Azbil Corporation
36
Model
KFPA
,
KFTA
- Field Mount type Pressure Indicating Controllers
6-5: Troubleshooting
For troubleshooting the instrument, see the following table. For adjustment, refer to the preceding
chapter.
Symptom
Probable cause
Troubleshooting
Pilot relay
whines.
Valve sheet is stained.
Remove pilot relay, and clean valve sheet.
Little or no
control
pressure is
delivered.
Supply air pressure is off or
below 140 kPa {1.4 kgf/cm²}.
Restriction is clogged.
Provide proper supply pneumatic pressure.
Remove restriction and clean it.
Restriction is not correctly set. When no transmitter is used, restriction is provided
with blind plug. Reattach it to correct position.
Correctly set restriction(s) and plug depending on
whether the instrument has transmitter or not.
Filter is badly stained.
Replace filter
There is leakage in nozzle
circuit of indicating control
section.
After making sure that O-rings are properly
attached, firmly tighten the controller unit and
restriction.
There is leakage or choking in
A/M transfer circuit. (When
A/M transfer switch is
provided.)
Remove manual control unit and make sure that
circuit is correct and that O-rings of connecting
section are properly attached. Then, firmly tighten
the unit.
There is leakage from pilot
relay diaphragm.
Remove pilot relay, check diaphragm and, in case
of leakage, replace diaphragm.
Control
pneumatic
pressure is too
high
Nozzle of indicating control
section is clogged.
Clean nozzle.
Restriction screw of indicating
control section is not in firm
contact with sheet surface.
Tighten so that sheet surface of restriction screw is
contacted with the manifold.
Valve sheet of pilot relay is
stained.
Remove pilot relay and clean valve sheet.
Input offset in
indication is
large.
Set point pointer or measuring
pointer is shifted.
Readjust deviation generating mechanism and
indicating mechanism. (See “5: Calibration and
adjustment”.)
Control mechanism is not
properly adjusted.
(Proportional band is not
properly balanced.)
Adjust the balancing of control mechanism. (See
“5: Calibration and adjustment”)
Reset rate is
abnormal or
ineffective.
Needle or sheet is damaged.
Use new needle assembly.
Dial attaching screw is noose. Set dial in correct position and fix it firmly with
screw.
Air is leaking from gasket.
Firmly fix it to the base.
Manual control
pressure does
not rise.
Supply pneumatic pressure is
not applied or below 140 kPa
{1.4 kgf/cm²}.
Supply proper supply air pressure.
