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● Foreign matter and scales in a pipe may cause most of problems of pressure reducing
valve. Be careful sufficiently to foreign matter in a 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, and etc.
First, check the said before above troubleshooting.
● Consult factory when cannot make a judgement whether parts need replacement or not.
7.2 Precautions for maintenance and inspection
Warning
(1) Completely discharge internal pressure from the valves, lines, and equipment, and cool
the valve down to a level where you can touch it with bare hands before disassembly and
inspection.
* Failure to do so may result in injury or burns due to residual pressure or spillage around
the valve.
Caution
(1) Pressure reducing valve shall be disassembled and inspected by qualified person or
manufacture.
* Request the treatment to specialized dealer or manufacture in case of any problems.
(2) While disassembly, drain flow out from the valve, so catch it by container. And release steam
completely before disassembling.
* In case of no container for drain, it makes dirty surrounding the valve.
(3) Close the stop valves before and after the pressure reducing valve, and remove all foreign
matter and scales via the by-pass line before operation.
* Failure to do so may prevent the valve from functioning correctly.
(4) Remove condensate completely from the line, and close the stop valves before and after the
valve when not using it for long periods of times.
* Rust generated in the valves and lines may cause malfunction.
(5) In case of no operation for a long period of time, perform operating exam before start operation
again.
* Request the treatment to specialized dealer or manufacture in case of any problems.
7.3 Disassembly
Be sure that the stop valves at inlet and outlet side of pressure reducing valve is closed and
all internal pressure and condensate have discharged before disassembling the valve.
(1) Pilot valve
1. Set the operating air pressure to no pressure.
2. Remove bolt [60] of cover [57].
3. For GPK-2001, remove the pilot diaphragm [23], the diaphragm case [58], and pilot
diaphragm plate [59].
3. Remove pilot valve assembly using a ring spanner or socket wrench (nominal size 22).
(2) Main valve
1. Remove pipe A [34] at joint A [30] or tee [33].
2. For nominal sizes 15A to 40A, remove bolt [38] of pilot body [2]. Dismount the pilot body
from the body [1]. And remove spring plate [14], screen [15], main valve spring [13], and
main valve [6]. For nominal sizes 50A to 100A, remove bolt [44] of spacer [54] and
remove the spacer from the main body [1], main valve spring [13], and entire main valve
([6], [9], [50], and [51]) (for nominal size 50A, main valve spring, and main valve [6])
-16-
■EPDT-098a■
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