Precautions During Maintenance And Inspection - Yoshitake GP-2000 Installation & Operation Manual

Problem
2． Foreign matter exists between
3． Orifice of tee is clogged.
Reduced pressure
4． Reduced pressure is not adjusted
raises above than
the specified value.
5． Trap is not provided for dead-end
6． By-pass valve is leaking.
7． Pilot diaphragm [23] is damaged.
1． Nominal size is too large for the
2． Pressure reducing ratio is too large.
3． Drainage problem is caused.
Abnormal noise is
4． An abrupt OPEN/CLOSE valve is
heard.
5． Outlet pipe is too small.
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 particulars before above troubleshooting.
Consult factory when cannot make a judgement whether parts need replacement or not.

8.2 Precautions during 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)In order to maintain original performance and function, examine daily and personal
inspection. And, periodical inspection must be examined according to the regulations of
every kind.
※For general users, request to specialized dealer or manufacture.
(2)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.
(3)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.
(4)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.
(5)When adjusting pressure, slowly turn the adjusting screw.
※Incorrect adjustment may cause hunting, water hammer, etc., resulting in damage to
the valve and other equipment.
Cause
pilot valve and pilot valve seat, or
scratches exist.
correctly.
line.
specifications.
located too close to the pressure
reducing valve.
2． Disassemble
as-sembly, and clean or replace it.
3． Remove the orifice and clean it.
4． Observe the adjustment steps and
readjust pressure.
5． Install a trap.
6． Repair or replace it.
7． Replace the pilot diaphragm.
1． Change
appro-priately.
2． Reduce pressure in two stages.
3． Install a trap.
4． Allow as much as possible between
the valves.
5． Select a pipe size that will produce a
flow velocity of 30m/s or less.
-13-
Solution
the pilot valve
the nominal size
■EPDT-014f■