Design And Principle Of Operation - Samson 42-10 Mounting And Operating Instructions

3 Design and principle of oper-
ation
Î See Fig. 3-1 and Fig. 3-2
The regulator prevents flowback from directly
connected systems. Observe the pressure
and temperature limits on the nameplate.
The regulator is open, provided the upstream
pressure is at least 0.2 bar/3 psi greater
than the downstream pressure. It closes auto-
matically when the downstream pressure ris-
es to or above the value of the upstream
pressure.
The regulator basically consists of the valve
(1) with seat (2) and plug (3) as well as the
opening actuator (10) with two diaphragms
(11).
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 (3 psi/5 psi)
1)
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
be greater than the downstream pressure p
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 supply network.
DN 200 and 250/NPS 8 and 10 version
1)
EB 3009 EN
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 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
, the valve
1)
diaphragm.
A pressure switch (18) can be optionally
mounted to the actuator to trigger an alarm.
must
1
.
2

Design and principle of operation

3-1