DeVilbiss FAC752-3 User Manual download pdf (Page 5)

SB-2-001-H Page 5

Figure 10 Horizontal Test Pattern with Even Ma-

terial 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

atomizing properly (See Figure 11). If the paint is

not atomizing properly, increase the air pressure

slightly and make another test pass. Continue this

sequence 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

pattern 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 ma-

terial 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 repeat.

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 distri-

bution 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 (See

Figure 12 on next page).

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.

adjustment. 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.

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DeVilbiss FAC752-3 User Manual Page 5

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