EB 8015 EN 8-1
Malfunctions
8 Malfunctions
Read hazard statements, warnings and caution notes in the 'Safety instructions and mea-
sures' section.
8.1 Troubleshooting
Malfunction Possible reasons Recommended action
Actuator and plug stem
does not move on
demand.
Actuator is blocked. Check attachment.
Remove the blockage.
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 ngers 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. Before unblocking the
actuator, release any stored energy in the actuator
(e.g. spring compression). See associated actuator
documentation.
Diaphragm in the actu-
ator defective
See associated actuator documentation.
Signal pressure too low Check the signal pressure.
Check the signal pressure line for leakage.
Jolting movement of the
actuator and plug stem
Packing tightened too
far
Tighten the packing correctly (see information under
'Adjusting the packing' in the 'Testing the installed
valve' section).
Actuator and plug stem
does not stroke through
the entire range.
Signal pressure too low Check the signal pressure.
Check the signal pressure line for leakage.
Travel stop active See associated actuator documentation.
Incorrect setting of
valve accessories
Check the settings of the valve accessories.
Increased ow through
closed valve (seat leak-
age)
Dirt or other foreign
particles deposited be-
tween the seat and
plug.
Shut off the section of the pipeline and ush the
valve.
Valve trim, particularly
with soft seat, is worn.
Replace seat and plug (see the 'Servicing' section)
or contact our after-sales service.
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