6
EB 3009 EN
Design and principle of operation
The medium flows through the valve in the
direction indicated by the arrow. The posi-
tion of the valve plug (3) determines the dif-
ferential pressure over the cross-sectional ar-
ea released between the plug and seat (2).
At a differential pressure of
0.2 bar/3.0 bar
1)
(3 psi/5 psi)
1)
, the valve
begins to open; at 0.35 bar/0.55 bar
(5 psi/7 psi), the valve is completely open.
At this point, the upstream pressure p
1
must
be greater than the downstream pressure p
2
.
The regulator closes automatically when the
downstream pressure rises to or above the
value of the upstream pressure. The standard
plug is soft-seated to ensure tight shut-off
and to prevent backflow from the plant into
the medium supply network.
The mounted control lines (14) transmit the
upstream and downstream pressures to the
actuator.
The actuator with two diaphragms (11)
offers increased safety and reliability of
functions. The operating diaphragm for
upstream pressure (11.1) is connected to the
valve input pressure, whereas the operating
diaphragm for downstream pressure (11.2)
is connected to the valve output pressure. A
bore with a mechanical diaphragm rupture
indicator (12) is located in the intermediate
ring located between the two diaphragms.
The pressure of response of the diaphragm
rupture indication is approximately
1.5 bar/22 psi. In the event of a diaphragm
rupture, the pressure in the space between
the two operating diaphragm starts to
1)
DN 200 and 250/NPS 8 and 10 version
1
Valve body
2
Seat
3
Plug
4
Plug stem
5
Threaded connection for diaphragm
actuator
6
Actuator stem
7
Diaphragm stem
10
Actuator housing
11
Two diaphragms
11.1 Operating diaphragm for upstream
pressure
11.2 Operating diaphragm for downstream
pressure
12
Diaphragm rupture indicator
13
Set point springs
14
Control line 8x1 mm
15
Spacer bushing
16
Housing bolts (two long bolts opposite each
other, DN 15 to 25/NPS ½ to 1 only)
16.1 Top housing bolts
16.2 Bottom housing bolts
17
Diaphragm plate nut (outer)
17.1 Diaphragm plate nut (inner)
18
Pressure switch (optional)
19
Compensation chamber (optional)
20
Filler plug
increase. This causes the pin in the
diaphragm rupture indicator to be pushed
outwards and a red ring appears, indicating
the diaphragm rupture. The intact operating
diaphragm takes on the control task of the
ruptured diaphragm.
A pressure switch (18) can be optionally
mounted to the actuator to trigger an alarm.