Nordson A7A User manual

A7A Airless Spray Gun
Customer Product Manual
Part 107 966E
NORDSON CORPORATION AMHERST, OHIO USA

E1998 Nordson Corporation
All rights reserved
107 966E
Issued 1/98
Manual 4-6
Nordson Corporation welcomes requests for information, comments and inquiries about its products.
Address all correspondence to
Nordson Corporation
555 Jackson Street
Amherst, OH 44001
Notice
This is a Nordson Corporation publication which is protected by copyright. Original copyright date 1987. 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
100 Plus, Blue Box, ChromaFlex, CleanSleeve, CleanSpray, Control Coat, Cross-Cut, Easy Coat, Econo-Coat,
Excel 2000, Flow Sentry, Isocoil, Isocore, Iso-Flo, Nordson, the Nordson logo, PRX, Pro-Flo, RBX, Ready-Coat,
Rhino, Select Coat, Select Cure, Shur-Lok, Smart Spray, System Sentry, Thread Coat, Tribomatic, and Versa-Spray
are registered trademarks of Nordson Corporation.
CPX, CanWorks, Excel 2000, PowderGrid, Pulse Spray, SCF, Versa-Coat, Versa Screen, Package of Values, and
Swirl Coat are trademarks of Nordson Corporation.
Teflon and Viton are registered trademarks of E.I. DuPont de Nemours & Co.

Table of Contents
i
E1998 Nordson Corporation
All rights reserved 107 966E
Issued 1/98 Manual 4-6
Table of Contents
1. Safety 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Safety Symbols 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Qualified Personnel 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Intended Use 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operation 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Less-Obvious Dangers 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Action in the Event of a System or Component Malfunction 8. . . . .
Maintenance and Repair 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Material and Solvent Precautions 10. . . . . . . . . . . . . . . . . . . . . . . . . .
Disposal 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2. Description 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Theory of Operation 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3. Installation 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Introduction 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mounting 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fluid Connections 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical Connections 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Optional Air-Release Valve 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4. Operation 19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5. Troubleshooting 19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Troubleshooting Chart 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6. Repair 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Single-Chamber Guns 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Disassembly 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dual-Chamber Guns 22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Disassembly 22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table of Contents
ii
E1998 Nordson Corporation
All rights reserved
107 966E
Issued 1/98
Manual 4-6
7. Parts 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using the Illustrated Parts List 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Standard A7A Gun 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stainless Steel A7A Gun 27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
High-Speed A7A Gun 28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tapered Needle and Seat A7A Gun 29. . . . . . . . . . . . . . . . . . . . . . . .
Compound A7A Gun 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Compound and Extended Valve A7A Gun 32. . . . . . . . . . . . . . . . . . .
Extended Valve A7A Gun 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dual-Chamber A7A Gun 34. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dual-Chamber Stainless Steel Drum Coating A7A Gun 36. . . . . . .
Standard Dual-Chamber Angled A7A Gun 38. . . . . . . . . . . . . . . . . .
Stainless Steel Dual-Chamber Angled A7A Gun 40. . . . . . . . . . . . .
Repair Kit, Piston with Seals 41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Service Kit, Needle and Seat, Tapered 41. . . . . . . . . . . . . . . . . . . . . .
Repair Kit, Needle and Seat, with O-rings 41. . . . . . . . . . . . . . . . . . .
Service Kit, Needle and Seat, Extended 42. . . . . . . . . . . . . . . . . . . .
Service Kit, Needle and Seat, with Retainer 42. . . . . . . . . . . . . . . . .
Service Kit, Ball and Seat 42. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Service Kit, Ball and Seat, with Retainer 43. . . . . . . . . . . . . . . . . . . .
Service Kit, Ball and Seat, with Retainer 43. . . . . . . . . . . . . . . . . . . .
Replacement Packing Cartridges 43. . . . . . . . . . . . . . . . . . . . . . . . . .
Conversion Kit, Air Cylinder with Detent Adjustment 44. . . . . . . . . .
Conversion Kit, High Pressure 45. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Retrofit Kit, Dual-Chamber A7A Gun 46. . . . . . . . . . . . . . . . . . . . . . .
Conversion Kit, Standard Dual-Chamber Angled A7A Gun 47. . . .
Conversion Kit, Stainless Steel Dual-Chamber,
Angled A7A Gun 47. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Recommended Spare Parts 49. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8. Specifications 50. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9. Options 50. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

