172-65587MA-02 (CV-COSR Pneumatic Control Valve) 3 Jun 2019
19
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.
CAUTION
When the product fails to operate properly, use the following table to locate the
cause and remedy.
Problem
Cause
Diagnosis
Remedy (Countermeasure)
Valve Leakage
The pressure of the
air supply to the
positioner is too high
Check the pressure of the air
supply to the positioner and
confirm product specifications
Adjust the pressure of the air
supply for the positioner to
match the pressure in the
product specifications
The positioner’s zero
point is miscalibrated
Check the actuator air supply
pressure (on the positioner’s
pressure gauge) when the
operation signal is at 4 mA
If the pressure on the pressure
gauge is elevated (not 0
MpaG (0 psig)), adjust the
positioner’s zero point
The inlet pressure for
the valve is too high
Check the inlet pressure for
the valve
Operate at an inlet pressure of
1.0 MPaG (150 psig) or less
The valve plug and
valve seat are off-
center
Move the valve plug & stem up
and down and check to see if it
catches
Reassemble the valve bonnet
section correctly
There is a problem
with the sealing
surfaces of the valve
plug and valve seat
Check the valve plug and
valve seat
Replace with a new valve plug
& stem and valve seat
The valve does
not travel
beyond a certain
point
The bellowphragm in
the actuator is broken
Check to see if a large amount
of air is leaking from the
exhaust tap
Replace with a new positioner/
actuator unit
[Check to make sure that the
valve is not operating
(traveling) too often and that
the ambient temperature is not
too high]
The positioner’s
internal parts are
broken
(The diaphragm is
cracked, etc.)
Check to see if any unusual
noise is coming from the
positioner
Replace with a new positioner/
actuator unit
[Check to make sure that the
valve is not operating
(traveling) too often and that
the ambient temperature is not
too high]
There is insufficient
air supply pressure to
the positioner
Check the pressure of the air
supply to the positioner and
refer to product specifications
Adjust the supply air pressure
for the positioner
(Confirm product
specifications)
Malfunction of the
signal system
Check to make sure the
controller is emitting a 4 to 20
mA signal and that the wires
are not disconnected, etc.
Inspect the controller and
repair the signal wiring if
necessary
Continued on next page
