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7. Maintenance Procedure
7.1 Troubleshooting (Refer to "7.5 Exploded drawing".)
Problem
Pressure does not
reach the desired
value.
Reduced pressure
raises above than
the specified value.
Abnormal noise is
heard.
Cause
1. Incorrect pressure is being used.
2. Insufficient operating air pressure.
3. Screen [15] is clogged.
4. Main diaphragm [11] is damaged.
5. Orifice of tee [33] is clogged.
6.Pilot valve [17] and pilot valve seat
[18] are clogged with foreign
matter, scales, etc.
7. Sensing pipe is clogged.
8. Nominal size is too small for the
specifications.
9. Pressure is not adjusted correctly.
10. Wrong installation with tee [33]
11. Strainer installed before pressure
reducing valve is clogged.
12. Pressure gauge is faulty.
1. Operating air pressure too high.
2. The relief of the operating air
pressure is small.
3. Foreign matter exists between
main valve [11] and main valve
seat [12], or scratches exist.
4. Foreign matter exists between
pilot valve and pilot valve seat, or
scratches exist.
5. Orifice of tee [33] is clogged.
6. Reduced pressure is not adjusted
correctly.
7. Foreign substances stuck
between the spindle [8] and the
guide [9].
8. Trap is not provided for dead-end
line.
9. By-pass valve is leaking.
1. Orifice of tee [33] is clogged.
2. Nominal size is too large for the
specifications.
3. Pressure reducing ratio is too
large.
4. Drainage problem is caused.
5. A quick operating valve installed
near the product.
6. Outlet pipe diameter is too small.
7. No or too much operating air
pressure relief.
1. Correct the pressure.
2. Increase the operating air
pressure to the desired set
pressure.
3. Disassemble and clean the
screen.
4. Replace the main diaphragm.
5. Remove the tee and clean it.
6. Disassemble pilot valve assembly,
and clean it.
7. Disassemble and clean it.
8. Change the nominal size
appropriately.
9. Observe the adjustment
procedures and readjust pressure.
10. Install the tee whose slit should
be faced upward.
11. Disassemble and clean it.
12. Replace it.
1. Decrease the operating air
pressure.
2. Release a little of the operating
air pressure with a needle valve,
etc. (Refer to "5.4 Piping
example".)
3 Disassemble and remove the
foreign matter. When any
scratches are identified, lap the
main valve and main valve seat.
Change the parts if scratches still
exist after lapping.
4. Disassemble the pilot valve
assembly, and clean or replace it.
5. Remove the tee and clean it.
6. Observe the adjustment steps
and readjust pressure.
7. Disassemble the product and
remove the foreign substances.
8. Install a trap.
9. Repair or replace it.
1. Remove the tee and clean it.
2.Change the nominal size
appropriately.
3. Reduce pressure in two stages.
4. Install a trap.
5. Place the quick operating valve
more than 3 meters away from the
product.
6. Select a pipe size that will
produce a flow velocity of 30m/s
or less.
7. Set correctly.
-15-
Solution
■EPDT-098a■
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