A7A Airless Spray Gun
1
E1998 Nordson Corporation
All rights reserved 107 966E
Issued 1/98 Manual 4-6
A7A Airless Spray Gun
This section contains general safety instructions for using your Nordson
equipment. Task- and equipment-specific warnings are included in other
sections of this manual where appropriate. Note all warnings and follow
all instructions carefully. Failure to do so may result in personal injury,
death, or property damage.
To use this equipment safely,
Sread and become familiar with the general safety instructions
provided in this section of the manual before installing, operating,
maintaining, or repairing this equipment.
Sread and carefully follow the instructions given throughout this manual
for performing specific tasks and working with specific equipment.
Sstore this manual within easy reach of personnel installing, operating,
maintaining, or repairing this equipment.
Sfollow all applicable safety procedures required by your company,
industry standards, and government or other regulatory agencies.
Refer to the National Fire Protection Association (NFPA) standard 33
and to federal, state, regulatory agency, and local codes for rules and
regulations covering installation and operation of spray systems.
Sobtain and read Material Safety Data Sheets (MSDS) for all materials
used.
Become familiar with the safety symbols presented in this section. These
symbols will alert you to safety hazards and conditions that may result in
personal injury, death, or property and equipment damage.
WARNING: Failure to observe this warning may result in
personal injury, death, or equipment damage.
1. Safety
Safety Symbols

A7A Airless Spray Gun
2
E1998 Nordson Corporation
All rights reserved
107 966E
Issued 1/98
Manual 4-6
WARNING: Risk of electrical shock. Failure to observe this
warning may result in personal injury, death, or equipment
damage.
WARNING: Disconnect equipment from line voltage. Failure to
observe this warning may result in personal injury, death, or
equipment damage.
WARNING: Risk of explosion or fire. Fire, open flames, and
smoking prohibited.
WARNING: Wear protective clothing, safety goggles, and
approved respiratory protection. Failure to observe may result
in serious injury.
WARNING: Hot! Risk of burns. Wear heat-protective clothing,
safety goggles with side shields and/or heat-protective gloves
depending on the symbol shown.
WARNING: System or material pressurized. Relieve pressure.
Failure to observe this warning may result in serious injury
or death.
WARNING: Injection. Do not point this device at yourself or
other personnel. Failure to observe this warning may result in
serious injury or death.
Safety Symbols (contd.)

A7A Airless Spray Gun
3
E1998 Nordson Corporation
All rights reserved 107 966E
Issued 1/98 Manual 4-6
CAUTION: Failure to observe may result in equipment
damage.
CAUTION: Hot surface. Failure to observe may result in
burns.
“Qualified personnel” is defined here as individuals who thoroughly
understand the equipment and its safe operation, maintenance, and
repair. Qualified personnel are physically capable of performing the
required tasks, familiar with all relevant safety rules and regulations, and
have been trained to safely install, operate, maintain, and repair the
equipment. It is the responsibility of the company operating this
equipment to see that its personnel meet these requirements.
WARNING: Use of this equipment in ways other than
described in this manual may result in personal injury, death, or
property and equipment damage. Use this equipment only as
described in this manual.
Nordson Corporation cannot be responsible for injuries or damages
resulting from nonstandard, unintended applications of its equipment.
This equipment is designed and intended only for the purpose described
in this manual. Uses not described in this manual are considered
unintended uses and may result in serious personal injury, death, or
property damage. Unintended uses may result from taking the following
actions:
Smaking changes to equipment that have not been recommended or
described in this manual or using parts that are not genuine Nordson
replacement parts
Sfailing to make sure that auxiliary equipment complies with approval
agency requirements, local codes, and all applicable safety standards
Susing materials or auxiliary equipment that are inappropriate or
incompatible with your Nordson equipment
Sallowing unqualified personnel to perform any task
Safety Symbols (contd.)
Qualified Personnel
Intended Use

