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7. Operating Procedure
7.1 Warning and precaution on operation
Warning
( 1 ) Do not touch directly to pressure reducing valve with bare hands after flowing hot fluids
*Doing so may result in burns.
( 2 ) Before flow the hot fluids in the pipe line, make sure that the fluids will not cause the
risks through the end of piping system and the pipes are connected tightly.
*In case hot fluids blows out, it may result in burns.
Caution
( 1 ) When opening the by-pass stop valve, ensure that the reduced pressure will not exceed
set pressure of safety relief valve.
*In case reduced pressure exceeds set pressure of safety relief valve, the safety relief
valve operates and blows out the fluids.
( 2 ) When operation is discontinued for a long period of time, completely purge fluid from
pressure reducing valve and piping system, and close the stop valve located up stream
and down stream of pressure reducing valve.
*Water scales developed in the piping may cause erratic operation of pressure reducing
valve.
7.2 Adjustment Procedure
GD-24/24B pressure reducing valve is set at 0.1MPa at the factory. Change the set pressure as
appropriate.
Wrong or poor adjustment may cause hunting, scale buildup or water hammer, or severely
damage relevant parts. Be sure to follow the following steps to complete proper adjustment.
(Refer to the parts number in "3.2 Construction").
1) Close the stop valves at both sides of the pressure reducing valve, and thoroughly purge the
system through the by-pass line, with the by-pass valve opening adjusted so that the safety
relief valve is not activated. When completed, be sure to close the by-pass valve.
2) Slowly open the inlet stop valve, then open the outlet stop valve slightly, allowing a trickle
to be discharged.
3) Loosen the lock nut(12), and slowly turn the adjusting screw(11) (clockwise to increase,
counterclockwise to reduce) while observing the outlet side pressure gauge.
4) Slowly open the outlet stop valve to its full-open position.
5) After the adjustment, tighten the lock nut(12).
8. Maintenance Procedure
Be aware of foreign materials because many of faults on pressure reducing valve are due to the
existence of foreign materials. Please be reminded that our warranty does not cover damages
caused by foreign materials at the customer site. Failure resulting from faulty pressure gauge,
clogged strainer and leakage from by-pass stop valve are phenomena kindred to failure of pressure
reducing valve. Clogged strainer will decrease the secondary pressure and leakage from by-pass
pipe will increase the secondary pressure. Before do the troubleshooting of pressure reducing valve,
check such symptom of the strainer and stop valve.
-7-
■EPDT-209■
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