Dispense Valves - Graco PCF Instructions Manual

Troubleshooting

Dispense Valves

Problem
Valve not opening
Valve not shutting off
Sluggish open/close
Material leaks from back of valve
Air leaks from dispense valve
56
Cause
Air not getting to the open port
No "Valve On" signal from automa-
tion unit
Air not getting to the close port
(except AutoPlus valve)
"Valve On" signal from automation
unit is on
Air pressure low
Needle/seat worn
Pressurized material past the valve
shut-off is escaping
Shaft seal is worn
Loose air connections
Worn piston o-ring
Solution
Verify air pressure to solenoid
Check input from automation unit
Verify air pressure to solenoid
Verify solenoid operation
Verify air line routing and connec-
tions
Check input from automation unit
Verify air pressure is above 60 psi
(410 kPa, 4.1 bar)
Rebuild valve; replace needle/seat
Reduce running pressure
Reduce nozzle length
Increase nozzle orifice size
Rebuild valve; replace seals
Check air connections; tighten if
necessary
Rebuild valve; replace piston o-ring
3A2098A