Nordson A7AA Reference guide

Model A7AA Air Assisted
Airless Gun
Customer Product Manual
Part 108 046C
NORDSON CORPORATION AMHERST, OHIO USA
OBSOLETE

2000 Nordson Corporation
All rights reserved
108 046C
Issued 1/00
Manual 4-20
Nordson Corporation welcomes requests for information, comments and inquiries about its products. General
information about Nordson can be found on the Internet using the following address: http://www.nordson.com.
Address all correspondence to:
Nordson Corporation
Attn: Customer Service
555 Jackson Street
Amherst, OH 44001
Notice
This is a Nordson Corporation publication which is protected by copyright. Original copyright date 1990. No part of
this document may be photocopied, reproduced, or translated to another language without the prior written consent
of Nordson Corporation. The information contained in this publication is subject to change without notice.
Trademarks
Blue Box, Can Works, Century, CleanSleeve, CleanSpray, Control Coat, Cross-Cut, Easy Coat, Econo-Coat, Excel
2000, Flow Sentry, FoamMix, Horizon, Hot Shot, Isocoil, Isocore, Iso-Flo, MEG, Nordson, the Nordson logo,
Package of Values, PowderGrid, Pro-Flo, PRX, RBX, Ready Coat, Rhino, SCF, Select Coat, Select Cure, Shur-Lok,
Smart-Coat, System Sentry, Tribomatic, Versa-Coat, Versa-Screen, and Versa-Spray
are registered trademarks of Nordson Corporation.
Accu-Jet, Auto-Flo, CanNeck, Clean Coat, CPX, EasyClean, Ink-Dot, OptiMix, PowderGrid, Pulse-Spray, Sure
Coat, Swirlcoat and Walcom are trademarks of Nordson Corporation.
Viton is a registered trademark of E.I. DuPont de Nemours & Co.

Table of Contents
i
2000 Nordson Corporation
All rights reserved 108 046C
Issued 1/00 Manual 4-20
Table of Contents
1. Safety 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Qualified Personnel 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Intended Use 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Regulations and Approvals 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Personal Safety 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
High-Pressure Fluids 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fire Safety 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Halogenated Hydrocarbon Solvent Hazards 5. . . . . . . . . . . . . . . .
Action in the Event of a Malfunction 5. . . . . . . . . . . . . . . . . . . . . . . . .
Disposal 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2. Description 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Theory of Operation 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3. Installation 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Quick-Exhaust Valve 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4. Operation 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Shutdown 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5. Maintenance 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6. Troubleshooting 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Troubleshooting Chart 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7. Repair 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gun Disassembly 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gun Assembly 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8. Parts 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using the Illustrated Parts List 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A7AA Airless Gun 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Seal Service Kit 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ball Tip With Seat Service Kit 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Recommended Spare Parts 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table of Contents
ii
2000 Nordson Corporation
All rights reserved
108 046C
Issued 1/00
Manual 4-20
9. Options 19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Nozzles and Air Cap 19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Equipment 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10. Specifications 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dimensions 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Weight 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pressures 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Model A7AA Air Assisted Airless Gun
1
2000 Nordson Corporation
All rights reserved 108 046C
Issued 1/00 Manual 4-20
Model A7AA Air Assisted Airless Gun
Read and follow these safety instructions. Task- and equipment-specific
warnings, cautions, and instructions are included in equipment
documentation where appropriate.
Make sure all equipment documentation, including these instructions, is
accessible to persons operating or servicing equipment.
Equipment owners are responsible for making sure that Nordson
equipment is installed, operated, and serviced by qualified personnel.
Qualified personnel are those employees or contractors who are trained
to safely perform their assigned tasks. They are familiar with all relevant
safety rules and regulations and are physically capable of performing
their assigned tasks.
Use of Nordson equipment in ways other than those described in the
documentation supplied with the equipment may result in injury to
persons or damage to property.
Some examples of unintended use of equipment include
using incompatible materials
making unauthorized modifications
removing or bypassing safety guards or interlocks
using incompatible or damaged parts
using unapproved auxiliary equipment
operating equipment in excess of maximum ratings
Make sure all equipment is rated and approved for the environment in
which it is used. Any approvals obtained for Nordson equipment will be
voided if instructions for installation, operation, and service are not
followed.
1. Safety
Qualified Personnel
Intended Use
Regulations and Approvals

Model A7AA Air Assisted Airless Gun
2
2000 Nordson Corporation
All rights reserved
108 046C
Issued 1/00
Manual 4-20
To prevent injury follow these instructions.
Do not operate or service equipment unless you are qualified.
Do not operate equipment unless safety guards, doors, or covers are
intact and automatic interlocks are operating properly. Do not bypass
or disarm any safety devices.
Keep clear of moving equipment. Before adjusting or servicing
moving equipment, shut off the power supply and wait until the
equipment comes to a complete stop. Lock out power and secure the
equipment to prevent unexpected movement.
Relieve (bleed off) hydraulic and pneumatic pressure before adjusting
or servicing pressurized systems or components. Disconnect, lock
out, and tag switches before servicing electrical equipment.
While operating manual spray guns, make sure you are grounded.
Wear electrically conductive gloves or a grounding strap connected to
the gun handle or other true earth ground. Do not wear or carry
metallic objects such as jewelry or tools.
If you receive even a slight electrical shock, shut down all electrical or
electrostatic equipment immediately. Do not restart the equipment
until the problem has been identified and corrected.
Obtain and read Material Safety Data Sheets (MSDS) for all materials
used. Follow the manufacturer’s instructions for safe handling and
use of materials, and use recommended personal protection devices.
Make sure the spray area is adequately ventilated.
To prevent injury, be aware of less-obvious dangers in the workplace
that often cannot be completely eliminated, such as hot surfaces,
sharp edges, energized electrical circuits, and moving parts that
cannot be enclosed or otherwise guarded for practical reasons.
Personal Safety

