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Choosing a
System |
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INTRODUCTION |
In
general, all spray systems perform the same tasks, therefore the type of
system to choose depends on what, how much and how fast you plan on
spraying. Every set-up has three essential components: a gun which sprays
the finish, a cup or pot which hold the finish and a power system (air
compressor) which moves the finish through the gun and atomises it at the
tip. |
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SPRAY
GUN |
Regardless of the variety and
sizes of spray gun, they are basically the same – they contain inlets for
air and fluid, fluid needles and tips and an air cap (see
how it works). The airline/hose from the air compressor
attaches to the gun and fluid enters the gun from a pot/cup mounted directly
to the gun. Screws located on the back of the gun can adjust the fluid and
air flow. There are two major types of spray gun: suction-feed and
gravity-feed.
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SUCTION FED SPRAY GUNS
There are
several ways to identify this type of gun quickly. The material container
or pot is located below the gun, the lid to the container will have vent
holes and the fluid tip extends just beyond the face of the air cap.
Spraying is achieved by compressed air entering the gun and moving through
it to create a vacuum at the air cap. Outside air is allowed to enter
through vent holes on the pot lid. The difference in air pressure produces
a siphon that draws material up the fluid tube and into the gun. The
material is drawn through the fluid tip where it mixes with the air coming
from the cap and is atomised
(see
how it works). |
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GRAVITY FED SPRAY GUNS
These guns
can be easily identifiable by the material cup, which is located at the top
of the gun. The force of gravity allows the material to flow down into the
gun, eliminating the need for a fluid tube. Like suction-feed guns vent
holes allow air to pass through the top of the cap ensuring constant flow of
material. Since no atomising air is required to move material, gravity guns
are more efficient than suction-feed and also require less compressed air.
Suction-feed guns are ideal for small to medium projects and can be used in
many different positions such as overhead spraying. Gravity-feed guns are
lighter and give better balance, which takes the strain of the operator’s
wrists. |
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Reciprocating air compressors basically compress atmospheric air to a given
capacity and pressure. The type of unit will depend on the spray gun
selected and the number of guns to be used at any one time. For the
hobbyist a complete spray system can be purchased including the spray gun,
hose complete with connectors and the air compressor. Guns that are
purchased separately will display the average air consumption in CFM (cubic
feet per minute) and pressure in either Bar or PSI (pounds per square
inch). A compressor can then be purchased ensuring the FAD (free air
delivery) of the unit and the pressure is equal to or more than the air
consumption of the gun.
Lubrication free compressors are better for paint spraying as there will be
no contamination of the paint while spraying.
(understanding your compressor) |
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To connect the Spray Gun to the
compressor you will need a selection of couplings, fitting and high pressure
hose, quick release couplings should also be used, these allow the hose or
gun to be disconnected safely without any loss of air from the system. |
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USE YOUR SPRAY GUN FOR: TIME SAVING – VERSATILITY – QUALITY FINISH – EASE OF
LEARNING - |
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