Malfunctions; Troubleshooting - Samson 3351 Mounting And Operating Instructions

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.
Actuator and plug stem
does not stroke through
the full range.
Increased flow through
closed valve (seat
leakage)
EB 8039 EN
Possible reasons
Actuator is blocked.
Diaphragm defective
Signal pressure too low Check the signal pressure.
Signal pressure too low Check the signal pressure.
Incorrect setting of
valve accessories
Dirt or other foreign
particles deposited
between the seat and
plug.
Valve trim is worn out.
Facing is damaged.
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. Relieve the compression
before unblocking the actuator. See 'Relieving the
spring compression in the actuator' in the 'Removal'
section.
Replace diaphragm (see the 'Servicing' section) or
contact our after-sales service.
Check the signal pressure line for leakage.
Check the signal pressure line for leakage.
Check the settings of the valve accessories.
Shut off the section of the pipeline and flush the
valve.
Replace seat and plug (see the 'Servicing' section)
or contact our after-sales service.
Malfunctions
8-1