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CAUSES
OF
A RUNAWAY PUMP
speed, which can result in serious damage to the pump
Pump runaway refers to a rapid acceleration in pump
which can cause pump runaway are:
parts caused by overheating and scoring. Conditions
The fluid supply container is empty, or the fluid supply
has been interrupted.
The pump is cavitating, which means that it has lost
its
prime because an air pocket has formed around the
pump intake. This happens most frequently with high-
ly viscous fluids.
Afluid hose downstream from the pump has ruptured,
resulting in an increased pump cycle rate.
NOTE: The runaway valve may also trip if changes to
the system result in an increased cycle rate. For
example, if you increase the number of gun
drops, you should readjust the valve to account
for the increased cycle.rate.
When in a runaway condition, the pump requires much
valve senses this rapid increase in the volume of air be-
more air than during normal operation. The runaway
ing .used and greatly reduces the air flow, slowing the
pump to a crawl.
NOTE: The sudden surge of air when starting the
pump
may cause the valve to trip. Turn on the air slow-
ly, or readjust the valve.
ADJUSTING THE VALVE
1.
Loosen the adjustment locknut (24). See Fig 2.
2.
Check that the T-handle (2) is turned all the way
3.
Open the dispensing valve or trigger the spray gun.
4. Slowly open the main air shutoff valve (B), the air
regulator (F), and the bleed-type master air valve
(C). See Fig
1.
counterclockwise.
NOTE A faint hissing sound from the runaway valve is
from the poppet vent
(H)
during operation.
normal. The valve vents a small amount of air
5.
6.
Adjust the pump to the desired regulated air pres-
sure and cycle rate.
Turn the T-handle (2) clockwise until the runaway
valve trips. Press and hold the RESETvalve
(R);
you
will feel pressure on the RESET valve. Turn the han-
turns) until pressure on the RESET valve decreases.
die (2) counterclockwise (approximately 1 to
5
Release the RESET valve.
NOTE: At low pressure or a slow cycle rate, perform
til you feel a slight pressure pushing on the RE-
step
6,
then turn theT-handle (2) clockwise un-
counterclockwise distance in step 6.) This may
SET valve
(R).
(Turn it approximately half the
take several tries to achieve the proper setting.
7 . Tighten the locknut (24).
8.
Test the runaway valve as described in the following
paragraph.
TESTING THE VALVE
To test the runaway valve, press the TEST valve
0.
The
runaway valve should trip. Start the pump by pressing
the RESET valve (R) and holding it in for
5
seconds.
RESETTING THE VALVE
1.
Determine the condition that caused the runaway
valve to trip. Correct the condition.
2. If the air was shut off, turn it back on slowly. A sud-
den surge of air will cause the runaway valve to trip.
3. Press the RESET valve (R) and hold it in.for 5 se-
conds. The pump should restart.
NOTE: In some installations, particularly where there is
the air supply to reset the valve.
low air volume, it may be necessary to turn off
2
Fig 2
01263
4
308-201
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