Troubleshooting Guide to Air Atomizing Spray Guns

Posted in Firwood Hints and Tips by Firwood Paints on August 30th 2019
At times your Air Atomizing Spray Gun may have a problem that you have been unable to solve. Here we will offer some common problems, the possible causes, and what the solutions are for each issue.

Problem: Fluid leaking from packing nut
Cause & Solution: The cause can be down to either the packing nut being loose or the packing becoming worn or dry. To resolve the former simply tighten the nut, being careful not to bind the needle. For the latter you can try lubricating first, or else replace.

Problem: Air leaking from front of spray gun
Cause & Solution: The air valve stem may be sticking or foreign matter may have built up on the air valve or seat. Try cleaning and lubricating in these instances. Alternatively, the air valve or seat may have become damaged or worn. This will require replacing. Other causes include damage to the air valve, valve stem, or valve spring. The solution to these issues is to replace the damaged or worn part.

Problem: Fluid dripping or leaking from the front of the pressure feed gun
Cause & Solution: Causes for this may include dry packing. In which case, lubrication is required. Alternatively the packing nut may be too tight, which will require an adjustment. The fluid tip or needle may have become worn or damaged and may need replacing. Also consider checking for foreign matter in the tip and cleaning where possible. Other causes, which will require part replacements, include a broken fluid needle spring or a wrong sized needle or tip.

Problem: Spray has started fluttering
Cause & Solution: Depending on your system the problems and solutions may vary. If your system is a Suction Feed it may be that the material is too heavy, requiring thinning or reduction. The air vent may have become clogged, which will require cleaning. The lid may be loose, dirty, or damaged. This will need checking and either cleaning, replacing or tightening via the coupling nut. Alternatively, the fluid tube may be resting on the cup bottom and this will need either tightening or shortening. Another suction feed related issue may be that the gasket behind the fluid tip has become damaged. This will need replacing.

Across all feed systems there are other causes to consider. The fluid tip or seat may have become loose or damaged. This would need either tightening or replacing. Any dry packing or loose fluid needle packing nuts will need lubricating or tightening. It may be that the material level has become too low and requires refilling. The container may be tipped too far during use and this will require you holding the spray gun more upright whilst in use. The fluid passage may have become obstructed and will require back-flushing with solvent or it could be that the fluid tube or flued inlet nipple have become loose or broken, which will require tightening or replacing.

Problem: Top or bottom heavy spray pattern
Cause & Solution: Horn holes may be plugged, there may be an obstruction on the top or bottom of the fluid tip or the cap and/or tip seat may be dirty. To remedy this issue you will need to clean the relevant parts of the air atomizing spray gun.

Problem: Right or left heavy spray pattern
Cause & Solution: Horn holes may be plugged, there may be dirt on the left or right side of the fluid tip. To remedy this issue you will need to clean the relevant parts of the air atomizing spray gun.

Problem: Centre heavy spray pattern
Cause & Solution: There are several potential causes to this problem. The fluid pressure may be too high for pressure feed, which will require you to balance air and fluid pressure and increase spray pattern width. It may be that material flow exceeds the air caps capacity which will need you to thin or reduce fluid flow. The spreader adjustment valve may be set too low and require adjusting. The atomizing pressure may be too low and require an increase, or the material may be too thick and require thinning or diluting to the proper consistency.

Problem: Split spray pattern
Cause & Solution: The causes of split spray patterns vary. It may be that the fluid adjusting knob is turned in too far and will need turning counter-clockwise to increase flow. It may be that atomization air pressure is too high and will require a reduction at the regulator. Fluid pressure may be too low and require an increase or the fluid tip may be too small, in which case you will need to change to a larger tip.

Problem: Starved spray pattern
Cause & Solution: In this case the material flow may be inadequate and require backing out the fluid adjusting screw to the first thread or increasing the fluid pressure. Alternatively it may be that there is a low atomization air pressure on suction feed systems. This will require an increase in air pressure and the rebalancing of the gun to resolve.

Problem: Unable to form round spray pattern
Cause & Solution: It is likely in this instance that the fan adjustment stem is not properly seating and will need cleaning or replacing.

Problem: Dry spray
Cause & Solution: Causes of this could be the air pressure being too high and require lowering. It may also be that the material has not been properly reduced and need thinning or diluting. Firwood Paints offer a range of Paint Thinners for the thinning of paints and the cleaning of related application equipment. The gun could be too far from the surface or be moving too fast.

Problem: Excessive overspray
Cause & Solution: There are several causes to excessive overspray from an air atomizing spray gun. It may be that there is too much atomization air pressure, requiring a reduction. Alternatively it could be that the gun technique being used is improper, such as arching, or the gun being moved too fast. The gun could be too far from the surface.

Problem: Excessive fog
Cause & Solution: Excessive fog may be caused by too much solvent, or a too-fast-dying solvent. This will require remixing with the correct temperature solvent. Alternatively there may be too much atomization air pressure and require reducing.

Problem: Will not spray
Cause & Solution: A pressure feed cap or tip may be being used with a suction feed. In this case you will need to change the cap or tip to one suitable for a suction feed. There may be no pressure at the gun, needing the air lines to be checked. If the fluid needle is not retracting you will need to open the fluid adjusting screw. Alternatively the fluid may be too heavy on a suction feed system, which will require a lower fluid viscosity or a change to the pressure feed.

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