April 27, 2007

Common Mechanical Purge Gun Problems:

1. Material leaks when trigger not pulled:

-Coupling block seals leaking. They are either scratched or damaged.

-Leaking material around front of gun. The pattern control disc retainer is not tight.

2. Low volume of material:

-Restricted mixing module.

-Low spray pressure.

3. Gun blows air while trigger is pulled. Air escapes around bottom of gun:

-”O” rings in trigger valve shaft are worn or broken.

4. Low spray pressure:

-Restricted air flow.

-Solids are on isocyanate(ISO)pump rod or in wet cup.

- Regulator is not adjusted properly and/or is not operating correctly.

5. Trigger sticks:

-Build up of solids on valving rod.

6. Material steams the dose but does not atomize:

-Low heat; check thermometers and hose temperature setting. Is the hose up to the correct temperature?

-Low spray pressure.

7. Spotting small amount of uncured material on surface of product:

-Worn module.

-Adjust the forward stop.

8. Air leaks from gun valve assembly:

-Worn or broken “O” rings.

9. Cross over:

-Polymerized material in the check valves.

-Cross over is caused by material from one side pushing its way across the mixing module into the other side.

-Never start spraying with large difference in pressure such as one side at a low pressure and the other

at a high pressure.

-Always equalize pressure before spraying.

-A back up into the check valve assembly is a sure sign of a worn check valve. Replace check valve assembly.