Graco 25R490, Instructions - Parts Manual

Page: 7 / 16

Operation
3A7681A 7
Operation
Pressure Relief Procedure
Follow the Pressure Relief Procedure whenever
you see this symbol.
1. Engage trigger lock.
2. Follow the recommended shut down procedure from
the respective pump manual.
3. Close the Bleed Type Shut Off Valve (J) on the Air
Regulator (H) to the pneumatic BPR to reduce fluid
pressure to zero. Turn the adjusting screw on the
mechanical BPR counterclockwise to reduce the
fluid pressure to zero.
4. Disengage trigger lock.
5. Hold a metal part of the gun firmly to the side of a
grounded metal pail, and trigger the gun to relieve
pressure.
6. Engage trigger lock.
7. Open the Drain Valve (L) (required in your system).
Have a container ready to catch the drainage.
8. Leave the drain valve open until you are ready to
spray again.
9. If you suspect the spray tip or hose is clogged or
that pressure has not been fully relieved:
a. VERY SLOWLY loosen the tip guard retaining
nut or the hose end coupling to relieve pressure
gradually.
b. Loosen the nut or the coupling completely.
c. Clear the obstruction in the hose or tip.
Adjusting the BPR
The BPR controls pressure upstream from the BPR.
Adjust the pump fluid pressure and the BPR for the best
spraying combination and proper circulation of the fluid.
• The pneumatic pilot operated BPR fluid pressure is
adjusted by increasing or decreasing the pilot air
pressure. The fluid to air pressure ratio ranges from
10:1 to 30:1 depending on the model chosen for the
application. See Technical Specifications, page
14.
• The mechanical operated BPR fluid pressure is
adjusted by rotating the adjusting screw clockwise
to increase fluid pressure and counterclockwise to
decrease fluid pressure.
This equipment stays pressurized until pressure is
manually relieved. To help prevent serious injury from
pressurized fluid, such as skin injection, splashing
fluid and moving parts, follow the Pressure Relief
Procedure when you stop spraying and before
cleaning, checking, or servicing the equipment.