DeVilbiss JGA Operating instructions

HOW DOES YOUR SPRAY GUN SHAPE UP?
No matter how experienced the sprayer, merely
triggering and moving a gun in space will not
reveal any of the performance characteristics vital
to a top quality finish. A simple brief static spray
pattern test will immediately highlight any
potential problems before the gun is used on the
painstakingly prepared workpiece or vehicle.
Follow the procedure explained below and
compare the pattern to our examples. If your
result resembles the examples then look at the
corrective measures before you apply paint to the
workpiece.
(1) Ensure that you have the correct Air Cap, Fluid
Tip and Needle set-up on the gun to match the
material being applied.
(2) Tape a piece of brown paper (approx. ½ metre /
20” square) onto the spray booth wall at shoulder
height.
(3) Having set the gun at the recommended inlet or
atomising air pressure, hold it at he correct target
distance and spray at the paper without moving the
gun.
Normal Pattern – Ready
to Spray Intermittent Spray Fan or Fluttering
Good balance and uniformity
?Symmetrical pattern shape
?Good working height and
width
?Uniform distribution of
material (Verify by
horizontal spray-out)
?Air in the fluid passageways
?Insufficient paint in the cup
?Fluid tip loose
?Fluid needle packing or packing
screw loose
?Cup vent hole clogged
Banana Pattern Heavy Top or Bottom
Pattern
?Air cap horn hole dirty or
damaged
?Test spray pattern, rotate
180oand test again to
isolate horn hole cause
location
?Clean air cap thoroughly
?Replace air cap if necessary
?Fluid tip or cap dirty or
damaged
?Test spray pattern, rotate 180o
and test again to isolate cause.
?Clean both items thoroughly
?Replace Fluid tip or Air cap if
necessary
Single Split Pattern Centre Heavy Ellipse
?Too much air for fluid
quantity used
?Reduce air pressure at
regulator
?Increase fluid flow by
changing fluid tip size
opening needle control
knob
?Bad air or paint setting
?Viscosity too high – thin with
solvent
?Fluid flow too high – reduce
?Air pressure too low – increase
Double Split Pattern Ball End Heavy Pattern
?Too much air for fluid
quantity used
?Reduce air pressure at
regulator
?Increase fluid flow by
changing fluid tip size or
opening needle control
knob
?Too much fluid flow
?Change fluid tip for smaller size
?Reduce flow using fluid needle
control
?Reduce fan size using fan
control
STATIC PATTERN TEST
Having examined the vertical spray pattern for uniformity of shape and size, now turn the air cap through 90oand static spray
a horizontal pattern making sure you trigger for long enough to load the shape with material. Then watch to see the formation
of the run-outs of material across the full width of the spray pattern.
This will highlight how well the material is distributed throughout the spray pattern. If the run-out is more obvious at the
centre or at the ends then this indicates a problem.
TYPICAL GOOD PATTERN RUN-OUT TYPICAL BAD PATTERN RUN-OUT

MAINTENANCE & TROUBLESHOOTING PAGE 1
MAINTENANCE & TROUBLESHOOTING PAGE 1
Spray gun Maintenance and
Troubleshooting Guide
(JGA)
IMPORTANT: Before using the gun for the first time, tighten the needle
packing until the needle starts to bind. Then loosen the packing nut just
enough so that the needle moves freely.
The following hazards may occur during the normal use of this equipment. Please read the
following chart before using the equipment.
Area Hazard Safeguard
Tells where hazards may occur. Tells where hazard is. Tells how to avoid the hazard
Spray Area-
Fire Hazard Solvent and coatings can be highly flammable or combustible especially
when sprayed.
Adequate exhaust must be provided to
keep air free of accumulations of flammable
vapours.
Smoking must never be allowed in the
spray area.
Fire extinguishing equipment must be
present in the spray area.
Solvent Spray During cleaning and flushing, solvents
can be forcefully expelled from fluid and
air passageways. Some solvents can
cause eye injury.
Wear eye protection
Toxic Substances Certain materials may be harmful if
inhaled, or if there is contact with the
skin.
Follow the requirements of the Material
Safety Data Sheet supplied by your coating
material manufacturer.
Adequate exhaust must be provided to
keep the air free of accumulations of toxic
materials.
Use a mask or respirator whenever there is
a chance of inhaling sprayed materials.
This mask must be compatible with the
material being sprayed and its
concentration.
Explosion Hazard-
Incompatible Materials Halogenated Hydrocarbon solvents - for example: Methylene Chloride and 1,1,1 -
Trichloroethane are not chemically
compatible with the aluminium which may
be used in many system components.
The chemical reaction caused by these
solvents reacting with aluminium can
become violent and lead to an equipment
explosion.
Guns with stainless steel fluid passages
may be used with these solvents. However,
Aluminium is widely used in other spray
application equipment - such as material
pumps, cups and regulators, valves, etc.
Check all other equipment items before use
and make sure they can also be used
safely with these solvents. Read the label
or data sheet for the material you intend to
spray. If in doubt as to whether or not a
coating or cleaning or cleaning material is
compatible, contact your material supplier.
WARNING

