PNEUMATIC CONTROLLER
SERIES
SG6100
Page: 14
MAR-IN CONTROLS B.V. VAN UTRECHTWEG 8 –10 KRIMPEN A/D IJSSEL THE NETHERLANDS
Tel. + 31 (0)180 - 51 71 51 Fax +31 (0)180 - 51 89 14 [email protected] www.mar-in-controls.com
TROUBLE SHOOTING
DEFECT
Output too high
Output too low
Indication (or
Recording) ir-
regular.
Poor control:
measured value
pointer wanders.
Oscillations in the
Control Loop.
Poor control:
measured value
pointer cycles about
setpoint.
Response speed
too slow.
Measured value
pointer does not
accurately indicate
the measured
value.
PROBABLE CAUSE IN THE CONTROLLER
Controller in the wrong action.
Plugged nozzle.
Nozzle air tube pinched or kinked.
Output air screen plugged.
The flapper does not properly cap the nozzle.
Calibrated orifice (in output relay) clogged.
Controller in wrong action.
Leak around Integral restrictor stem.
Dirty relay stem.
Proportional Band too wide.
Reset time too long.
Friction in the relay valve.
Friction in the controller proportional lever.
Proportional Band too narrow.
Reset time too short.
Output relay defective.
Nozzle partially blocked.
Output air screen plugged.
Calibrated orifice in the output relay dirty.
Measuring element link connected to wrong
point pivot hole of disconnected.
Measuring element out of calibration.
Measuring element damaged.
PROBABLE CAUSE OUTSIDE CON-
TROLLER
Valve undersized.
Valve oversized.
Leak in output line or valve actuator.
Low air supply pressure.
Obstructed or partially obstructed
tubing between the process and the
primary measuring element.
Air pockets in the tubing on the process
side.
Valve stem sticking.
Disturbances from other processes
affecting the controlling medium.
Tubing between the process and the
primary measuring element partially
obstructed.
Process sensing line plugged or
broken.
