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8 Malfunctions
Read hazard statements, warnings and caution notes in the 'Safety instructions and mea-
sures' section.
8.1 Troubleshooting
Malfunction
Actuator and plug stem
does not move on
demand.
Jolting movement of the
actuator and plug stem
Actuator and plug stem
does not stroke through
the entire range.
EB 8251 EN
Possible reasons
Actuator is blocked.
Diaphragm in the
actuator defective
Signal pressure too low Check the signal pressure.
Version with adjustable
packing
: packing not
1)
tightened correctly
Signal pressure too low Check the signal pressure.
Travel stop active
Incorrect setting of
valve accessories
Recommended action
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 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. Before unblocking the
actuator, release any stored energy in the actuator
(e.g. spring compression). See associated actuator
documentation.
See associated actuator documentation.
Check the signal pressure line for leakage.
Tighten the packing correctly (see information under
'Adjusting the packing' in the 'Installation' section >
'Testing the installed valve').
Check the signal pressure line for leakage.
See associated actuator documentation.
Check the settings of the valve accessories.
Malfunctions
8-1
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