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Servicing
Inspection and testing
Check to ensure that the actuator and
plug stem move smoothly.
If possible, check the valve's fail-safe
position by briefly interrupting the air
supply.
9.2 Preparing the valve for
service work
1. Lay out the necessary material and tools
to have them ready for the service work.
2. Put the control valve out of operation (see
section 10).
Tip
We recommend removing the valve from the
pipeline before performing any service work
(see section 11).
The following service work can be per-
formed after preparation is completed:
− Replace the body gasket. See sec-
tion 9.4.1.
− Replace the packing (see section 9.4.2)
− Replace the seat and plug (see sec-
tion 9.4.3)
40
Action to be taken in the event of a negative result:
Unblock a blocked actuator and plug stem.
WARNING! A blocked actuator or plug stem (e.g. due to
seizing up after remaining in the same position for a long
time) can suddenly start to move uncontrollably. Injury to
hands or fingers is possible if they are inserted into the ac-
tuator or valve.
Before trying to unblock the actuator or plug stem, discon-
nect and lock the pneumatic air supply as well as the con-
trol signal. Before unblocking the actuator, release any
stored energy in the actuator (e.g. spring compression). See
associated actuator documentation.
Put the control valve out of operation (see section 10). Iden-
tify the cause for the malfunction and rectify it.
9.3 Installing the valve after
service work
1. Remount the actuator if it has been re-
moved. See associated actuator docu-
mentation and section 5.
2. Adjust lower or upper signal bench
range. See associated actuator docu-
mentation.
3. If the valve has been removed, re-install
the valve into the pipeline (see section 5).
4. Put the control valve back into operation
(see section 6). Observe the requirements
and conditions for start-up or putting the
valve back into operation.
EB 8822 EN
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