７．Cause & Counter Measure Of Malfunction
Condition Possible Cause Countermeasure
Outlet side
pressure increase
The valve body have plenty of air Please relief the air out of the
valve body.
Refer to 5. Operation Manual.
Foreign Particles stuck in the valve
(Stick at seat ring, shield ring, Pilot valve's
seat ring and shield ring)
Remove the foreign particles.
Part's Damage
(Seat ring, shield ring, Pilot valve's seat ring
and shield ring)
Exchange the main body shield
ring, and pilot valve shield ring.
PRV main body seat ring, pilot
valve body seat ring part if
serious damage, please exchange
the part.
The valve body's stem can't operate
smoothly.
(Stem, seat, guide bush)
Use cloth file to filing the stem,
make it smooth to operate.
Pilot valve's diaphragm damaged. Exchange the part
Strainer clogging Clean the strainer mesh
Outlet side
pressure does not
rise
The valve body's stem can't operate
smoothly.
(Stem, seat, guide bush)
Use cloth file to filing the stem,
make it smooth to operate.
Wrong selection of the sizes
(Nominal diameter too small)
Reconfirm the specification and
change the nominal diameter
sizes.
Piping resistance too big Checking the piping
Operation Failure
(Pulsation,
vibration,
pressure
unstable)
Air pocket in the piping Proceed to relief the air, or install
the air vent
Wrong selection of the sizes Reconfirm the specification and
change the nominal diameter
sizes.
Pressure reduction ratio too big Do two steps pressure reducing
Poor adjustment of the needle valve Small opening of the needle
valve, the disc assembly of the
PRV body easy to operate and
also insensitivity easily.
If opening too big, the disc
assembly of the valve body,
operation easily become
unstable and acutely.
