Versions; Additional Fittings - Samson 3241-1-Gas Mounting And Operating Instructions

Design and principle of operation
Fail-safe action
The fail‑safe position depends on the actua‑
tor used. See associated actuator documen‑
tation.
Depending on how the compression springs
are arranged in the SAMSON Type 3271
and Type 3277 Pneumatic Actuator, the
valve has one of two different fail‑safe posi‑
tions:
− Actuator stem extends (FA)
When the signal pressure is reduced or
the air supply fails, the springs move the
actuator stem downward and close the
valve. The valve opens when the signal
pressure is increased enough to over‑
come the force exerted by the springs.
− Actuator stem retracts (FE)
When the signal pressure is reduced or
the air supply fails, the springs move the
actuator stem upwards and open the
valve. The valve closes when the signal
pressure is increased enough to over‑
come the force exerted by the springs.
Note
The "actuator stem extends" direction of ac-
tion is only permitted for the Type 3241G
Valve in valve class D (see Table 3-3).

3.1 Versions

Actuators
Î To select a suitable actuator, see Table
3‑3 (valve class D).
3-4

3.2 Additional fittings

Strainer
Install a strainer or a central strainer facility
upstream of the valve body. It prevents solid
particles in the process medium from dam‑
aging the valve.
Note
For special versions made of A216 WCC or
A351 CF8M in Class 300: as a DIN version
of the Type 2 NI Strainer is only available, a
central strainer facility must be installed
when an ANSI version is used.
Insulation
Control valves can be insulated to reduce
heat energy transfer.
Refer to the instructions in the 'Installation'
section.
Test connection
Versions with bellows seal fitted with a test
connection (G ) at the top flange allow the
1 /
8
sealing ability of the bellows to be moni‑
tored.
Safety guard
For operating conditions that require in‑
creased safety (e.g. in cases where the valve
is freely accessible to untrained staff), a safe‑
ty guard must be installed to rule out a crush
hazard arising from moving parts (actuator
and plug stem). Plant operators are responsi‑
ble for deciding whether a guard is to be
used. The decision is based on the risk posed
by the plant and its operating conditions.
EB 8020 EN