug (3) are balanced and the variety of up
stream pressure is unaffect on the adjusting set point downstream pressure.
1 Valve body
2 Seat
3 Plug
4 Bellows housing
4.1 Balancing bellows
5 Plug steam
6 Set point adjustment
7 Operating spring
8 Flange
9 Bracket
10 Actuator
11 Actuator Stem
13 Operating diaphragm
I 7 Control line connection (screw joint with orifice plate)
20 Condensation chamber
21 Filling plug
25 Feed back system |
Figure 2: Type 39-2 |
◘ Technical Data. All
pressure stated in bar (gauge) - Table 1
| Nominal size DN |
15-50 |
65-80 |
100 |
| Nominal pressure PN |
16 or 25 (acc. To DIN 2401) |
| Temperature ranges-see
pressure-Temperature-Diagram |
| Max. allowable
differential pressure ∆P |
25 bar |
20 bar |
16 bar |
| Set. point range |
0.8 ... 2.5; 2 ... 5; 4.5 ...
10; or 8 ... 16 |
◘ Material (WN = DIN Material Number)
- Table 2
| Nominal size DN |
PN 16 |
PN 25 |
| Max. Permissible temp. |
300 °C |
350 °C |
| Body |
Cast iron GG-25
WN 0.6025 |
Cast steel GS-C 25
WN 1.619 |
| Seat and plug |
Stainless steel WN 1.4006 |
| Metal bellows |
Stainless steel WN 1.4571 |
| Body gasket |
Graphite on Metal Core |
| Actuator |
Diaphragm case. Sheet steel St 37-2 |
| Diaphragm |
EPDM with fabric reinforcement |
| Permissible ambient temperature: 80
°C |
Pressure-Temperature Diagram (according to
DIN2401)
The permissible pressure, differential
pressure and temperature are determined by the pressure temperature diagram.
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