Hitachi AA 2000 - Manual (Page 8)

8ą307-586
Operation
How the Air-Assisted Airless Spray Gun
Operates
The air-assisted airless spray gun combines airless
and air spraying concepts. The spray tip shapes the
fluid into a fan pattern, as does a conventional airless
spray tip. Air from the air cap further atomizes the fluid
and completes the atomization of the paint tails into
the pattern to produce a more uniform pattern. The
pattern adjustment valve controls the width of the
pattern.
Note that the air-assisted airless spray gun differs from
an air spray gun in that increasing the pattern air
reduces the pattern width. To increase the pattern
width, less pattern air or a larger size tip must be used.
The spray gun has a built-in lead and lag operation.
When triggered, the gun begins emitting air before the
fluid is discharged. When the trigger is released, the
fluid stops before the air flow stops. This helps assure
the spray is atomized and prevents fluid buildup on the
air cap.
Select a Spray Tip and Air Cap
The fluid output and pattern width depend on the size
of the spray tip, the fluid viscosity, and the fluid pres-
sure. Use the Spray Tip and Air Cap Selection
Charts, on pages 18 and 19, as a guide for selecting
an appropriate spray tip and air cap for your applica-
tion.
NOTE:
D
Using a Fine Finish Spray Tip may improve the
finish of certain urethanes, clearcoats, or light-
weight air-dry enamels. Refer to the Fine Finish
Spray Tip Selection Chart on page 19.
D
If you are applying a solid stream of fluid, such as
mastics or sealants, refer to the Solid Stream
Spray Tip Selection Chart on page 19.
D
When spraying at fluid pressures below 500 psi (35
bar) or spraying light viscosity fluids, use optional
fluid needle 220–413 (see page 20). The standard
needle may not provide positive shut off at those
pressures or for such fluids.
D
When spraying acid catalyzed varnishes, use
optional fluid needle 222–497 (see page 20). Using
a standard needle may decrease needle life and
leakage may occur.
Install a Spray Tip
WARNING
INJECTION HAZARD
To reduce the risk of a fluid injection
injury, follow the Pressure Relief Proce-
dure on page 7 before removing or
installing a spray tip.
Install a spray tip in the gun. The air cap and spray tip
position determines the direction of the spray pattern.
Rotate the air cap (the spray tip rotates with it) as
needed for the desired spray pattern direction. See
Fig. 3.
Fig. 3
Vertical Spray Pattern Horizontal Spray Pattern