A7A Airless Spray Gun
4
E1998 Nordson Corporation
All rights reserved
107 966E
Issued 1/98
Manual 4-6
Read the installation section of all system component manuals before
installing your Nordson equipment. A thorough understanding of system
components and their requirements will help you to install this equipment
safely and efficiently.
WARNING: Failure to follow these safety procedures can result
in personal injury or death.
SAllow only qualified personnel to install Nordson equipment.
SUse only approved equipment. Using unapproved equipment in an
approved system may void agency approvals.
SMake sure all equipment is rated and approved for the environment in
which you are using it.
SFollow all instructions for installing components and accessories.
SInstall all electrical, pneumatic, gas, and hydraulic connections to
local code.
SInstall locking, manual, shutoff valves in the air supply lines to the
system. This allows you to relieve air pressure and lock out the
pneumatic system before undertaking maintenance and repairs.
SInstall a locking disconnect switch or breaker in the service line ahead
of any electrical equipment.
SUse only electrical wire of sufficient gauge and insulation to handle
the rated current demand. All wiring must meet local codes.
SGround all electrically conductive equipment. Ungrounded
conductive equipment can store a static charge which could ignite a
fire or cause an explosion if a hot spark is discharged.
SRoute electrical wiring, electrostatic cables, and air hoses and tubing
along a protected path. Make sure they will not be damaged. Do not
bend electrostatic cables around a radius of less than 6 in. (152 mm).
SInstall safety interlocks and approved, fast-acting fire detection
systems. These shut down the spray system and any flammable
liquid supply if a ventilation or electrical problem occurs, a fire is
detected, or other emergency situation develops.
Installation

A7A Airless Spray Gun
5
E1998 Nordson Corporation
All rights reserved 107 966E
Issued 1/98 Manual 4-6
SMake sure the spray area floor is conductive to ground and that the
operator’s platform is grounded.
SUse only designated lifting points or lugs to lift and move heavy
equipment. Always balance and block loads when lifting to prevent
shifting. Lifting devices must be inspected, certified, and rated for a
greater weight than the equipment being lifted.
SDo not use unapproved fluid hoses. Solvents may cause them to
deteriorate rapidly which may allow flammable or pressurized material
to escape.
SProtect components from damage, wear, and harsh environmental
conditions.
SAllow ample room for maintenance, material supply container drop-off
and loading, panel accessibility, and cover removal.
SProtect equipment with safety devices as specified by applicable
safety regulations.
SIf safety devices must be removed for installation, install them
immediately after the
Swork is completed and check them for proper functioning.
Only qualified personnel, physically capable of operating the equipment
and with no impairments to their judgement or reaction times, should
operate this equipment.
Read all component manuals before operating this equipment. A
thorough understanding of system components and their operation will
help you operate the system safely and efficiently.
SUse this equipment only in the environments for which it is rated. Do
not operate this equipment in humid, flammable, or explosive
environments unless it has been rated for safe operation in these
environments.
SBefore starting this equipment, check all safety interlocks,
fire-detection systems, and protective devices such as panels and
covers. Make sure all devices are fully functional. Do not operate the
system if these devices are not working properly. Do not deactivate
or bypass automatic safety interlocks, locked-out electrical
disconnects, or pneumatic valves.
Installation (contd.)
Operation

A7A Airless Spray Gun
6
E1998 Nordson Corporation
All rights reserved
107 966E
Issued 1/98
Manual 4-6
SKnow where EMERGENCY STOP buttons, shutoff valves, and fire
extinguishers are located. Make sure they work. If a component
malfunctions, shut down and lock out the equipment immediately.
SBefore operating, make sure all conductive equipment, objects being
sprayed, and fluid containers are connected to a true earth ground.
SNever operate equipment with a known malfunction or leak.
SNever point handguns or applicator nozzles at yourself or other
persons.
SNever touch exposed electrical connections on equipment while the
power is ON.
SDo not operate the equipment at pressures higher than the rated
maximum working pressure of any component in the system.
SShut off moving equipment before taking measurements or inspecting
workpieces.
SKnow the pinch points, temperatures, pressures, and material
composition for all equipment that you are working with. Recognize
potential hazards associated with these and exercise appropriate
caution.
SWear shoes with conductive soles, such as leather, or use grounding
straps to maintain a connection to ground when working with or
around electrostatic equipment.
SDo not wear or carry metallic objects (jewelry or tools) while working
with or around electrostatic equipment. Ungrounded metal can store
a static charge and cause harmful shocks.
SMaintain skin-to-metal contact between your hand and the gun handle
to prevent shocks while operating manual electrostatic spray guns. If
wearing gloves, cut away the palm or fingers.
SShut off electrostatic power supplies and ground gun electrodes
before making adjustments to powder spray guns.
SIf you notice electrical arcing in a spray area, shut down the system
immediately. An arc can cause a fire or explosion.
SKeep parts of the body or loose clothing away from rotating parts.
Remove personal jewelry and cover or tie back long hair.
Operation (contd.)