MAINTENANCE & TROUBLESHOOTING PAGE 2
MAINTENANCE & TROUBLESHOOTING PAGE 2
SPRAY FAULTS
Condition Cause Correction
Improper spray pattern Gun Improperly adjusted.
Dirty air cap
Fluid tip obstructed
Sluggish needle
Readjust gun, follow instructions carefully.
Clean air cap.
Clean
Lubricate (see lubrication section) or
loosen packing nut.
Heavy top or bottom pattern Material build-up on air cap, partially
plugged horn holes, centre holes or jets.
Material build-up on fluid tip or partially
plugged fluid tip
Soak cap or tip in suitable solvent and wipe
clean. To clean orifice, use a broom straw
or toothpick. Never use a wire or hard
instruments. This damages holes and
distorts spray pattern.
Heavy right or left side pattern Note: To determine where material build-up is, invert cap and test spray. If pattern shape
stays in same position, the condition is caused by material build-up on fluid tip. If pattern
changes with cap movement, the condition is in the air cap.
Heavy centre pattern Too much material
Material too thick
Reduce fluid flow by turning fluid needle
adjusting screw clockwise. Reduce fluid
pressure or increase atomisation pressure.
Thin
Intermittent or ‘fluttering’ spray fan Loose fluid tip
Fluid tip not seated correctly in gun head
Gun (with cup) tipped at excessive angle.
Obstructed fluid passage or hose.
Loose or cracked fluid tube in cup or
tank.
Insufficient fluid in cup or pressure tank.
Too heavy fluid for suction feed.
Dry or worn packing or loose packing nut.
Plugged vent on suction feed cup.
Gun fluid inlet loose or not sealed/seated
correctly
Fluid hose or cup not fitted correctly to
gun fluid inlet connector
Tighten to 17 Nm (150 ibf/in)
Remove tip, clean components, check
cone seating on tip and gun for damage or
contamination
Do not tip excessively or rotate fluid tube.
Clean
Tighten or replace
Fill cup or tank
Thin material or change to pressure feed
Lubricate or replace. Tighten
Clean vent hole in cup lid.
Tighten to 8 Nm (70 lbf/in)
Remove, check mating surfaces and re-
tighten

MAINTENANCE & TROUBLESHOOTING PAGE 3
MAINTENANCE & TROUBLESHOOTING PAGE 3
SPRAY FAULTS
Condition Cause Correction
Split spray pattern Not enough material or too high
atomisation pressure Reduce air pressure or increase fluid flow by turning fluid needle adjusting screw
counterclockwise or increase fluid
pressure on pressure feed container.
Excessive bounce-back Too much atomisation air pressure
Gun too far from surface
Improper technique i.e. arcing, & fanning
the gun
Reduce air pressure
Check distance (normally 6-8”)
Move at moderate pace, parallel to work
surface
FINISH FAULTS
Runs and sags Too much material flow
Material too thin
Gun tilted on an angle
Adjust gun or reduce fluid pressure
Mix properly or apply light coats
Hold gun at right angle to work and adapt
to proper gun technique
Thin, sandy coarse finish drying before it
flows out. Gun too far from surface
Too much air pressure
Improper thinner being used
Check distance (normally 6-8”)
Reduce air pressure and check spray
pattern
Follow paint manufacturers mixing
instructions
Thick dimpled finish “orange peel”. Too
much material coarsely atomised. Gun too close to surface
Air pressure too low
Improper thinner being used
Material not properly mixed
Surface rough, oily, dirty
Check distance (normally 6-8”)
Increase air pressure or reduce fluid
pressure
Follow paint manufacturers mixing
instructions
Follow paint manufacturers mixing
instructions
Properly clean and prepare

