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System Verification
Graco recommends running the following tests daily.
Check for Normal Operation
Every time you start spraying:
•
Watch the fluid pressure gauges (FF). A pressure
drop occurs during pump stroke changeover. It
should be quick and synchronous.
•
Stop the pumps on the upstroke. Check that both
gauges hold pressure for at least 20 seconds. See
Pump Troubleshooting on page 47.
If one gauge drops, the others will rise.
•
Stop the pumps on the down-stroke. Check that all
gauges hold pressure.
•
If using feed pumps, check that both feed pumps
run during the proportioner upstroke.
Mix and Integration Tests
Use the following tests to check for proper mix and
integration.
Butterfly Test
At low pressure, and with the spray tip reversed,
dispense a 1/2 in. (12.7 mm) bead of material onto foil
until multiple changeovers of each pump have occurred.
Fold the sheet of foil over the fluid then peel it back and
look for unmixed material (appears marble-like), or color
changes.
Curing Test
Spray a single continuous pattern on foil at typical
pressure setting, flow rate, and tip size until multiple
changeovers of each pump have occurred. Trigger and
de-trigger at typical intervals for the application. Do not
overlap or cross over your spray pattern.
Check curing at various time intervals, listed on the
material data sheet. For example, check for dry to touch
by running your finger along the test pattern's entire
length at the time listed on the data sheet.
3A0420ZAF
Spots that take longer to cure indicate insufficient pump
loading, leakage, or lead/lag errors at a remote mix
manifold.
Appearance Test
Spray material onto foil. Look for variations in color,
gloss, or texture that may indicate improperly catalyzed
material.
Monitor Fluid Supply
NOTE: To prevent pumping air into the system, which
causes incorrect proportioning, never allow the feed
pump or solvent pump containers to run dry.
An empty pump will quickly accelerate to a high speed,
and may damage itself and the other displacement
pump because it causes a pressure rise in the other
pump. If a supply container runs dry, stop the pump
immediately, refill the container, and prime the system.
Be sure to eliminate all air from the system.
Check Pot Life
Check the fluid manufacturer's instructions for fluid pot
life at your fluid temperature. Flush mixed fluid out of the
mix manifold, hose, and gun before pot life time expires,
or before a rise in viscosity affects the spray pattern.
Ratio Check
Check the ratio at the mix manifold after any changes to
the proportioning system. Use Ratio Check Kit 24F375
to check the ratio at the mix manifold. See your ratio
check kit manual for instructions and parts.
To prevent an inaccurate ratio check when feed pumps
are used in your system, the feed pressure cannot be
more than a maximum of 25% of the proportioner outlet
pressure. High feed pressure can float the proportioner
pump check balls, resulting in an inaccurate ratio check.
There must be back pressure on both sides of the mix
manifold when checking the ratio.
Operation
43
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