OPERATING INSTRUCTIONS
Model No. 331 -A Spray Gun
This gun was thoroughly tested and was found to op-
erate perfectly before leaving the factory.
TYPE OF GUN
This spray gun serves three specific and different
painting functions. First as .an "External Mix,"
"Pressure Feed" type it renders fast application of
latex paints. Second as an "Internal Mix," "Pres-
sure Feed" type it delivers maximum efficiency in
the spraying of oil based paints. Third as an "Ex-
ternal Mix, ""Syphon Feed" type it gives extremely
fine atomization for smooth finishes with fast dry-
ing lacquers and enamels.
HOW TO USE
EXTERNAL MIX PRESSURE FEED -Attach the die
cast nozzle with side vents to the gun. Make sure
that the socket head set screw is in place in the cup
cover, (gun is shipped from factory in this manner).
INTERNAL MIX PRESSURE FEED -To convert
from external mix pressure feed to internal mix
pressure feed, simply replace die cast external
mix nozzle with steel internal mix nozzle. Internal
mix fan nozzle is furnished with the gun. Round and
angle nozzles are available on special order.
EXTERNAL MIX SYPHON FEED -To convert this
gun to external mix syphon feed, remove the air
nozzle and liquid nozzle from the gun. Use the small
hex wrench furnished with the gun to remove the
small socket head screw from the cup cover. Screw
this socket head screw into the small threaded open-
ing on the face of the gun where the liquid nozzle
was removed. Replace the liquid nozzle and attach
die cast external mix nozzle. Do not attempt to use
internal mix nozzles when gun is assembled for
syphon feed spraying.
"BLEEDER" or "NON-BLEEDER." This spray gun
has abuilt in air valve that can be changed for
bleeder or non -bleeder operation. When shipped
for use with portable air compressors having no air
storage tank the spray gun is always assembled for
"BLEEDER" operation, which means the air will
pass continuously through the nozzle when trigger is
released as well as when spraying. To change this
gun to a"NON-BLEEDER" type, remove lower pack-
ing screw at upper rear of gun. Remove spring and
small air valve screw, and slip air valve washer
over threads of air valve screw. Reassemble gun.
The spray gun is assembled at the factory with the
lower end of the liquid" tube facing forward toward
the nozzle end of the gun. This position is most
satisfactory for floors and vertical surfaces. For
ceilings screw in pipe one half turn so that lower
end of liquid pipe faces rear or handle end of gun.
Before spraying, the aluminum cup should be screwed
against the gasket tight enough to prevent excessive
air leakage at th:s point. Aslight amount of air leak-
age at this point will not prevent the gun from spray-
ing properly, but care must be taken not to nick the
top of the cup or to use defective gaskets which will
permit alarge air leakage, or the gun will not spray
satisfactorily.
If leakage of paint occurs through packing gland nut
around the needle pin, tighten the packing gland nut
just tight enough so that the needle will still move
freely. An occasional drop of light machine oil on
packing leather will keep it soft and help prevent
leakage.
TWO SPRAYING ADJUSTMENTS PROVIDED
The air adjusting screw is the upper of the two
knurled knobs at the rear of the gun. This controls
the amount of air supplied to the spray nozzle.
The trigger stop screw is the lower of the two
knurled knobs. This- adjusts the amount of trigger
movement which controls the amount of needle valve
opening regulating the flow of paint.
^For most spraying application the two adjusting
knobs should be in the open position to allow for
maximum air delivery and trigger opening. Differ-
ent adjustments of the positions of these adjusting
knobs will produce awide range of spraying results.
SAFE WORKING AIR PRESSURES
This spray gun is designedto operate most efficient-
ly at air pressures between 30 and 50 pounds. In no
case should more than 50 lbs. pressure be used on
this gun.
HARDENED STEEL NEEDLE AND NOZZLES
The needle pin, liquid nozzle and internal mix air
nozzles are all precision made of steel and hardened
to resist the cutting action of abrasives found in
many paints
.
USING 2V2 GALLON PRESSURE PAINT TANK
For paint tank operation remove the socket head
screw from the cupcover and screw into the face of
the gun by the liquid nozzle, the same as for exter-
nal mix syphon feed operation. Then remove quart
cup, liquid tube, cup cover casting and sleeve nut
and attach paint hose at this point.
DIRECTIONS FOR SPRAYING
1.Thoroughly mix the material, adding thinners as
indicated on label. Most materials in common use
will spray readily if thinned according to the manu-
facturer's instructions for brushing. However, if
material still appears too thick, add alittle more
thinner, determining the amount by testing mixture
in gun. Be sure the material you use for spraying
is clean, and free from lumps. Strain it through
cheese cloth, regular paint strainer or apiece of
common screen wire.
