Graco PR70 Operation & Maintenance Manual page 39

Problem
Material dispensed not correct weight Specific gravity of one or more of the
Machine dispensing off ratio
Pumps drawing material back from
valve hose
334116D
Cause
two materials has changed since cali-
bration
Machine air pressure has changed
since calibration
Not enough material in one or more
tanks
Mixer has slight obstruction
Check valve malfunction
Piston worn or broken
One tank is empty
Tank ball valve closed
Machine out of phase
Check valve malfunction
Piston worn or broken
Check valve stuck open
Troubleshooting
Solution
Recalibrate machine.
Readjust air pressure regulator to
value used when machine was cali-
brated, or recalibrate machine.
Check tank levels; fill and prime as
necessary.
Replace static mixer. Prime machine.
Remove check valve; clean or
replace as necessary.
Replace piston.
Check tank levels. Add material if
necessary.
Open tank ball valve. Prime machine.
Re-phase machine.
Remove check valve; clean or
replace as necessary.
Replace piston.
Remove check valve, clean or
replace as necessary.
39