MAINTENANCE & TROUBLESHOOTING PAGE 4
MAINTENANCE & TROUBLESHOOTING PAGE 4

MAINTENANCE & TROUBLESHOOTING PAGE 5
MAINTENANCE & TROUBLESHOOTING PAGE 5
GUN FAULTS
Condition Cause Correction
A
Will not spray No air pressure at gun
Internal mix or pressure feed air cap used
with suction feed
Fluid pressure too low with internal mix
cap and pressure tank
Fluid needle adjusting screw not open
enough
Fluid too heavy for suction feed
Check air supply and air lines
Change to proper suction feed air cap
Increase fluid pressure at tank
Open fluid needle adjusting screw
Thin material or change to pressure feed.
AGun ‘spits’ paint when triggering on
and off Incorrect needle fitted to gun
Excessive needle wear
Excessive fluid tip wear
Check tip/needle selection chart and fit
correct item
Replace with new needle
Replace with new fluid tip
ASmall air leak from air cap when
gun is not triggered Air valve contaminated and not correctly seating
Air Valve seal damaged or missing
Remove valve and thorougly clean valve
shaft and seating surfaces
Replace
AGun ‘spits’ paint when triggering on
due to paint build-up inside air cap
between spraying operations
Fluid tip not fitted correctly in gun head
Fluid tip/needle leakage
Tighten to correct torque
Check for damage or blockage
B
Slow fluid leak from fluid tip and
needle seat Fluid Tip internal seat scored, damaged or worn
Fluid needle external profile damaged or
worn
Contamination on needle or tip mating
surfaces preventing good seal
Incorrect fluid tip for fluid needle fitted to
gun
Sluggish needle
Tight packing nut
Replace
Replace
Thoroughly clean
Check tip/needle selection chart and fit
correct item
Lubricate packing
Adjust
B
Major fluid leak or fluid jetting from
fluid tip and needle seat Contamination on needle or tip mating surfaces preventing good seal
Incorrect fluid tip for fluid needle fitted to
gun
Fluid needle stuck or ‘binding up’
Remove tip and needle and thoroughly
clean
Check tip/needle selection chart and fit
correct item
Remove and clean fluid needle shaft, or
lubricate needle packing or loosen needle
packing

MAINTENANCE & TROUBLESHOOTING PAGE 6
MAINTENANCE & TROUBLESHOOTING PAGE 6
GUN FAULTS
Condition Cause Correction
BPaint build-up on fluid tip Fluid tip not fitted correctly in gun head
Fluid tip/needle leakage
Tighten to correct torque
Check for damage or blockage
BPaint build-up on Air cap Damaged air cap holes
Gradual build-up of bounce-back on gun
head
Replace with new Air cap
Thorougly clean
CSlow fluid leak from needle packing Fluid needle packing worn or loose Tighten or replace as necessary
DAir valve sluggish or slow to turn
on/off when trigger is
pulled/released
Air valve stem bent
Contamination on air valve stem
Replace damaged component
Remove and clean
DAir leak from around air valve stem Air valve seal damaged or missing Replace
DAir valve will not operate (air valve
stem will not fully slide into valve
body) when trigger is pulled
Air valve stem bent
Contamination on air valve stem
Remove air valve and replace damaged air
valve stem
Remove air valve and thoroughly clean
E
Stiff trigger action Air valve stem bent
Contamination on air valve stem
Contamination on trigger bearing screw
Contamination on fluid needle shaft
Fluid needle packing too tight
Replace damaged component
Remove and clean
Remove and clean
Remove and clean
Loosen packing nut
FAir leak from fluid needle exit point
in top of handle Seal damaged or missing Replace
GAir cap retaining ring will not rotate Contamination on retaining threads
Deformed or damaged retaining ring
Soak gun head in solvent to soften paint
Cut retaining ring off of gun (probably
replace retaining ring and baffle)
HUnable to turn fan control knob on
top rear of gun Internal O ring swollen or broken
Paint contamination on threads
Replace O ring
Remove and thoroughly clean
H
Unable to get round spray Fluid tip or air baffle incorrectly fitted
Air baffle chinmey damaged
Remove, check components for damage
and refit correctly
Replace air baffle
IAir leak from baffle seal Baffle seal swollen or damaged Replace
JUnable to turn air control valve on
handle of gun Internal O ring swollen or broken
Paint contamination on threads
Replace O ring
Remove and thoroughly clean

