DeVilbiss GTI-500P Service Bulletin

GTI-500P and GTI-520P COMPLIANT PRESSURE FEED HVLP SPRAY GUNS
IMPORTANT: Before using this equipment,
read all safety precautions and instructions.
Keep for future use.
DESCRIPTION
These pressure feed high volume low pres-
sure GTI guns are designed to apply a wide
variety of finishing materials. These guns
are manufactured to provide maximum
transfer efficiency by limiting air cap pres-
sure to 10 psi (complies with rules issued by
SCAQMD and other air quality authorities).
These guns will produce approximately 10
psi cap pressure at 30 psi gun inlet pres-
sure. Air cap test kits are available (see
ACCESSORIES) which can be utilized to set
the exact air cap pressure. Air consumption
for the GTI-500P (#100 cap) is 16 SCFM
at 10 psi air cap pressure. Air consumption
for the GTI-520P (#2000 cap) is 15.5 SCFM
at 10 psi air cap pressure.
NOTE
These guns include 400 series
stainless steel fluid tips and
needles. Guns may be used with
chlorinated solvent materials. See
page 2 for additional warnings.
Important: These guns may be used with
most common coating and finishing mate-
rials. They are designed for use with mildly
corrosive and non-abrasive materials. If
used with other high corrosive or abrasive
materials, it must be expected that fre-
quent and thorough cleaning will be re-
quired and the necessity for replacement of
parts will be increased.
INSTALLATION
For maximum transfer efficiency, do not
use more pressure than is necessary to
atomize the material being applied.
1 . Connect the gun to a clean, moisture
and oil free air supply using a hose size
of at least 5/16" I.D. hose. Do not use
1/4" I.D. hose (25' x 1/4" hose at 18 CFM
has a pressure loss of 25 psi. 25' x 5/16"
hose at 18 CFM has a pressure loss of
8 psi).
NOTE
Depending on hose length, larger I.D.
hose may be required. Install an
HAV-501 air gauge at the gun handle
and air cap test kit over tip. When
gun is triggered on, adjust regulated
pressure to desired setting to provide
a maximum of 10 psi at the air cap.
Do not use more pressure than is
necessary to atomize the material
being applied. Excess pressure will
create additional overspray and re-
duce transfer efficiency.
NOTE
If quick connects are required, use
only high flow quick connects ap-
proved for HVLP use such as DeVil-
biss HC-4419 and HC-4719. Other
types will not flow enough air for
proper gun operation.
NOTE
If an air adjusting valve is used at the
gun inlet, use DeVilbiss Model HAV-
500 or HAV-501. Some competitive
adjusting valves have significant
pressure drop that can adversely
affect spray performance. Models
HAV-500 and HAV-501 have minimal
pressure drop, which is important for
HVLP spraying.
2 . Attach the fluid hose to the material
inlet.
NOTE
Protective coating and rust inhibi-
tors have been used to keep the
gun in good condition prior to ship-
ment. Before using the gun, flush it
with solvents so that these materi-
als will be removed from fluid pas-
sages.
OPERATION
Mix, prepare and strain the material to be
sprayed according to the paint maufacturer's
instructions.
Strain material through a 60 or 90 mesh
screen.
1 . Fill the pressure tank with the mate-
rial.
2. Open the spreader adjustment valve
(10) (Fan) by turning the valve stem
counterclockwise.
3. Open fluid adjusting screw (17) by turn-
ing counterclockwise.
4 . Turn on air supply to gun and pressure
tank and set gun inlet pressure to
lowest recommended pressure for ma-
terial being sprayed. Spray a test area.
Air pressure and paint flow should be
adjusted to provide a uniform disper-
sion of atomized paint throughout the
pattern. Due to the unique cone shape
of the AV-2120 fluid tip, a slight back
pressure is created against the fluid
column. This will reduce the amount
of fluid output. To compensate, in-
crease the fluid regulator pressure
SERVICE BULLETIN
SB-2-193-G
Replaces SB-2-193-F
Repair Kit KK-5058-2
slightly. With 10 psi cap pressure, back
pressure is approximately 2.0 psi. Keep
air pressure as low as possible to mini-
mize bounce-back and overspray. Ex-
cessive fluid flow will result in heavy
center spray patterns. Inadequate flows
may cause the patterrn to split. See
TROUBLESHOOTING, Page 5, if any
problems occur. If finer atomization is
required, increase gun inlet pressure.
If a reduced fluid flow rate is required,
turn fluid adjusting screw (17) clock-
wise until desired fluid flow is obtained.
See Spray Gun Guide, SB-2-001 latest
revision, for details concerning setup of
spray guns.
PREVENTIVE MAINTENANCE
To clean air cap and fluid tip, brush exterior
with a stiff bristle brush. If necessary to
clean cap holes, use a broom straw or
toothpick if possible. If a wire or hard instru-
ment is used, extreme care must be used to
prevent scratching or burring of the holes
which will cauase a distorted spray pattern.
To clean fluid passages, remove excess
material from cup, then flush with a suitable
solvent. Wipe gun exterior with a solvent
dampened cloth. Never completely immerse
in solvent as this is detrimental to the lubri-
cants and packings.
NOTE
When replacing the fluid tip or fluid
needle, replace both at the same
time. Using worn parts can cause
fluid leakage. See Chart 2. Also,
replace the needle packing at this
time. Lightly lubricate the threads
of the fluid tip before reassem-
bling. Torque to 12-15 ft. lbs. Do
not overtighten the fluid tip.
To prevent damage to fluid tip (5)
or fluid needle (11), be sure to
either 1) pull the trigger and hold
while tightening or loosening the
fluid tip, or 2) remove fluid needle
adjusting screw (17) to relieve
spring pressure against needle
collar.