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3.
Remove the domed cap nut [17] and turn the adjusting screw [14] while watching the pressure gauge
on 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.
*If the pressure is not set under the condition that the stop valve on the outlet side is
slightly opened, closing the stop valve on the outlet side while operation may lead to shut-off
pressure rise exceeding the set pressure.
4.
Fully open the stop valve on the outlet side slowly.
5.
After the adjustment is complete, tighten the domed cap nut [17]
6.1 Troubleshooting
Trouble
Reduced pressure
exceeds the
set pressure.
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 measure.
6. Maintenance
Cause
1. Foreign
substances
between disc [8] and valve seat [3],
or either of the parts is damaged.
2. The O-ring [6] is damaged.
3. The diaphragm [9] is damaged.
4. By-pass globe valve leaks.
1. Working pressure is improper.
2. Nominal size of the product is too
small for the specifications of the
system.
3. Pressure adjustment is improper.
4. Strainer [10] built in the product is
clogged.
5. The strainer installed on the inlet
side of the product is clogged.
1. Bolt [18] or [39] got loose.
2. O-ring [30] is damaged.
3. Strainer cap [11] or plug [31] got
loose.
1. 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-induced trouble.
4. An on-off valve is installed near the
product.
5. The pipe diameter is narrowed within
3m before and after the pressure
reducing valve.
are
stuck
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 by-pass globe
valve.
1. Correct the working pressure. (See
"1.1 Specifications".)
2. Replace the product with one of
proper
Nominal size selection")
3. Readjust the pressure in accordance
with the given procedure. (See "5.2
Adjusting procedure")
4. Disassemble and clean it. (See "6.5
Strainer cleaning procedure")
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 one of
proper nominal size.
2. Reduce pressure in two stages. (See
"1.1 Specifications")
3. Install an air vent.
4. Take as large distance as possible
from the on-off valve.
5. Make sure that pipes at least 3m
before and after the pressure reducing
valve are of the same diameter.
10
Remedy
nominal
size.
(See
EPDT-351
"1.2
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