Operation; Reversing The Operating Direc- Tion (Fail-Safe Action) - Samson 3277 Mounting And Operating Instructions

Reversing the operating direction (fail-safe action)

2 Operation

Note!
It is important for a troublefree operation of
the actuator that the vent plug (3) is not
blocked in the Type 3277 Actuator.
Make sure in versions with a handwheel
that the plug stem can move freely when the
valve is being positioned by the pneumatic
actuator by moving the handwheel into a
neutral position.
2.1 Reversing the operating direc-
tion (fail-safe action)
The operating direction and the fail-safe ac-
tion in pneumatic actuators can be
changed. Prior to proceeding, you must
remove the actuator from the valve.
The fail-safe action is designated by a sym-
bol on the nameplate.
Actuator stem extends or
Actuator stem retracts
Warning!
To disassemble an actuator with pre-
loaded springs (recognizable by the
long bolts on the diaphragm cham-
bers), always undo the short bolts
first and then unthread the long
bolts slowly and evenly until the actu-
ator springs are fully decompressed.
6
EB 8311 EN
2.1.1 Standard actuator
Reversing the fail-safe action "actuator
stem extends" to "actuator stem retracts"
Note!
The operating direction of actuators with
2
700 cm (travel = 30 mm) and spring
ranges - 0.2 to 1 bar, 0.4 to 2 bar and 0.6
to 3 bar - that are mounted to valves with
15 mm travel, can be only changed when
the standard actuator stem is replaced by
an actuator stem (order no. 0290-5266)
that is 20 mm shorter.
These actuators are preloaded by approx.
50 % on mounting them to the valve due to
the varying travels.
This means the bench range (spring range)
of 0.2 to 1 bar results in a signal pressure
range of 0.6 to 1 bar; 0.4 to 2 results in
1.2 to 2 bar and 0.6 to 3 results in 1.8 to
3 bar.
The signal pressure range is recorded on
the nameplate when the actuators have
been preloaded on mounting them to the
valve.
1. Unthread the nuts and remove the bolts
(9) from the diaphragm cases.
2. Lift off the top diaphragm case and
remove the springs (6).
3. Pull the actuator stem (2) with dia-
phragm plate (7) and diaphragm (8)
out of the yoke (10).
4. Unscrew nut (1), while holding the nut
(1.1) stationary with a suitable tool or
clamp the actuator stem.
Caution: Proceed carefully to avoid da-
maging the seals of the actuator stem.