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The valve is adjustable to control fluid pressures in a
circulating system from 0–180 psi (0–1.2 MPa, 0–12
bar).
The back pressure valve controls pressure ahead of its
intake.
Turn the adjusting screw (16) CLOCKWISE to in-
crease pressure, and COUNTERCLOCKWISE to
decrease pressure.
WARNING
Always open the valve and relieve the system
pressure before servicing.
Regular cleaning and inspection of the valve, based
upon the degree and kind of service, is essential.
Shut off the pump and relieve the line pressure by
turning the valve adjusting screw counterclockwise
until no spring tension is felt.
To clean and inspect the valve, remove it from the line,
disassemble, and clean with a compatible solvent.
CAUTION
Use special care in handling the valve to avoid
damaging the diaphragm (11) and the hard carbide
valve stem (15) and seat (19).
Operation
Adjust the pump pressure and back pressure valve for
best spraying combination and for proper circulation of
fluid.
Flush the valve with a compatible solvent whenever
the rest of the system or unit (pump, spray valve, etc.)
is being flushed. Open the valve before flushing (turn
the screw counterclockwise).
Service
Carefully inspect the diaphragm (11) for cracks or
other damage. Before reassembling, check for chips or
other dirt that could puncture the diaphragm. Check
also to see if the gasket (12) needs to be replaced.
Reinstall the diaphragm parts in reverse order. Torque
the retaining nut (9) to 12–15 ft-lb (16–20 NSm).
Carefully inspect the seat (19) for damage or wear.
Obstructing dirt could cause regulated pressure to
creep. Replace if necessary.
Replace the seat gasket (14) when replacing the seat
(19). Torque the seat to 15–20 ft-lb (21–27 NSm).
To remove or install the gauge (2), use a wrench on
the square portion of the gauge stud only. Use thread
sealer sparingly on the male threads of the gauge
when installing to prevent plugging the gauge.
Reassemble the remainder of the parts in reverse
order. Tighten valve capscrews (4) per sequence
shown on page 6. Check the torque after 24 hours,
and re-torque if necessary or if leaking occurs. Rein-
stall the back pressure valve in the line.
306770
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