Fisher 2500 Series Instruction Manual page 24

Type 2500
FAULT
1. Process wanders or cycles
around set point.
2. Controller/transmitter
controlling off set point or
switching point.
3. Controller/transmitter cannot
attain full output range.
4. Controller/transmitter remains
at full or zero output pressure.
24
Table 6. Troubleshooting Chart for 2500 Series Controller/Transmitters
POSSIBLE CAUSE
1.1 Proportional band or specific
gravity adjustment incorrect or
improperly tuned control loop.
1.2 Supply pressure varying or
incorrect supply pressure setting.
1.3 Sensor not plumb and is in
contact with sidewall or leak in
displacer.
1.4 Relay malfunction.
2.1 Supply pressure not set
correctly.
2.2 Leak in the
controller/transmitter loop.
2.3 Leaking displacer.
2.4 Flapper adjustment.
2.5 Process variable changed.
3.1 Supply pressure not set
correctly.
3.2 Flapper adjustment.
3.3 Process variable changed.
3.4 Relay malfunction
3.5 Leak in the
controller/transmitter loop.
4.1 Supply or output pressure
gauge malfunction.
4.2 Flapper adjustment.
CHECK
Ensure the prestartup procedures
are completed correctly. Tune
control loop.
Use input pressure gauge to
monitor stability. Make sure
regulator IN supply pressure is
within limits.
Check cage vessel and stillwell
installation, or for leaking
displacer.
Check for relay malfunction by
using the testing relay deadband
procedure.
Make sure regulator supply
pressure is set correctly. Make
sure regulator IN supply pressure
is within limits.
Use soap and water to check for
internal and external leaks.
Ensure the displacer is not filling
with process fluid.
Ensure the flapper is not loose on
the torque tube shaft and is
centered on the nozzle.
Ensure the process variable has
not changed from original
calibration settings, or displacer
not designed for specific gravity of
process.
Make sure supply pressure is set
correctly. Make sure regulator IN
supply pressure is within limits.
Ensure the flapper is not loose on
the torque tube shaft and is
centered on the nozzle.
Ensure the process variable has
not changed from original
calibration settings, or from
displacer's designed specific
gravity.
Check for relay malfunction by
using the testing relay deadband
procedure.
Use soap and water to check for
internal and external leaks.
Ensure the pressure gauges are
registering correctly.
Ensure the flapper is not loose on
the torque tube shaft and is
centered on the nozzle.
CORRECTION
If stable control cannot be attained
and all other elements are
functionally correct, examine other
possible causes related to the
controller/transmitter.
Apply correct supply pressure.
Use one regulator per instrument.
Make sure the displacer and
displacer rod hangs freely. Make
sure linkage is tight. Replace
displacer if leaking.
Depress plunger to clean out the
fixed restriction. Replace or repair
relay using the procedure in the
Maintenance section.
Reset the supply regulator
pressure. If the condition occurs
again, rebuild or replace regulator.
Provide a regulator input pressure
within regulator limits.
Replace or repair leaking parts as
necessary.
Refer to sensor maintenance
procedures in the appropriate
sensor instruction manual.
Replace or tighten flapper
assembly as necessary and/or
center flapper on nozzle.
Change process variable back to
original specification or
recalibrate. If necessary, provide
replacement displacer of correct
size and recalibrate.
Reset the regulator pressure. If
problem reoccurs, replace or
rebuild the regulator. Ensure
regulator IN supply pressure is
within limits at all operating levels.
Replace or tighten flapper
assembly as necessary and/or
center flapper on nozzle.
Change process variable back to
original specification or
recalibrate. If necessary, provide
replacement displacer of correct
size and recalibrate.
Depress plunger to clean out the
fixed restriction. Replace or repair
relay using the procedure in the
Maintenance section.
Replace or repair leaking parts as
necessary.
Replace pressure gauges. Use
corrective action given in section 3
of this table.
Replace or tighten flapper
assembly as necessary and/or
center flapper on nozzle.