Advertisement
As the valve opens it freely draws oil from the
reservoir into the piston chamber.
As the pressure subsides the spring force will push
the valve closed, forcing oil back into the reservoir
through a needle valve that controls the speed at
which the valve closes.
VALVE CONSTRUCTION
The standard Figure 625-D surge relief valve has a
cast iron body and cover, stainless steel body seat,
stainless steel disc stem, resilient disc seat and alloy
steel compression springs housed in a fabricated
steel spring chambers.
The valve incorporates a self-contained hydraulic
dashpot to control the speed at which the valve closes
during pressure subsidence.
Refer to the List of Materials submitted for the order if
non-standard materials were provided.
Refer to Page 5 for details of construction and parts
location.
START-UP
The valve generally does not require any calibration
or adjustment prior to start-up. The pressure at which
the valve opens is set at the factory per the
Engineer's specification and indicated on a tag wired
to the valve. This pressure is typically 10 to 15%
higher than the highest pressure that would be
present at the valve's inlet.
The valve is shipped from the factory with the oil
reservoir full of oil and a pipe plug in the fill port to
prevent spillage during transit and installation.
IMPORTANT: Prior to start-up remove the pipe plug,
check to make sure reservoir is ¾" full and replace
with the blue plastic vented plug that is wired to the
reservoir.
If additional oil is needed, use AW32 Hydraulic Fluid.
The closing speed needle valve (23) should be initially
opened ¼ turn.
Since the relief valve's opening pressure is always
higher than the "normal" pressure, an abnormally high
pressure is needed to test the valve's operation.
This may be accomplished by throttling valve but
most of the time the pumping system is started then
shut down and the reaction of the relief valve is noted.
If necessary, the pressure at which the valve starts to
open can be field adjusted by simultaneously turning
both adjusting nuts equally.
counterclockwise to lower the opening pressure. Turn
both nuts clockwise to raise the opening pressure but
do not exceed the maximum set pressure for the
installed springs. If a higher opening pressure than
Turn both nuts
2
the springs allow is required, consult the factory for
replacement springs.
Small adjustments to the closing speed may be made
if needed. Loosen lock nut on closing speed control
valve and turn screw clockwise to slow closing speed,
counterclockwise to increase closing speed.
CAUTION: Do not completely close the needle valve
as this will prevent the relief valve from closing once it
has opened.
PREVENTIVE MAINTENANCE
Figure 625-D sewage surge relief valves require no
routine
lubrication,
adjustment,
maintenance.
A monthly inspection should be performed for the first
6 months of operation to ensure there is no external
fluid leakage or audible evidence of water leaking
through the closed valve.
Thereafter, a quarterly visual inspection should be
performed.
TROUBLESHOOTING
•
Valve Fails to Open at Desired Pressure
- Set pressure too high – adjust springs
- Inlet isolating valve closed – open valve
•
Valve Fails to Close
- Set pressure too low – adjust springs
- Closing speed valve closed – adjust ¼ turn
open
- Closing speed hydraulic tubing kinked or
clogged – repair/replace/clean tubing
•
Leakage Through Valve When Closed
- Debris lodged under seat – inspect/clear
- Damaged disc seat – inspect/replace
•
Valve Closes Erratically
- Low or no oil in reservoir – fill ¾ full
- Air in hydraulic line/dashpot chamber- bleed
air
•
Leakage from Weep Hole in Cover
- Worn stem seals (19) - Replace
WARNING
Removing the valve from the line or disassembling
the valve while there is pressure in the valve body
may result in injury or damage to the valve
WARNING
Follow all applicable safety regulations and codes and
read and understand all instructions before
undertaking disassembly.
DISASSEMBLY
Figure 625-D surge relief valves can be serviced
while the body remains connected to the pipeline. A
skilled technician should perform all work. No special
tools are required but due to the weight of large size
valve's components overhead lifting capability is
beneficial.
or
preventive
Advertisement
