Dual Gun Repair; Disassembly; Cleaning And Inspection; Assembly - Nordson A7A Customer Product Manual

10
A7A Modular Automatic Airless Spray Gun

Dual Gun Repair

WARNING: Allow only qualified personnel
to perform the following tasks. Follow the
safety instructions in this document and all
other related documentation.
WARNING: Shut off the fluid pump and
relieve the system fluid pressure before
disconnecting the gun module from the
spray gun. High pressure fluid is
dangerous and can cause injection injuries.
See Figure 4. If you are using service kit 1059498,
to repair the dual gun, you need only perform steps
1- 5 of the Disassembly procedure, and steps 2- 4
of the Assembly procedure.

Disassembly

1. Flush the spray gun with clean solvent or
cleaning solution.
2. Relieve the system fluid and air pressure.
3. Remove the screws (21). Separate the gun
module (1) from the manifolds (23).
4. Remove the O-rings (22) from the gun body
grooves (10).
5. Remove the nozzle nut (20) and nozzle.
6. To disassemble each side of the gun module:
a. Remove the air cylinder (4), gasket (5), and
compression spring (6).
b. Hold the packing cartridge stem (11) with a
wrench and remove the lock nut (7).
Unscrew the piston assembly (8) from the
stem and separate the seal nut, O-ring and
piston (8A, 8B, 8C).
c. Remove the screws (19). Separate the gun
body (10) from the manifold (16).
d. Push or pull the packing cartridge out of the
bodies.
e. Unscrew the ball tip (12A) from the packing
cartridge stem.
f. Remove the large O-ring 13, seat retainer
(14), seat (12B), and small O-ring (15) from
the manifold.
Part 1072609- 02

Cleaning and Inspection

1. Clean the wetted parts with a compatible
cleaning solution.
2. The ball tips and seats are matched sets. If
either are worn or damaged, replace both.
3. Inspect the piston seal (8C). If it is worn or
damaged replace the piston (8).
4. Inspect all gaskets and O-rings. Replace any
that are damaged, using the service kit listed in
Parts.
5. If coating material was leaking from the weep
holes in the gun bodies, replace the packing
cartridges.

Assembly

1. Assemble each side of the module as follows:
a. If removed, install the O-ring (9) in the
internal groove in the body (10).
b. Apply VC-3 thread-locking compound to the
bottom threads of the packing cartridge
stem (11).
c. Screw the ball tip (12A) onto the packing
cartridge stem.
d. Push the packing cartridge up into the gun
body.
e. Install the seat (12B), O-ring (15), and seat
retainer (14) in the manifold (16).
f. Install the O-ring (13) on the seat retainer.
g. Install the body onto the manifold and
tighten the screws (19) securely.
h. Thread the piston assembly (8) onto the
packing cartridge stem until it rests against
the gun body.
i. Thread the lock nut (7) part way down the
stem. Turn the piston assembly
counterclockwise
0.016- 0.023 inches from the gun body.
Thread the lock nut down against the piston
assembly.
j. Apply a drop of VC-3 thread-locking
compound to the lock nut threads. Hold the
packing cartridge stem with a small wrench
while tightening the lock nut against the
piston assembly.
k. Install the compression spring (6) on top of
the piston.
1 3
/ to / turn, until it is
2 4
E 2006 Nordson Corporation