14
Troubleshooting
When disassembling or removing the product, wait until the internal
pressure equals atmospheric pressure and the surface of the product has
cooled to room temperature. Disassembling or removing the product
when it is hot or under pressure may lead to discharge of fluids, causing
burns, other injuries or damage.
Installation, inspection, maintenance, repairs, disassembly, and adjustment should
be done only by trained maintenance personnel.
When the product fails to operate properly, use the following table to locate and
remedy the cause.
Problem
Cause
Remedy
Air supply press. might be too
high (Air to open type)
Readjust the air supply press.
Air supply press. might be too
low (Air to close type)
Readjust the air supply press.
Zero point might be moved
Readjust the zero point
Primary press. of control
valve might be too high
Check the system
Plug or valve seat might be
worn or dirty
Clean parts or replace
Bypass shut-off valve might
be leaking
Check the shut-off valve
Valve Leak
Plug stem can not move
smoothly
Replace parts or reassemble
the bonnet
External leakage from
stuffing box
V-ring or stem might be worn
or dirty
Clean parts or replace
Hunting or chattering of the
valve
Signal from the controller
might be not good
Check the controller
(especially PID)
Diaphragm might be
deformed or broken
Replace the parts
Can not open or close form
proper point
Air supply press. might be too
low
Readjust the air supply press.
Signal from the controller
might be not good
Check the controller and
signal line
No air supply
Check the air supply
No operate at all
Supplied air might contain
dust, water, or oil
Replace the actuator unit and
install better air filer and dryer
CAUTION
The control valve is not shut-off valve, therefore it cannot always shut-
off completely.