MAINTENANCE & TROUBLESHOOTING PAGE 7
MAINTENANCE & TROUBLESHOOTING PAGE 7
Spray Gun Cleaning
Suction Feed Clean Up:
Turn off air supply. Disconnect cup from lid. Raise tube out of
material and pull trigger to allow remaining material to drain
back into the cup. Then empty the cup of material. Clean the
cup, lid and tube. Add some thinner to cup.
Reassemble - Turn on air supply and spray with proper
cleaning solvent. Repeat with clean solvent if necessary.
Remove solvent, disconnect gun, remove air cap and clean.
Wipe gun and cup with cleaning solvent dampened rag.
Pressure Feed Clean Up:
First, turn off air supply to material source (cup, tank or pump).
Release material pressure from the system by opening relief
valve or pulling trigger on gun.
On a pressure cup or tank, material in hoses may be drained
back. Lid must be loose and all air pressure off. Keep gun
higher than container and pull trigger. Allow material to drain
back into the container. Pour off remaining material.
A hose cleaner can be used to clean inside of fluid hose, gun
and fluid tube in cup or tank. Connect fluid hose to hose
cleaner,. Open air valve at hose cleaner. Pull trigger on gun and
slowly open cleaning solvent valve on hose cleaner. Flush until
clean. Shut off mixing valve when solvent and air discharge is
clear. Allow air to dry passages and then shut air valve at hose
cleaner. Repeat with hose to cup or tank connected to hose
cleaner. Lid on cup or tank should be set to one side of the shell
or on a waste container.
Note - This cannot be done with a pump. Pump must be run
with proper solvent to clean.
Clean inside of container and lid. Wipe down gun with cleaning
solvent dampened rag, then lubricate. Use SSL-10 spray gun
lube.
Without a hose cleaner, remove excess material from cup or
tank and clean. Set up cup, tank or pump to operate with clean
cleaning solvent. Turn off atomisation air to gun. Trigger gun
into waste container. Continue flushing until cleaning solvent is
clear. Blow air through hose to dry. Wipe hose and gun with
cleaning solvent dampened rag and lubricate gun.
Cleaning the Air Cap:
Remove the air cap and, if dirtied with dry paint, let it soak in
clean solvent. Later, brush and wipe off the air cap. If any holes
in the cap are clogged, probe them with a whittled match-stick
or tooth pick. Don’t ream the air cap holes with wire, nails or
metal tools. This may damage the hole and result in imperfect
spray patterns.
Note - Never soak the entire gun in cleaning solvent. This will
dry out the packing and remove lubrication.
Lubrication:
Daily, or after each use if intermittent, place a drop of SSL-10
gun lube on the points shown. Springs behind the fluid needle
and air valve should have a light coat of petroleum jelly.

MAINTENANCE & TROUBLESHOOTING PAGE 8
MAINTENANCE & TROUBLESHOOTING PAGE 8
JGA Spray Gun Maintenance Schedule
A. Every Shift
1) Check front air cap face and all air cap holes are free from damage. Replace if necessary
2) Check fluid tip external profile is undamaged. Replace if necessary
4) Check fluid needle is seating correctly in fluid head allowing no seepage. Replace or lap-in if necessary.
5) Turn off pressure tank fluid cock and/or compressed air supply to gun. Trigger gun. Apply one drop of spray gun lubricant to
needle shaft immediately behind fluid needle packing screw. Release trigger. Repeatedly pull and release trigger to work
lubricant into fluid needle packing.
6) Check trigger operates smoothly and fluid needle does not stick or bind up during movement due to damage or paint build-up.
7) Apply single drop of lubricant to each side of trigger pivot screw. Repeatedly pull and release trigger to work lubricant into
trigger pivot.
8) Apply single drop of lubricant to air valve stem. Repeatedly pull and release trigger to work lubricant into air valve packing
seal.
9) Check air valve operates smoothly without sticking. Replace valve stem if necessary.
10) Check needle packing for fluid leakage. If required, tighten the needle packing by rotating packing screw until the needle
starts to bind, then loosen the packing nut just enough so that the needle moves freely. If screw bottoms without eliminating
fluid leak, replace packing with new item.
B. Additional end of week maintenance checks
1) Check air cap retaining ring and gun air baffle threads are free from damage (a smear of Vaseline on the threads will help
prevent binding).
2) Check air baffle seal is not leaking air badly or visibly damaged. Replace if necessary.
3) Apply smear of Vaseline to needle shaft front end for smooth operation.
4) Apply Vaseline to needle shaft rear end and needle spring to aid corrosion and contamination resistance.
5) Check Horn control valve is free to rotate with no stiff spots. Lubricate or replace O ring if necessary.
6) Check Air control valve, if fitted, is free to rotate with no stiff spots. Lubricate or replace O ring if necessary.
7) Check for air leaks from aircap when gun is not triggered. Clean or replace air valve stem or seat if necessary.
8) Check Trigger retaining screw is tight.
9) Check fluid and air inlet connectors are tight and sealed. Tighten if necessary.
C. Additional Bi-weekly maintenance checks
1) Check for air leakage from air valve body when trigger is pulled. Replace air valve seal if necessary.
2) Check fluid needle shaft is not badly worn and needle end profile and point are undamaged.
3) Apply a smear of Vaseline to all air O rings to aid fitting and easy rotation.
4) Check gun body for damage, particularly around air inlet connector port.
5) Check stainless steel head fluid insert, if fitted, for damage to fluid tip seat, swaging or leaks caused by rotation. This item is
not removable or replaceable, and a new gun body will be necessary.
6) Check for damage to air baffle chimney. Replace air baffle assembly if necessary.
7. Apply Vaseline to air valve spring to aid corrosion and contamination resistance.
ITW DeVilbiss
Ringwood Road
Bournemouth
BH11 9LH
Tel: [phone]
Steve Mannouch Oct96