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Maintenance and troubleshooting
Table 1: Troubleshooting
Malfunction
Possible reasons
Insufficient pressure pulses on the actua-
tor diaphragm
Leak between seat and plug due to wear
Differential
pressure
exceeds the
Pressure tapped at the wrong place.
adjusted set
point
Diaphragm defective
Valve too large for control task
Differential
pressure
Valve or K
drops far be-
low the ad-
Safety device, e.g. pressure limiter, has
justed set
been triggered
point
Valve too large
Control loop
No damping of the pulses as the restric-
hunts.
tion in the screw fitting of the actuator is
too large or is missing.
14
coefficient too small
VS
Recommended action
Clean the control line and the screw joint
with restriction.
Disassemble the regulator and replace
damaged parts.
Reconnect control lines at a different
place. Do not tap pressure at pipe bends
or necks.
Replace the diaphragm (see section 7.1).
Recalculate K
coefficient. Contact
VS
SAMSON.
Check valve sizing. Install larger valve, if
necessary.
Check plant. Unlock safety device.
Check valve sizing. Select valve with
smaller K
coefficient, if necessary.
VS
Install suitable needle valve in the control
line at the actuator. Close this needle
valve until the control loop becomes
stable. Do not close the needle valve
completely!
EB 3003 EN
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