12
EB 8026 EN
Operation
5
Operation
(e.g. reversing the operating direction etc.)
Refer to the mounting and operating instruc-
tions of the pneumatic actuators:
u
EB 8310 EN for Type 3271
u
EB 8311 EN for Type 3277
6
Maintenance – Replacing
parts
The control valve is subject to normal wear,
especially at the seat, plug and packing. De-
pending on the operating conditions, check
the valve at regular intervals to prevent pos-
sible failure before it can occur.
External leakage can indicate that the pack-
ing is defective or the metal bellows is defec-
tive (in a version with a bellows seal).
If the valve does not close tightly, tight shut-
off may be impaired by dirt stuck between
the seat and plug or by damaged facings.
We recommend removing the parts, cleaning
them, and, if necessary, replacing them with
new ones.
Note:
Suitable seat wrenches and special
tools as well as the associated tight-
ening torques are listed in the docu-
ment
u
EB 029 EN.
Contact your nearest SAMSON sub-
sidiary or the SAMSON After-sales
Service department for information
on suitable lubricants.
WARNING!
−
Before performing any work on the
control valve, make sure the rele-
vant plant section has been depres-
surized and, depending on the
process medium, drained as well.
−
When used at high temperatures,
allow the plant section to cool
down to ambient temperature.
−
Valves are not free of cavities.
Therefore, there might still be resid-
ual medium in the valve. This ap-
plies to valve versions with bellows
seal or insulating section in particu-
lar. We recommend removing the
valve from the pipeline.
−
Before starting any work on the
valve body, disconnect the signal
pressure and remove the actuator.
Removing the actuator from the valve
Note:
When removing an actuator with
"actuator stem extends" fail-safe ac-
tion from a valve, and especially an
actuator with preloaded springs, ap-
ply a signal pressure that is slightly
higher than the lower bench range
value (see actuator nameplate) to the
bottom signal pressure connection so
that the ring nut (8.2) can be un
-
screwed.
1.
Remove the stem connector (7) and un
-
screw the ring nut (8.2).