Model A7AA Air Assisted Airless Gun
3
2000 Nordson Corporation
All rights reserved 108 046C
Issued 1/00 Manual 4-20
High-Pressure Fluids
High-pressure fluids, unless they are safely contained, are extremely
hazardous. Always relieve fluid pressure before adjusting or servicing
high pressure equipment. A jet of high-pressure fluid can cut like a knife
and cause serious bodily injury, amputation, or death. Fluids penetrating
the skin can also cause toxic poisoning.
If you suffer a fluid injection injury, seek medical care immediately. If
possible, provide a copy of the MSDS for the injected fluid to the health
care provider.
The National Spray Equipment Manufacturers Association has created a
wallet card that you should carry when you are operating high-pressure
spray equipment. These cards are supplied with your equipment. The
following is the text of this card:
WARNING: Any injury caused by high pressure liquid can be
serious. If you are injured or even suspect an injury:
Go to an emergency room immediately.
Tell the doctor that you suspect an injection injury.
Show him this card.
Tell him what kind of material you were spraying.
MEDICAL ALERT—AIRLESS SPRAY WOUNDS: NOTE TO PHYSICIAN
Injection in the skin is a serious traumatic injury. It is important to treat
the injury surgically as soon as possible. Do not delay treatment to
research toxicity. Toxicity is a concern with some exotic coatings injected
directly into the bloodstream.
Consultation with a plastic surgeon or a reconstructive hand surgeon may
be advisable.
The seriousness of the wound depends on where the injury is on the
body, whether the substance hit something on its way in and deflected
causing more damage, and many other variables including skin
microflora residing in the paint or gun which are blasted into the wound.
If the injected paint contains acrylic latex and titanium dioxide that
damage the tissue’s resistance to infection, bacterial growth will flourish.
The treatment that doctors recommend for an injection injury to the hand
includes immediate decompression of the closed vascular compartments
of the hand to release the underlying tissue distended by the injected
paint, judicious wound debridement, and immediate antibiotic treatment.

Model A7AA Air Assisted Airless Gun
4
2000 Nordson Corporation
All rights reserved
108 046C
Issued 1/00
Manual 4-20
To avoid a fire or explosion, follow these instructions.
Ground all conductive equipment in the spray area. Use only
grounded air and fluid hoses. Check equipment and workpiece
grounding devices regularly. Resistance to ground must not exceed
one megohm.
Shut down all equipment immediately if you notice static sparking or
arcing. Do not restart the equipment until the cause has been
identified and corrected.
Do not smoke, weld, grind, or use open flames where flammable
materials are being used or stored.
Do not heat materials to temperatures above those recommended by
the manufacturer. Make sure heat monitoring and limiting devices are
working properly.
Provide adequate ventilation to prevent dangerous concentrations of
volatile particles or vapors. Refer to local codes or your material
MSDS for guidance.
Do not disconnect live electrical circuits while working with flammable
materials. Shut off power at a disconnect switch first to prevent
sparking.
Know where emergency stop buttons, shutoff valves, and fire
extinguishers are located. If a fire starts in a spray booth,
immediately shut off the spray system and exhaust fans.
Shut off electrostatic power and ground the charging system before
adjusting, cleaning, or repairing electrostatic equipment.
Clean, maintain, test, and repair equipment according to the
instructions in your equipment documentation.
Use only replacement parts that are designed for use with original
equipment. Contact your Nordson representative for parts
information and advice.
Fire Safety

Model A7AA Air Assisted Airless Gun
5
2000 Nordson Corporation
All rights reserved 108 046C
Issued 1/00 Manual 4-20
Halogenated Hydrocarbon Solvent Hazards
Do not use halogenated hydrocarbon solvents in a pressurized system
that contains aluminum components. Under pressure, these solvents
can react with aluminum and explode, causing injury, death, or property
damage. Halogenated hydrocarbon solvents contain one or more of the
following elements:
Element Symbol Prefix
Fluorine F “Fluoro-”
Chlorine Cl “Chloro-”
Bromine Br “Bromo-”
Iodine I “Iodo-”
Check your material MSDS or contact your material supplier for more
information. If you must use halogenated hydrocarbon solvents, contact
your Nordson representative for information about compatible Nordson
components.
If a system or any equipment in a system malfunctions, shut off the
system immediately and perform the following steps:
Disconnect and lock out system electrical power. Close hydraulic and
pneumatic shutoff valves and relieve pressures.
Identify the reason for the malfunction and correct it before restarting
the system.
Dispose of equipment and materials used in operation and servicing
according to local codes.
Action in the Event of a
Malfunction
Disposal

Model A7AA Air Assisted Airless Gun
6
2000 Nordson Corporation
All rights reserved
108 046C
Issued 1/00
Manual 4-20
See Figure 1. The model A7AA gun is a compact, high-cycle, air
assisted airless spray gun. The A7AA is designed to spray solvent or
waterborne coatings, and may be used in a wide variety of applications.
The wetted parts of the A7AA gun are constructed of stainless steel for
corrosion resistance. The A7AA can be used for dead-end or circulating
applications. It is also suitable for use in heated systems up to 92 C
(200 F) or ambient fluid systems.
Due to its fast trigger cycle capability, the A7AA may be used for ultra
high speed applications as well as common product finishing. Its simple
design and rugged construction provide for long service life and easy
field maintenance. In the event of a gun failure, several repair kits are
provided to reduce downtime.
0420001A
Fig. 1 Model A7AA Air Assisted Airless Gun
2. Description