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EPDT-023c
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7. Maintenance Procedure
7.1 Troubleshooting
Problem
Causes
Solutions
Primary pressure
increases
1. Nominal size is too small for these
specifications.
2. Incorrect adjustment.
3. Poor sliding of internal parts.
4. Strainer is clogged.
5. Pressure gauge malfunction.
6. The conductor pipe [25] is clogged
with foreign matter.
1. Replace with the correct nominal sized item.
(Refer to the “4. Nominal Size Selection
Method”.)
2.
Re-adjust according to the adjustment
procedure. (Refer to the “6.2 Adjustment
Procedure”.)
3. Disassemble and clean.
4. Disassemble and clean.
5.
Replace the pressure gauge.
6. Disassemble and clean.
Primary pressure
drops
1. Foreign matter is embedded in the
valve [9] and/or valve seat [8], or else
scratches exist.
2. Incorrect adjustment.
3. Poor sliding of internal parts.
4.
By-pass valve is leaking.
5. Diaphragm [11] or O rings is broken.
1. Disassemble and clean. If scratches exist,
replace them.
2. Re-adjust according to the adjustment
procedure. (Refer to the “6.2 Adjustment
Procedure”.)
3. Disassemble and clean.
4. Repair or replace the valve.
5. Replace the parts.
Outside leakage
1. Diaphragm [11] is broken.
2. O ring [24] or Cover gasket [37] is
broken.
3. O ring [27] is broken.
1. Replace Diaphragm [11].
2. Replace the parts.
3. Replace O ring [27].
Abnormal noise
1. Nominal size is too large for these
specifications.
2. Air problem is caused. (Liquid use)
1. Replace with the correct nominal sized item.
(Refer to the “4. Nominal Size Selection
Method”.)
2. Install a trap.
* Foreign matter and scales in pipe may cause most of problems of pressure reducing valve. Be
careful sufficiently to foreign matter in pipe.
* Phenomenon alike valve trouble may happen by fault of pressure gauge, fluid leakage from by-
pass valve, forgetting to close the by-pass valve, clogging strainer, etc. First, check the said
before above troubleshooting.
