SB-2-001-F Page 5
Figure 10 Horizontal Test Pattern with Even Mate-
rial Distribution
If the pattern produced by the above test appears
normal, rotate the air cap back to a normal spraying
position and begin spraying (Example - a normal
pattern with a #9000 air cap will be about 9" long
when the gun is held 8" from the surface.) With the
fluid adjusting screw open to the first thread and
the air pressure set at approximately 30 psi, make
a few test passes with the gun on some clean paper.
Move the gun faster than usual when spraying the
test passes. If there are variations in particle size -
specks and/or large globs, the paint is not atomiz-
ing properly (See Figure 12). If the paint is not
atomizing properly, increase the air pressure slightly
and make another test pass. Continue this se-
quence until the paint particle size is uniform.
If the pattern seems starved for material and the
fluid adjusting screw is open wide (to the first
thread), the atomization air pressure may be too
high, or the material may be too heavy. Recheck the
viscosity or reduce the air pressure.
If the material is spraying too heavily and sagging,
reduce the material flow by turning in the fluid
adjusting screw (clockwise).
Figure 11 Pattern with Uneven Particle Size
Pressure Feed Components
A pressure feed system consists of a pressure feed
spray gun, pressure feed tank, cup or pump, an air
filter/regulator, appropriate air and fluid hoses and
an air compressor.
Connect the air hose from the air regulator to the air
inlet on the gun. Connect the mainline air hose to
the air inlet on the tank, cup or pump.
To avoid hazardous bursting or equipment
damage, do not exceed the container's maxi-
mum working pressure.
Connect the fluid hose from the fluid outlet on the
tank or pump to the fluid inlet on the gun.
Open spreader adjustment valve for maximum pat-
tern size. Open fluid adjustment screw until the first
thread is visible.
Shut off atomization air to the gun. Set the fluid
flow rate by adjusting the air pressure in the mate-
rial container. Use about 6 psi for a remote cup and
about 15 psi for a 2-gallon, or larger, container.
Adjust the fluid flow in the following ways:
Remove the air cap. With atomization air off, pull
the trigger, flowing material into a clean, graduated
container for 10 seconds. Measure the amount of
material which flowed in that time and multiply
times 6 (or flow for 30 seconds and multiply time 2).
This is the fluid flow rate in ounces per minute. For
standard finishing, it should be about 14 to 16
ounces per minute. If the flow rate is less than this,
increase the air pressure in the container and re-
peat.
When the flow rate is correct, reinstall the air cap.
If fluid pressure at the tank, cup or pump exceeds 20
psi, the next larger fluid tip size should be used.
Turn the atomizaton air to about 30 psi at the gun.
Spray a fast test pattern on a clean sheet of paper
and check the consistency of the particle size.
Increase or decrease the air pressure until even
particle size is achieved.
Spray a horizontal test pattern holding the trigger
open until the material begins to run. Paint distribu-
tion across the full width of the pattern should be the
same (adjust with fan pattern adjustment). If it
cannot be adjusted, there may be a problem with
either the air cap or the fluid tip which must be
corrected. Refer to the Troubleshooting Section.
Hints for good spray technique.
Hold gun perpendicular 6" to 8" (HVLP guns) or 8"-
10" (suction, gravity or pressure conventional feed
guns) to surface being sprayed.
Don't tilt the gun in any direction. This will result in
uneven paint build causing runs and sags.
Trigger gun just before the edge of the surface to be
sprayed. The trigger should be held fully depressed
and the gun moved in one continuous motion, until
the other edge of the object is reached. Release the
trigger but continue the motion for a few inches until
it is reversed for the return stroke.
If distribution is not even, there is a problem with
either the air cap or the fluid tip. Refer to the
TROUBLESHOOTING section for examples of faulty
patterns to help diagnose the problem.
