Maximum Working Pressure - Graco EM 480 Hydra-Spray Instruction Manual

Pressure Control Calibration (See Fig 12)
USE EXTREME CAUTION WHEN PERFORMING THIS CALIBRATION PROCEDURE to reduce the risk of
an injection injury or other serious bodily injury which can result from component rupture, electric shock, fire, ex-
plosion, or moving parts.
This procedure sets the sprayer to 2750 psi (190 bar)

MAXIMUM WORKING PRESSURE.

This procedure must be performed whenever a new
or used circuit board, microswitch, or pressure con-
trol assembly is removed and reinstalled or replaced
to be sure the sprayer is properly calibrated.
Improper calibration can cause the sprayer to over-
pressurize and result in component rupture, fire or
explosion. It may also prevent the sprayer from ob-
taining the maximum working pressure which would
result in poor sprayer performance.
Tools Needed:
NEW 50 ft (15.2 m) 3000 psi (210 bar) airless spray
hose, Part No. 210541
Needle Valve, Part No. 102-715 or 103-067
Fluid-Filled Pressure Gauge, Part No. 102-814
5 gallon pail and water
Mineral Spirits (for flushing after test)
1 . Follow the Pressure Relief Procedure Warning on
page 12. Install a new 50 ft (15.2 m) spray hose to
the sprayer outlet, On the other end of the hose in-
stall a needle valve. Install a fluid-filled pressure
gauge in the top port of the fluid filter.
Open the needle valve
2.
control knob (D) to the minimum setting. Plug in
the sprayer and turn the switch ON. Increase the
pressure setting just enough to start the sprayer.
Prime the hose and pump with water, being sure to
eliminate all air from the system.
Open the needle valve a little more-enough to
3.
allow the pump to run continuously-and turn the
pressure control knob to maximum. Now, ve/y
start to close the needle valve, but don't
close it all the way. Observe the pressure at which
the pump stalls, which should be approximately
2756 psi (190 bar).
NOTE: The slower the pressure is brought up, the
easier it is to note the exact stall pressure.
Closing the needle valve quickly causes the
pressure to rise too fast which gives a false
reading.
is
the pressure lower:
relieve pressure. Use a 3/8" open end wrench to
turn the pressure adjustment nut, at the bottom of
the pressure control knob shaft (RI,
wise l/8 turn or less, then repeat steps 2 and 3.
relieve pressure. Turn the pressure adjustment nut
clockwise l/8 turn or less and repeat steps 2 and 3.
Repeat until the proper stall pressure is obtained.
WARNING
Turn the pressure
slightly.
unplug the sprayer and
counterclock-
unplug the sprayer and
NEVER attempt to increase the fluid outlet pressure
by performing these calibrations in any other way.
NEVER EXCEED 2756 psi (190 bar) MAXIMUM
WORKING PRESSURE. Normal operation of the
sprayer at higher pressures could result in compo-
nent rupture, fire or explosion.
ALWAYS use a 50 foot (15.2 m) spray hose
new
rated for 3000 psi (210 bar) MAXIMUM WORKING
PRESSURE when performing this procedure. A us-
ed, under-rated hose could develop a high pressure
leak or rupture.
AVOID touching the wire in the pressure control
assembly when the control box cover is removed to
reduce the risk of electric shock.
Fig 12
4. Now check to see at what pressure the sprayer
starts to run again after stalling. Plug in the sprayer,
turn it on, close the needle valve, and set the
pressure at maximum. Allow the sprayer to run until
it stalls.
5. Now open the needle valve very slowly while
observing the pressure gauge. Check to see if the
pressure drops to approximately 2356 psi (164 bar)
before starting again.
is
lower:
sprayer, but do not relieve pressure. Turn the dif-
ferential wheel (S)
counterclockwise
and repeat Steps 4 and 5. Check the pressure drop
again, and repeat if necessary.
NOTE:
If you adjust the differential wheel, recheck
the stall pressure (steps 2 and 3) to be sure
the stall pressure has not changed.
6. Follow the Pressure Relief Procedure, flush the
water out with mineral spirits, relieve pressure
again, then remove the test hose, needle valve and
pressure gauge.
ON/OFF SWITCH
shut off and unplug the
just one notch
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