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7.1 Troubleshooting (Refer to "7.5 Exploded drawing")
Trouble
Reduced pressure of
desired level is not
obtained.
Abnormal pressure
rises at the outlet.
Abnormal sound.
Unstable operation.
● Most of problems at pressure reducing valve is caused by foreign matter and scales in the piping. Be
careful sufficiently.
● Phenomenon like valve trouble happens by pressure gauge failure, bypass valve leakage, forgetting
to close bypass valve or strainer clog. Check the above troubleshooting and take a proper remedy
or prevention.
● Please contact us if you cannot judge whether damaged parts need to be replaced or not.
7. Maintenance Procedure
Cause
1. Working pressure is improper.
2. Insufficient operating air pressure.
3. The main diaphragm [11] is
damaged.
4. The sensing pipe is clogged.
5. The nominal size of the product is
too small for the specifications of
the system.
6. Incorrect pressure adjustment.
7. The strainer on the inlet side of the
product is clogged.
8. Trouble with the pressure gauge.
1. Operating air pressure too high.
2. Foreign substances stuck
between the main valve [5] and
the main valve seat [6], or
scratches on them.
3. Incorrect pressure adjustment.
4. Foreign substances stuck between
the spindle [8] and the guide [9].
5. Trap is not provided on a dead-end
line.
6. Bypass valve is leaking.
1．Nominal size is too large for the
specifications.
2. Too much high-pressure reduction
ratio.
3. Condensate-induced problem.
4. A quick operating valve installed
near the product.
5. Outlet pipe diameter is too small.
6. No or too much operating air
pressure relief.
1. Correct the working pressure.
2. Increase the operating air pressure to the
desired set pressure.
3. Disassemble and replace it.
4. Disassemble and clean it.
5. Replace the product of proper nominal
size.
6. Set correctly (refer to "6.2 Adjusting
procedure").
7. Disassemble and clean it.
8. Replace the pressure gauge.
1. Decrease the operating air pressure.
2. Disassemble the product and remove the
foreign substances. Conduct lapping if
scratches are found. If the scratches still
exist, please contact us.
3. Set correctly (refer to "6.2 Adjusting
procedure").
4. Disassemble the product and remove the
foreign substances.
5. Install a trap device.
6. Repair or replace it.
1．Change the nominal size appropriately.
2. Use a two-stage pressure reduction.
3. Install a trap device.
4. Place the quick operating valve more than
3 meters away from the product.
5. Select a pipe size so that flow velocity can
be 30 m/s or less.
6. Set correctly. (refer to "6.2 Adjusting
procedure").
14
Remedy
EPDT-021a
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