A7A Airless Spray Gun
7
E1998 Nordson Corporation
All rights reserved 107 966E
Issued 1/98 Manual 4-6
SWear National Institute of Occupational Safety and Health (NIOSH)
approved respirators while operating spray equipment and when
performing maintenance and cleaning tasks.
SWear eye protection when operating spray equipment.
SWear gloves and protective clothing to protect your skin from
materials.
SKeep paint pumps, pressure pots, and containers of flammable
coating materials or solvents far enough away from spray booths to
prevent their inclusion in a booth fire.
SDo not smoke in the spray area. A lit cigarette could ignite a fire or
cause an explosion.
STreat all high-pressure fittings and hoses as if they could leak.
High-pressure compressed air can be injected under the skin and
cause serious injury or death.
SDo not use materials that will corrode the equipment.
SDo not attempt to operate electrical equipment if standing water is
present.
SWash exposed skin frequently with soap and water, especially before
eating or drinking. Do not use solvents to remove coating materials
from your skin.
Operators should also be aware of less-obvious dangers in the workplace
that often cannot be completely eliminated:
Sexposed surfaces on the equipment which may be hot or have sharp
edges and cannot be practically safeguarded
Selectrical equipment which may remain energized after the equipment
has been shut off
Svapors and materials which may cause allergic reactions or other
health problems
Sautomatic hydraulic, pneumatic equipment, or mechanical parts that
may move without warning
Sunguarded, moving mechanical assemblies
Operation (contd.)
Less-Obvious Dangers

A7A Airless Spray Gun
8
E1998 Nordson Corporation
All rights reserved
107 966E
Issued 1/98
Manual 4-6
Do not operate a system that contains malfunctioning components. If a
component malfunctions, turn the system OFF immediately.
SDisconnect and lock out electrical power. Close and lock out
hydraulic and pneumatic shutoff valves and relieve pressures.
SAllow only qualified personnel to make repairs. Repair or replace the
malfunctioning component according to instructions provided in its
manual.
Allow only qualified personnel to perform maintenance, troubleshooting,
and repair tasks. Only persons who are properly trained and familiar with
Nordson equipment are permitted to service this equipment.
SAlways wear appropriate protective clothing and use safety devices
when working on this equipment.
SFollow the recommended maintenance procedures in your equipment
manuals.
SDo not service or adjust any equipment unless another person trained
in first aid and CPR is present.
SDisconnect, lock out, and tag electrical power at a disconnect or
breaker in the service line ahead of electrical equipment before
servicing.
SRelieve air and fluid pressures before servicing equipment. Follow
the specific instructions in this manual.
SUse only genuine Nordson replacement parts. Using unapproved
parts or making unapproved modifications to equipment may void
agency approvals and create safety hazards.
WARNING: Note the flash point of the cleaning solvent used.
Only use controlled methods and equipment, such as
temperature-controlled or explosion-protected heaters, to heat
cleaning solvent. Observe explosion-prevention regulations
and follow applicable safety instructions.
SRefer to the MSDS before using solvents to clean this equipment.
The MSDS will provide use, storage, and disposal information about
the solvent. Read this information carefully and follow instructions.
A
ction in the Event of a System
or Component Malfunction
Maintenance and Repair

A7A Airless Spray Gun
9
E1998 Nordson Corporation
All rights reserved 107 966E
Issued 1/98 Manual 4-6
SNever use an open flame to clean the unit or components of the unit.
SDo not store flammable materials in the spray area or room. Keep
paint pumps, pressure pots, and containers of flammable coating
materials or solvents far enough away from spray booths to prevent
their inclusion in a booth fire. If a fire or explosion occurs, flammable
materials in the area will increase the chances and the extent of
personal injuries and property damage.
SMake sure that the room where you are working is sufficiently
ventilated. Avoid breathing vapors over prolonged periods of time.
SCheck interlock systems periodically to ensure their effectiveness.
WARNING: Operating faulty or electrostatic equipment is
hazardous and can cause electrocution, fire, or explosion.
Make resistance checks part of your periodic maintenance
program.
SCheck all ground connections periodically with a megohm meter.
Resistance to ground must not exceed one megohm. If sparks or
arcing occur, shut down the system immediately.
SConnect all disconnected equipment ground cables and wires after
servicing the equipment. Ground all conductive equipment.
WARNING: Service lines connected to panel disconnect
switches will still be energized unless power is shut off at
another disconnect ahead of the panel. Make sure the power is
off before servicing. Wait 5 minutes for capacitors to discharge
after shutting off the electrical power.
STurn off the electrostatic power supply and ground the gun electrode
before adjusting or cleaning the nozzles, fluid tips, or air caps.
SIf a “power on” test is required, perform the test carefully and then
shut off and lock out power as soon as the test is over.
SNever troubleshoot the power supply without first disconnecting all
external power supplies and discharging the high-voltage capacitors
with an insulated screwdriver.
SGround electrodes and electrostatic cable ends before touching them.
Maintenance and Repair (contd.)

