Maximum Working Pressure - Graco EM 490 Instructions-Parts List Manual

PRESSURE CONTROL CALIBRATION (See Fig 2 2 )
This procedure sets the sprayer to 2750 psi (190 bar) NEVER attempt to increase the fluid outlet pressure
MAXIMUM WORKING PRESSURE. by performing these calibrations in any other way.
This procedure must be performed .whenever a
NEVER EXCEED 2750 psi (190 bar) MAXIMUM
WORKING PRESSURE. Normal operation of the
ed and reinstalled or replaced to be sure the sprayer
microswitch, or pressure control assembly is remov- sprayer at higher pressures could result in compo-
nent rupture, fire or explosion.
is properly calibrated.
ALWAYS use a new 50 foot (15.2 ml spray hose
Improper calibration can cause the sprayer to over-
pressurize and result in component rupture, fire or
rated for 3000 psi 1210 bar) MAXIMUM WORKING
PRESSURE when performing this procedure. A
explosion. It may also prevent the sprayer from ob- used. underrated hose could develop a high pressure
taining the maximum working pressure which would
result in poor sprayer performance.
leak or rupture.
he pressure control
cover is removed to
Tools Needed: 4. Now check to see at what pressure the sprayer
NEW
50 ft
(15.2 m)
3000
psi (210 bar) airless spray starts to run again after stalling. Plug in the sprayer,
hose, Part No. 210541 turn it on, close the needle valve, and set the
Needle valve, Part No. 102-715 or 103-067
3/8'
open end wrench
pressure at maximum. Allow the sprayer to run until
it stalls.
Fluid-filled pressure gauge, Part No. 102-814
5 gallon p a i l end water 5. Now open the needle valve very slowly while ob-
Mineral spirits (for flushing after test) serving the pressure gauge. Check to see if the
pressure drops to approximately W K ) psi (161 bar)
1.
Follow the Preaaure Relief Procedure Wernlng
on page 14. Install the new
50
ft (15.2 m) spray
before starting again.
hose
to the sprayer outlet. On the other end of the
hose install the needle valve. Install the fluid-filled
I f the pressure is lower: shut off and unplug the
pressure gauge in the top port of the fluid filter. ferential wheel IF) counterdockwise just one notch
sprayer, but do not relieve pressure. Turn the dif-
and repeat Steps 4 and 5. Check the pressure drop
2. Open the needle valve slightly. Turn the pressure
control knob ID) to the minimum setting. Plug in
again, and repeat ii necessan/.
the sprayer and turn the switch ON. Increase the
pressure setting just enough to start the sprayer.
NOTE:
If you adjust the differential wheel, recheck
the stall pressure (steps 2 and 3 1 to be sure
Prime the hose, being
sure
to eliminate all air from
the system'.
the stall pressure has not changed.
3.
Open the needle vslve
a
little more-enough to
6.
Follow the Pressure Relief Procedure Warnlng
allow the pump to run continuously-and turn the
on page 14, flush the water out with mineral spirits,
relieve pressure again, then remove the test hose,
slowfy start to close the needle valve, but don't
pressure control knob to maximum. Now,
very
needle valve and pressure gauge.
the pump stalls, which should
be approximately
close
it
all the way. Observe the pressure a t which
2750 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
t o o
fast which gives a false
reading.
N
the pressures is lower: unplug the sprayer and
relieve pressure. Use a 3/8 open end wrench to
turn the pressure adjustment nut, at the bonom of
the pressure control knob shaft
(Rl,
counterdock-
wise 1 / 8 turn or less, then repeat steps 2 and 3.
If the pressure is higher: unplug the sprayer and
relieve pressure. Turn the pressure adjustment nut
dockwise 1/0 turn or 1 8 8 8 and repeat steps 2 and 3.
Repeat until the proper
stall
pressure is obtained.
22
307-735.
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