Samson 2780-1, Монтаж и эксплуатация, Страница: 35 / 52

EB 5840 EN 8-5
Servicing and conversion work
10. Fasten the top and bottom diaphragm
cases (A42, A40) together with the nuts
and bolts.
8.5 Conversion work
Refer to Fig. 8‑1
8.5.1 Reversing the direction
of action (fail-safe
action)
The direction of action (and fail‑safe action)
of pneumatic actuators can be changed. The
fail‑safe action is indicated on the nameplate
by a symbol:
Actuator stem extends
Actuator stem retracts
a) Reversal of the direction of
action from stem extends to
stem retracts
1. Lift off the top diaphragm case (A42)
and remove springs (A25).
2. Pull the actuator stem (A1) together the
diaphragm plate (A39), diaphragm
(A48), metal plate (A38) and bushing
(A46) out of the bottom diaphragm case
(A40).
3. Completely unscrew the collar nut (A53),
while holding the actuator stem (A1) sta‑
tionary using a suitable tool which can‑
not damage the sealing.
4. Remove the diaphragm plate (A39) to‑
gether with the diaphragm (A48) and
metal plate (A38) from the actuator stem
(A1) and place them back on again
turned over.
5. Tighten the collar nut (A53).
6. Apply a suitable sealant and lubricant to
the actuator stem (A1).
7. Turn over the top diaphragm case (A42)
and place the actuator stem (A1) togeth‑
er with the ready‑assembled diaphragm
parts inside it.
8. Slide the bushing (A46) over the actuator
stem (A1).
9. Place the springs (A25) in the top dia‑
phragm case (A42), centering them in
the intended recesses.
10. Place on the bottom diaphragm case
(A40).
11. Fasten the top and bottom diaphragm
cases (A42, A40) together with the nuts
and bolts.
12. In Type 2780‑1, remove the vent plug
(A20) and screw it into the bottom signal
pressure connection (S
FA
).
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
FE
) on the top diaphragm
case. As a result, the actuator stem ex‑
tends opposing the spring force as the
signal pressure increases.