A7A Airless Spray Gun
10
E1998 Nordson Corporation
All rights reserved
107 966E
Issued 1/98
Manual 4-6
SDo not attempt to service electrical equipment if there is standing
water present. Do not service electrical equipment in a high-humidity
environment.
SUse tools with insulated handles when working with electrical
equipment.
SKeep high-voltage connection points clean and insulated with
dielectric grease or oil.
SDo not attempt to service a moving piece of equipment. Shut off the
equipment and lock out power. Secure equipment to prevent
uncontrolled movement.
WARNING: Hot! Risk of burns. Wear heat-protective clothing,
eye protection with side shields and/or heat-protective gloves.
Heated materials may cause severe burns on contact. Remember that
some materials, even solid materials, may retain heat for some time. If
you are burned by a heated material, immediately cool the affected skin
with lots of cool, clean water. Do not try to remove hot, melted material
from the skin. Seek immediate medical attention.
High-pressure fluids, unless they are safely contained, are extremely
hazardous. A jet of high-pressure fluid can act like a knife or needle,
penetrate skin and muscle, and inject itself into your body. Injected fluids
can cause toxic poisoning.
Do not treat an injection injury as minor. Seek medical care immediately.
Inform the medical staff at the hospital that you have an injection injury
and identify the fluid that was injected. If possible, give the doctor copies
of the MSDS for the injected fluid and for any additives, such as solvents,
that are in the injected fluid.
Also, Nordson recommends that you carry a National Safety Equipment
Manufacturers Association (NSEMA) wallet card to give to emergency
medical staff in the event of an injection injury. These cards are supplied
with the equipment. Additional cards are available free from Nordson
Corporation.
Maintenance and Repair (contd.)
Material and Solvent
Precautions

A7A Airless Spray Gun
11
E1998 Nordson Corporation
All rights reserved 107 966E
Issued 1/98 Manual 4-6
WARNING: Injection hazard. Do not go near a known leak in a
hose or fitting, and stay clear of all spray nozzles or orifices. Do
not point an applicator at yourself or other personnel. The
high-pressure fluid into the body causing serious injury or
death.
To prevent an injection injury, take some basic safety precautions when
operating your equipment.
SAlways handle spray applicators carefully. Do not point a pressurized
gun at yourself or other personnel.
SNever place hands, fingers, or other parts of your body directly over a
spray nozzle or in front of a leak in a high-pressure system.
SNever “back-flush” the nozzles. Blocking a nozzle causes the
high-pressure fluid to reverse direction and can lead to an injection
injury.
SAlways relieve system pressure before servicing equipment. Trigger
all applicators and bleed off system pressure.
Halogenated hydrocarbon solvents can cause an explosion when used
with aluminum components in a pressurized fluid pumping system
(pumps, heaters, filters, valves, spray guns, and tanks). The explosion
could cause serious bodily injury, death, or substantial property damage.
No available stabilizers will prevent this violent reaction from happening.
WARNING: Never use halogenated hydrocarbon solvents to
clean aluminum parts or to flush any system. Cleaning agents,
coatings and paints, or adhesives may contain halogenated hy-
drocarbon solvents. Obtain and read the MSDS for each mate-
rial and solvent being used.
SUse nonhalogenated solvents.
SContact your solvent supplier to determine whether your existing
materials and solvents contain halogenated hydrocarbons or to obtain
a suitable, nonhalogenated hydrocarbon solvent for cleaning and
flushing your system.
Material and Solvent
Precautions
(contd.)

