Troubleshooting

Isolate a Mixing Problem

A mixing problem can be caused by a problem with the controller, meters, and solenoid valves, as well as the mix manifold.

1.To isolate the problem, check for any visible faults or errors:

a.Are all air and fluid tubes, hoses, and electrical cables properly connected?

b.Are valves and controls properly set?

c.Do the fluid supplies, solenoids, and spray gun have sufficient air pressure?

d.Do the fluid supplies need refilling?

2.If there is a process control problem, refer to your controller manual.

Common Causes

The flow rate is too high.

Highly unbalanced pressures from the fluid supply system.

Slow actuation of component A or B dispense valves.

System leaks.

Troubleshooting

Unbalanced Pressure

1.Check all component fluid supply pressures.

2.If the fluid supply pressures are not about equal, adjust their fluid pressure regulators, until the pres- sures are about the same.

3.If the pressures are already about equal, verify that the dose valves are operating properly.

Dose Valve Operation

Manually operate the dose valves by actuating their solenoids. The valves should snap open and shut quickly. If the valves move slowly, it could be caused by:

Air pressure to the valve actuators is too low. Minimum: 75 psi (0.52 MPa, 5.2 bar) Recommended: 85 psi (0.6 MPa, 6.0 bar).

Valve actuating air constricted by dirt or water in the air supply.

Solenoid or tubing restricted.

Dose valve seals need lubrication (see manual 312782).

Air piston o-rings and packings are not lubricated (see manual 312782),

Valve setting is turned out too far. See Mix Manifold Valve Settings, page 8.

312781E

9

Page 9
Image 9
Graco 312781E Troubleshooting, Isolate a Mixing Problem, Common Causes, Unbalanced Pressure, Dose Valve Operation