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

10
A7A Single and Dual Automatic Airless Spray Guns

Repair

Disassembly

Cleaning and Inspection

Part 1072640A
WARNING: Allow only qualified personnel to perform the following tasks.
Follow the safety instructions in this document and all other related
documentation.
WARNING: Relieve trigger air pressure and system fluid pressure before
disconnecting air and fluid hoses to the spray gun. High pressure fluid is
dangerous and can cause injection injuries.
Refer to Figure 5 for both Disassembly and Assembly procedures.
1. Flush the gun with clean solvent.
2. Relieve system fluid and air pressure, then disconnect the fluid and air
lines from the gun.
3. To avoid having to reposition the gun on the mounting bar when you
reinstall it, unscrew the two screws (12) and remove the gun from the
mounting block (13). Otherwise, remove the gun from the mounting bar
by loosening the square head screw (14).
4. Disassembly order:
a. Remove the air cylinder (3).
b. Hold the packing cartridge stem with a wrench and remove the lock
nut (6). Unscrew the piston assembly (5) from the stem and
separate the seal nut, O-ring and piston (7, 8, 9).
c. Single Chamber: Remove the seat (19A−C) from the body (11).
d. Dual Chamber: Remove the body (11) from the manifold (25), then
remove the seat retainer, seat, and O-ring (22, 23, 24).
e. Push the packing cartridge (15) out of the body.
f. If replacing the ball or needle (16A−D), unscrew it from the packing
cartridge.
1. Clean the air cylinder, packing cartridge, gun body, and seat with a
compatible cleaning solution.
2. Inspect the seat and ball or needle. If either are damaged or scored,
replace them. The ball and seat (or needle and seat) are a matched set
and only sold as a kit.
3. Inspect the piston seal. If it is damaged replace the entire piston
assembly with the piston service kit.
4. Inspect all gaskets and O-rings. Replace any that are damaged.
5. If coating material was leaking from the weep holes above the fluid
fittings, replace the packing cartridge.
E 2019 Nordson Corporation