15
■EPDT-179c■
8.4 Troubleshooting procedure
Disassembling warning
WARNING
Before beginning disassembling or inspection, completely release all pressure from the
pressure reducing valve, piping and equipment. If the fluid used is hot, wait until the valve
cools down. Never touch valve with bare hands while they are still warm.
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Residual pressure in the pressure reducing valve, piping or equipment may cause injury or
burning; or may contaminate work area.
Reassembling precautions
CAUTION
(1)
Visually inspect the disc and valve seat for no development of flaw, dirt and dent.
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Otherwise, the reduced pressure will increase: clean the dirty surface and replace
damaged parts.
(2)
Verify smooth up/down movement of the valve stem.
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Jerky movement will cause malfuction.
(3)
Verify that the seat, diaphragm, balance diaphragm and O-ring are clean.
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Dirty components will cause malfunction and leakage.
(4)
Apply silicone grease to the O-ring and balance diaphragm to be assembled.
(Recommended silicone grease: G501, Shin-Etsu Chemical Co., Ltd.)
Problem I : Reduced pressure exceeds prescribed value.
Presumable cause I.1: Leakage from stop valve connected on bypass pipe.
Action (1) : Close the stop valve connected to the bypass pipe.
Action (2) : If problem persists, replace the stop valve.
Presumable cause I.2: External sensing pipe is not connected.
Action (3) : Connect the external sensing pipe. (See 6.1, Fig.2 Diagram of piping example.)
Presumable cause I.3: Needle valve
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37
is clogged by foreign materials.
Action (4) : Using a flat head screwdriver, remove the needle valve.
