OPERATING INSTRUCTIONS
MODEL BPS-09i FLG
BACKPRESSURE/BYPASS VALVE
DISASSEMBLY/ASSEMBLY INSTRUCTIONS:
If uid is leaking from the adjusng screw, the diaphragm is sus-
pect. Inspect the diaphragm (9), replace if torn, abraded, or de-
laminated or otherwise damaged or cut. Sealing area of the
diaphragm should be free from tears or cuts, otherwise external
leakage will occur. Examine to see if there are signs the dia-
phragm pulled away from the outer clamped seang area. If so,
realign diaphragm and make sure the spring chamber is ght-
ened properly, and checked again for ghtening aer full tem-
perature is reached aer installaon. Also, check to make sure
the locknut (6) is ght which holds the diaphragm metal plates
together (8) & (10). A spare diaphragm should always be kept
on hand to keep down me to a minimum.
Examine the main valve (12) and seat area for excessive wear
parcularly in the valve seat area. If excessive, replace with
new parts. Otherwise, parts may be restored by remachining
and re-lapping with a ne lapping compound, such as 600 or
800 grit. Replace external valve spring (5) if corroded or dam-
aged.
Reassemble valve in the same sequence as disassembled mak-
ing sure the diaphragm lock nut (6) and spring chamber (3) are
ght so that no leakage can take place in these areas. Apply
approximately 45 -lbs of torque to ghten the diaphragm lock
nut (6) and approximately 500 -lbs to the spring chamber (3).
Also examine the O-ring seal for the boom plug to make sure it
is not damaged or shows signs of deterioraon. Replace if nec-
essary. It is oen easier to assemble the spring chamber assem-
bly upside down by dropping the spring and spring hardware
into the spring chamber. Then the body (13) subassembly with
the main valve (12) and diaphragm (9) can be posioned over
the spring chamber (3) and threading the assembly together
unl hand ght. Then the nal ghtening with a wrench can be
done with the valve right side up.
Aer the valve is properly assembled, reset the spring adjusng
screw (1) unl the desired outlet pressure is achieved at the
ow range the valve will be operang. Then ghten the ad-
jusng screw lock nut (2). Note that some valves, may require
readjustment of the spring seng if there are wide ranges in
ows. Consult factory for applicaon assistance if a dierent
spring or if a dierent valve is required.
PRINCIPLE OF OPERATION:
This is a direct-acng valve with an adjustable spring operang
against a exible elastomeric diaphragm subjected to the inlet pres-
sure of the valve. Increasing the spring compression will increase the
system or line pressure to be maintained. Reducing the spring com-
pression will reduce the system or line pressure to be maintained. An
increase in system pressure beyond the set point will cause the main
valve to open and relieve the excess pressure.
OPERATING INSTRUCTIONS
If the valve has not been ordered preset to a specic set pressure,
simply adjust the spring (5) compression by loosening the lock nut (2)
and turn the adjusng screw (1) clockwise to increase the spring
compression. This will increase the set pressure. Similarly, turning
the screw counterclockwise will reduce the spring compression and
correspondingly reduce the setpressure.
Phone: 973-340-9955 Fax: 973-340-9933
http://www.straval.com Email: sales@straval.com
If the regulator fails to maintain the proper pressure, there
could be a number of probable causes as follows: Internal clog-
ging of foreign objects or material, sediment, rust, etc. in the
valve seat area, sensing port, diaphragm cavity and valve spring
cavity which houses the spring.
this condion appears frequently a strainer installed at the inlet
side of the valve is recommended. If disassembly is required,
make sure the valve piping is not under pressure and suciently
cooled o for operang personnel to handle. To disassemble
the valve, it is not necessary to remove the valve from the pip-
ing, although it may be more convenient to work on the valve at
a bench with a vise. Unscrew the spring chamber (3) with a
wrench.
