Setting The Atomization Fluid Pressure - Graco PRO AA5500SC Instruction Manual

Setting the Atomization Fluid Pressure

NOTE: Atomization fluid pressure will vary based on
the viscosity of the fluid, the flow rate desired, and
other characteristics of your system.
Atomization Chart
Starting Fluid
Fluid Viscosity Pressure
psi (bar, MPa)
40 or more
seconds in #2 (105, 10.5)
Zahn cup*
25–40 seconds
in #2 Zahn
cup**
25 or less
seconds in #2 (35, 3.5)
Zahn cup***
* Includes fluids with 60% volume solids or greater.
Examples: high-build high-solids protective polyurethanes
and epoxies
** Includes fluids with 40 to 60% (medium) volume solids.
Examples: alkyd enamels, some protective polyurethanes
and epoxies
*** Includes fluids with 40% volume solids or less.
Examples: stains, lacquers, and decorative urethanes
1. Make sure the turbine air (TA) and atomization air
(A2) are off. Refer to Fig. 16.
2. Set the fluid pressure with the gun fluid regulator
for the type of fluid you are spraying, based on the
Starting Fluid Pressure in the Atomization Chart,
above.
Fig. 14
18 308387
Operation
Fluid Pressure
Increments
psi (bar, MPa)
1500 200
(14, 1.4)
1000 100
(70, 7) (7, 0.7)
500 100
(7, 0.7)
Gun Fluid
Regulator
3. With the turbine air (TA) off and the atomization air
(A2) off, spray a test pattern across a piece of
paper, holding the gun 12 inches (305 mm) from
the surface.
Without being concerned about the presence of
"tails", note the particle size. See Fig. 15.
4. Increase the fluid pressure by the Fluid Pressure
Increment shown in the Atomization Chart for the
type of fluid you are spraying.
5. Spray another test pattern across a piece of paper.
6. Without being concerned about the presence of
"tails", compare the particle size of the two test
patterns.
A decrease in particle size indicates improved
atomization.
7. Continue to increase the fluid pressure by the
increments shown in the chart until the particle
size no longer reduces in size; do not exceed the
gun's Maximum Fluid Pressure of 3000 psi (207
bar, 20.7 MPa).
When the particle size no longer reduces in size,
the pattern is atomized at the lowest possible fluid
pressure, but will still have tails.
8. Turn on the atomization air and adjust the air
pressure until the tails are eliminated. See Fig. 15.
NOTE: See Spray Pattern Troubleshooting on page
25 to correct spray pattern problems.
No Air
01999
Fig. 15
Tails
Too Little Air Right
Amount
of Air
0792