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

8
A7A Modular Automatic Airless Spray Gun

Single 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 fluid hoses from the
spray gun. High pressure fluid is
dangerous and can cause injection injuries.
See Figure 4. If you are using service kit 1056459,
to repair the single gun, you need only perform
steps 1- 4 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 (15) and separate the gun
module from the manifold (17).
4. Remove the nozzle nut (14) and nozzle.
5. To disassemble the gun module:
a. Remove the O-rings (16) from the module.
b. Remove the air cylinder (4), gasket (5), and
compression spring (6).
c. 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).
d. Remove the screws (13) and seat (12C).
e. Push or pull the packing cartridge out of the
gun body (10).
f. Unscrew the ball tip (12A) from the packing
cartridge stem.

Cleaning and Inspection

1. Clean the wetted parts with a compatible
cleaning solution.
Part 1072609- 02
2. Inspect the ball tip and seat. If either are worn
or damaged, replace both. The ball tip and
seat are a matched set and only sold as a kit.
3. Inspect the piston seal (8C). If it is worn or
damaged replace it.
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 body, replace the packing
cartridge.

Assembly

1. To assemble the gun module:
a. Install the O-ring (9) in the internal groove in
the gun body.
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 O-ring (12B) on the seat (12C).
f. Install the seat on the gun body and tighten
the screws (13) securely.
g. Thread the piston assembly (8) onto the
packing cartridge stem until it rests against
the gun body.
h. 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.
i. 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.
j. Install the compression spring (6) on top of
the piston.
k. Install the gasket and air cylinder. Tighten
the screws (2) securely.
2. Install the O-rings (16) in the gun body grooves.
1 3
/ to / turn, until it is
2 4
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