A7A Airless Spray Gun
12
E1998 Nordson Corporation
All rights reserved
107 966E
Issued 1/98
Manual 4-6
SSee Table 1. Check the labels on your solvent containers.
Halogenated hydrocarbon solvents can be recognized if any of the
following elements are listed in the name of the product or as an
ingredient:
Element Symbol Prefix
Fluorine F “Fluoro-”
Chlorine Cl “Chloro-”
Bromine Br “Bromo-”
Iodine I “Iodo-”
If you are now using halogenated hydrocarbon solvents in pressurized
systems with aluminum components, perform the following steps:
SPump the system empty, shut off the pumps, and relieve the system
pressure.
SDisassemble and inspect the system components. Replace any
damaged or corroded parts.
SThoroughly clean all noncorroded parts with nonhalogenated
hydrocarbon.
SContact your coatings, solvent, or adhesive supplier for a
nonhalogenated solvent to thoroughly flush the entire system before
operating it.
SIf you must continue to use halogenated hydrocarbon solvents,
consult your Nordson representative about compatible Nordson
components.
Material and Solvent
Precautions
(contd.)

A7A Airless Spray Gun
13
E1998 Nordson Corporation
All rights reserved 107 966E
Issued 1/98 Manual 4-6
Table 1 Solvents Containing Halogenated Fluids
Chlorinated Solvents Iodinated Solvents Brominated Solvents Fluorocarbon Solvents
Carbon Tetrachloride Ethyl Iodide Ethylene Dibromide Dichlorofluoromethane
Chloroform Methyl Iodide Methyl Bromide Trichlorofluoromethane
Ethylene Dichloride N-butyl Iodide Methylene Chlorobromide Freon
Methylene Chloride Propyl Iodide
1-1-1 Trichloroethane
Monochlorobenzene
Orthodichlorobenzene
Perchloroethylene
Trichloroethylene
Dispose of equipment and materials used in operation and cleaning
according to your local regulations.
Material and Solvent
Precautions
(contd.)
Disposal

A7A Airless Spray Gun
14
E1998 Nordson Corporation
All rights reserved
107 966E
Issued 1/98
Manual 4-6
See Figure 1. The Nordson model A7A automatic gun is a compact,
high-cycle, airless spray gun designed to spray solvent or waterborne
coatings. Because of its fast trigger cycle capability, the A7A gun may be
used for common product finishing as well as ultra-high speed
applications.
A7A guns are constructed of standard (aluminum) or stainless steel and
are available in both single- and dual-chamber models. The
dual-chamber models permit the user to quickly switch between two
different coatings or products with no downtime. You can also purchase
several special models such as high-speed, compound, valved
extension, and dual-chamber angled to fit your application needs.
Several service kits that may reduce downtime are available for
purchase. Retrofit kits that convert two single chamber A7A guns to one
dual-chamber model or to a dual-chamber angled model are also
available. Refer to the
Parts section for details the part numbers needed
to purchase service and retrofit kits.
0406001A
1
3
2
Fig. 1 A7A single- and A7A dual-chamber guns
1. Fluid in and out—1/2-20 37_JIC 2. Air in—1/8NPT female 3. Fluid in and out—1/2-20 37_JIC
2. Description

A7A Airless Spray Gun
15
E1998 Nordson Corporation
All rights reserved 107 966E
Issued 1/98 Manual 4-6
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.
0406005A
1
21
5
7
6
4
Fig. 2 Operation of the A7A gun
1. Street elbow (air entry point)
2. Piston assembly
3. Packing cartridge
4. Needle
5. Fluid fittings (coating entry point)
6. Seat
7. Nozzle nut
T
heory of Operation

A7A Airless Spray Gun
16
E1998 Nordson Corporation
All rights reserved
107 966E
Issued 1/98
Manual 4-6
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: Before installing the A7A gun, ensure that all
pressure is relieved and electrical power is removed from the
system.
NOTE: The fluid line to this gun requires the installation of an approved
pressure relief device set at 117 bar (1700 psi), or at 207 bar (3000 psi)
when using the high pressure kit. The fluid supply hose used with this
gun must have a minimum burst pressure of 117 bar (1700 psi), or
207 bar (3000 psi) when using the high pressure kit.
See Figure 3. The A7A gun is typically used as part of a larger spraying
system. A typical installation is shown below.
0406003A
3 4 5 6
7
9
10
8
1
11
2
Fig. 3 Typical A7A installation
1. Pump
2. Heaters
3. Filter
4. Solenoid
5. Regulator
6. Air
7. A7A gun
8. Ball valves
9. Circulation valve
10. Drain off
11. Coating
3. Installation
Introduction