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Servicing
Inspection and testing
Check the valve's seat leakage.
Check the valve for external damage
(e.g. corrosion).
Check the valve accessories to ensure
they are mounted properly.
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
the 'Decommissioning' section).
3. Remove the actuator from the valve. See
associated actuator documentation.
Note
To remove a pneumatic actuator with "stem
extends" fail-safe action and/or with pre-
9-4
Action to be taken in the event of a negative result:
Shut off the section of the pipeline and flush the valve to re-
move any dirt and/or deposited foreign particles between
the seat and plug.
Repair any damage immediately. If necessary, put the con-
trol valve out of operation (see the 'Decommissioning' sec-
tion).
Tighten the connections of the valve accessories.
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
actuator or valve.
Before trying to unblock the actuator or plug stem,
disconnect and lock the pneumatic air supply as well as the
control signal. Disconnect the supply voltage. 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 the 'Decommis-
sioning' section). Identify the cause for the malfunction and
rectify it (see the 'Troubleshooting' section).
loaded springs, a certain signal pressure
must be applied to the actuator (see associ-
ated actuator documentation). Afterwards,
the signal pressure must be removed and the
air supply disconnected again and locked.
Tip
We recommend removing the valve from the
pipeline before performing any service work
(see the 'Removal' section).
The following service work can be per-
formed after preparation is completed:
EB 8113/8114 EN
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