Malfunctions; Troubleshooting - Samson 3251 Mounting And Operating Instructions

8 Malfunctions

Read hazard statements, warnings and caution notes in the 'Safety instructions and mea-
sures' chapter.

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 full
range.
Increased flow
through closed valve
(seat leakage)
EB 8052 EN
Possible reasons
Actuator is blocked.
Diaphragm in the actuator
defective
Signal pressure too low
Version with adjustable
packing : packing
2)
tightened too far
Signal pressure too low
Travel stop active
Incorrect setting of valve
accessories
Dirt or other foreign
particles deposited between
the seat and plug.
Valve trim, particularly with
soft seat, is worn.
Recommended action
Put the control valve out of operation (see the
'Decommissioning' chapter) and 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.
Check the signal pressure line for leakage.
Tighten the packing correctly (see section
'Adjusting the packing' in the 'Installation'
chapter > 'Testing the installed valve').
Check the signal pressure.
Check the signal pressure line for leakage.
See associated actuator documentation.
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'
chapter) or contact our after-sales service.
Malfunctions
8-1