Graco MD2 [12/30] Troubleshooting

Troubleshooting

12 312185T

Troubleshooting

Problem Cause Solution

Valve does not open. Insufficient air pressure. Tur n on air or increase air pressure.

Air not exhausted from the front side

of air cylinder piston.

Use 4-way, relieving type air valve.

Valve does not close and leaks. Insufficient air pressure. Turn on air or increase air pressure.

Air not exhausted from the back side

of air cylinder piston.

Use 4-way, relieving type air valve.

Blockage between needle and seat. Remove and clean needle and seat.

Damaged or missing gasket between

seat and housing (hard seat only).

Replace gasket (38).

Damaged or worn needle or seat. Replace both the needle and seat.

Too little snuff-back. Unscrew snuff-back adjustment nee-

dle (25) 1/4 turn at a time.

Higher than nor mal back pressure. Nose piece is clogged. Remove and clean.

Mixer is curing. Replace mixer.

Soft spots in mixed material. Nose piece is clogged on one side. Remove and clean.

System is not properly balanced. Balance system with hoses, check

valves, restrictors.

High static pressures build when

valve shuts off.

Tur n off proportioner pump when

valve closes.

Low flow rate. Snuff-back rings (13) are installed

(hard seat only).

Remove snuff-back rings if they are

not required for maximum snuff-back.