Table 1-2.--Spray Gun Troubles, Possible Causes, and Remedies
TROUBLES
POSSIBLE CAUSES
REMEDIES
Air leaks from front of gun
Foreign matter on valve seat
Clean
Worn/damage valve seat
Replace
Sticking valve stem
Lubricate replace
Bent valve stem
Adjust
Loose packing nut
Fluid leaks from front of gun
Worn/damaged fluid tip/needle
Replace
Foreign matter in fluid tip
Clean
Packing nut too tight
Adjust
Wrong size needle
Replace
Jerky or fluttering spray
Insufficient material in container
Refill
(section and pressure feed)
Tipping container to excessive angle
Take greater care
Obstructed fluid passageway
Clean
Loose/cracked fluid tube
Tighten/replace
Loose fluid tip
Tighten/replace
Damaged tip seat
Tighten/replace
Jerky or fluttering spray
Material too heavy
Change to pressure feed
(suction feed only)
Clogged air vent in container lid
Clean
Loose/damaged coupling nut/cup lid
Tighten/replace
Fluid tube resting on bottom
Use proper fluid tube
Defective spray pattern
Air cap horn holes partially plugged
Rotate air cap 1/2 turn and spray
another pattern.
If defect is inverted, fault is on/in air
cap.
Dirt on air cap/fluid nozzle
If pattern is same, fault is on/in fluid
nozzle.
Clean proper part.
3,000 pounds psi. This pressure allows you to apply
Spray Head Removal.--Removal of the spray
paint to the surface as rapidly as you can move the gun.
head may be necessary for cleaning or repair. You may
need to change the head when the color of the paint is
Airless spray painting usually permits the use of
changed. With modern spray guns, this is a fairly
products with a higher viscosity. Less thinning is
simple operation. Refer to figure 1-24 and follow the
required, a better film is obtained, and the production is
procedures in table 1-3.
increased. A single hose leading to the gun makes it
easier to handle and causes less tiring to the painter.
AIRLESS SPRAY PAINTING.--Airless spray
The lack of overspray offers two other advantages:
painting uses hydraulic pressure. The equipment is
cleanup is easier and masking is minimized.
similar to conventional spray equipment except that
the pressure is generated by a hydraulic pump.
Because of the high pressure in an airless spray
Atomization of the paint is accomplished by forcing it
gun, you must ensure that your personnel receive
through a special-shaped orifice at a pressure up to
complete instructions on the proper use of airless spray
1-22
