Theory Of Operation - Nordson A7A Product Manual

Theory of Operation

1998 Nordson Corporation
All rights reserved
WARNING: Allow only qualified personnel to perform the
following tasks. Observe and follow the safety instructions in
this document and all other related documentation.
WARNING: Do not point this device at yourself or other
personnel. Failure to observe this warning may result in serious
injury or death.
The single-chamber A7A gun applies only one coating during an
application operation. The dual-chamber A7A gun, because of its design,
is able to apply two different coatings or substances during an application
operation. With a dual-chamber gun, however, only one chamber is
activated at any time.
See Figure 2. This figure shows a cutaway view of the inner workings of
a dual-chamber A7A gun. The operation of the single-chamber gun is
similar, since the dual-chamber A7A gun is essentially two
single-chamber A7A guns sharing a single nozzle.
When the gun is triggered, air enters at the street elbow (1). This air lifts
the piston assembly (2) and allows the packing cartridge (3) and the
needle (4) to rise. The coating to be sprayed, entering at the fluid
fittings (5), may then pass through the opening in the seat (6) to the
nozzle nut (7). When the air pressure is removed, the needle returns to
the seat and stops the flow of the coating material.
2
1
4
6
Fig. 2 Operation of the A7A gun
1. Street elbow (air entry point)
2. Piston assembly
3. Packing cartridge
4. Needle
107 966E
Issued 1/98
A7A Airless Spray Gun
1
5
7
5. Fluid fittings (coating entry point)
6. Seat
7. Nozzle nut
Manual 4-6
15
0406005A