Maintenance; Troubleshooting - Nordson A7A Customer Product Manual

Maintenance

Troubleshooting

Problem
1. Leaking around nozzle
or nozzle retaining nut
2. Leaking from weep
holes in the gun body
above the fluid fittings
3. Spitting
4. On/Off cycle response
poor or gun not
opening or closing
E 2019 Nordson Corporation
A7A Single and Dual Automatic Airless Spray Guns
Flush the gun periodically to keep the fluid passageways and ball and seat
clean and free of contaminants. As required, disassemble and clean the
gun and replace any worn parts.
Make sure the trigger air is clean and dry. Lubricate the air supply if
operating at high speeds for long periods of time.
WARNING: Allow only qualified personnel to perform the following tasks.
Follow the safety instructions in this document and all other related
documentation.
NOTE: If you cannot solve your problem with the information given here,
contact your local Nordson representative for help.
Possible Cause
Dirty or damaged metal sealing
surface
Worn packing cartridge
Dirty or worn ball and seat
Actuating or trigger air lines too
long
Air trapped in fluid system
Air piston assembly worn or out of
adjustment
Low air pressure to the solenoid
valve
Trigger air lines too long
Fluid pressure too high
Corrective Action
Relieve system pressure. Remove
the nozzle retaining nut and clean or
replace the nozzle or retaining nut.
Replace the packing cartridge with
the appropriate kit. Refer to Parts.
Clean or replace the ball and seat.
Mount the solenoid on or as close as
possible to the gun. Use optional
air-release valve as shown in
Installation.
Purge air from system by opening the
ball valve at circulation valve and
draining system until no air bubbles
are seen, or spraying until spitting is
stopped.
Make sure the pump is not siphoning
air into the fluid system.
Adjust or replace the air piston
assembly.
Increase the air pressure to between
2.7−4.1 bar (40−60 psi).
Mount the solenoid on or as close as
possible to the gun or install an air
release valve.
Reduce the fluid pressure or install a
high-pressure kit. The guns will not
close if their maximum working
pressure is exceeded.
9
Part 1072640A