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2.
Fully open the stop valve at the inlet side slowly, and open the stop valve at the outlet side so that a
little fluid can flow through.
3.
Remove the domed cap nut [17] (loosen the nut [41] in the case of nominal size 125A and 150A),
and turn the adjusting screw [14] while watching the pressure gauge at the outlet side.
• Turn the adjusting screw to the right (clockwise) to increase the reduced pressure.
• Turn the adjusting screw to the left (counterclockwise) to decrease the reduced pressure.
4.
Fully open the stop valve at the outlet side slowly.
5.
After the adjustment is complete, tighten the domed cap nut [17] (nut [41] in the case of the nominal
size 125A and 150A).
7.1 Troubleshooting
Trouble
Abnormal pressure
rise at the outlet side.
Reduced pressure
does not reach the
desired value.
Outside leakage
Abnormal sound
Most of problems with the pressure reducing valve are caused by foreign substances and scale in the
piping. Avoid the ingress of dust and dirt to the product with caution.
A phenomenon similar to valve failure could occur due to the failure of the pressure gauge, leakage or
insufficient tightening of the globe valve in the by-pass line, clogging of the strainer, and other causes.
Check the above possible causes and take a proper remedy and preventive measures.
8. Maintenance
Cause
1. Foreign substances stuck between
the disc [8] and the valve seat [3],
or scratch on them.
2. The O-ring [6] is damaged.
3. The diaphragm [9] is damaged.
4. There is a leakage from the globe
valve of the by-pass line.
1. The working pressure is improper.
2. The nominal size of the product is
too small for the flow rate for use.
3. Pressure adjustment is improper.
4. Strainer [10] built in the product is
clogged.
5. The strainer installed at the inlet
side of the product is clogged.
1. Bolt [18] or [39] is loosened.
2. O-ring [30] is damaged.
3. Strainer cap [11] or plug [31] is
loosened.
1. The nominal size of the product is
too large for the specifications of
the system.
2. The pressure reduction ratio is too
large or the maximum pressure
difference is exceeded.
3. Air binding has occurred.
4. A quick operating valve is located
near the product.
1. Disassemble the product and remove
the foreign substances. If scratch is
observed on the valve disc or valve
seat, replace it.
2. Replace the O-ring.
3. Replace the diaphragm.
4. Repair or replace the globe valve.
1. Correct the working pressure. (See
"2.1 Specifications" on Page 1.)
2. Replace the product with the proper
nominal size. (See "2.2 Nominal size
selection" on Page 3.)
3. Readjust the pressure in accordance
with the given procedure. (See "6.2
Adjusting procedure" on Page 12.)
4. Clean the strainer. (See "7.5 Strainer
cleaning procedure" on Page 16.)
5. Clean the strainer.
1. Tighten the bolts.
2. Replace the O-ring.
3. Tighten the strainer cap or plug.
1. Replace the product with the proper
nominal size. (See "2.2 Nominal size
selection" on Page 3.)
2. Reduce pressure in two stages. (See
"2.1 Specifications" on Page 3)
3. Install an air vent device.
4. Keep a distance between them as
large as possible. (3 m at least)
13
Remedy
PDT-008o
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