Conversion Work; Reversing The Direction Of Action (Fail-Safe Action) - Samson 3371 Mounting And Operating Instructions

Servicing and conversion

9.5 Conversion work

See Fig. 9-1 and Fig. 9-2
9.5.1 Reversing the direction
of action (fail-safe ac-
tion)
The direction of action (and fail-safe action)
of pneumatic actuators with 120 cm² actua-
tor area can be changed.
The direction of action (and fail-safe action)
of the pneumatic actuator with 350 cm² ac-
tuator area is determined at the ordering
stage and cannot be changed. If necessary,
contact our after-sales service.
The fail-safe action is indicated on the name-
plate by a symbol:
Actuator stem extends (FA)
Actuator stem retracts (FE)
a) Reversal of the direction of
action from stem extends to
stem retracts for 120 cm² ac-
tuator area
1. Lift off the top diaphragm case (A16)
and remove springs (A10).
2. Pull the actuator stem (A3) together with
the diaphragm plate (A14), diaphragm
(A18) and diaphragm plate (A13) out of
the bottom diaphragm case (A2).
3. Unscrew the collar nut (A26).
9-8
4. Remove the diaphragm plate (A14), dia-
phragm (A18) and diaphragm plate
(A13) from the actuator stem (A3) and
place them back on again in the reverse
order.
5. Tighten the collar nut (A26). Observe
tightening torques.
6. Apply a suitable lubricant to the actuator
stem (A3).
7. Place the springs (A10) in the bottom di-
aphragm case (A2), centering them in
the intended recesses.
8. Place the actuator stem (A3) together
with the diaphragm plate (A14), dia-
phragm (A18) and diaphragm plate
(A13) in the bottom diaphragm case
(A2). Make sure that the radial shaft seal
(A40) is not damaged.
9. Place on the top diaphragm case (A16).
10. Fasten the top and bottom diaphragm
cases (A16, A2) together using the nuts
(A24) and bolts (A22). Observe tighten-
ing torques.
The actuator springs, which now push
against the diaphragm plate from below,
cause the actuator stem to retract. The
signal pressure is connected to the top
connection (S) on the top diaphragm
case. As a result, the actuator stem ex-
tends opposing the spring force as the
signal pressure increases.
11. Affix a new nameplate with changed
symbol and new configuration ID to the
actuator.
EB 8317 EN