Fluid Delivery
Options
Spray Application Processes
Atomization Technology Options
Gun
Air
Conventional, HVLP, LVMP, Air Assisted Airless and Airless are all types of
Air
Atomization technology, each has slightly different operating parameters.
Pressure Tank
Fluid
Pressure-Feed
Conventional
This option uses an external
pressure source (pressure tank,
piston pump, or diaphragm pump)
to push fluid to the spray gun
nozzle. Air and fluid are then
mixed outside the nozzle to
atomize the coating.
Advantages: This method delivers
higher volumes of fluids than
siphon and gravity-feed set-ups,
and will spray a wider range
of materials. It also enables
independent control of fluid and
air pressure.
The most established method of air atomizing, used on spray guns for decades.
This type uses high velocity air jets to produce a high atomization power
which is very effective in breaking up high solids and high viscosity coatings.
Air pressure exiting the air cap during use is typically 40-70 psi (2 to 5 bar) with
typical air consumption of 6 to 25 cfm (170 to 700 l/min).
High Volume Low Pressure (HVLP)
HVLP uses higher volumes of air (11 to 30 cfm or 300 to 840 l/min) at low
pressure (psi) to atomize the coating. HVLP provides high transfer efficiency
and is limited by Government Environmental Legislation to a maximum of
Extractor
10 psi (0.7 bar) atomizing pressure measured at the air cap.
Gravity Cup
with Fluid
Low Volume Medium Pressure (LVMP)
Air Supply
LVMP makes more energy available for the atomization process than HVLP,
Gravity-Feed
but delivers transfer efficiencies equivalent to those of HVLP. Air cap pressure
On Gravity-feed guns the cup is
located above the gun. The force
of gravity pushes the fluid
into the gun.
Advantages: This method
offers quick color changes and
convenience on small jobs or
touch up applications. Gravity
guns are able to use all of the
coating – reducing waste.
is typically in the area of 20 to 45 psi (1.3 to 3 bar) while using 9 to 20 cfm
(250 to 560 l/min) for atomization of coatings.
Air Assisted Airless
To maximize efficiency, the best features of air spray and airless atomization are
combined in this technology. The pattern is formed by the spray tip at between
500 and 2,500 psi fluid pressure and a small amount of air pressure is used to adjust
the size of the spray pattern and eliminate “tails”. Air Assisted Airless provides fast
Clean
Air Filter
application of materials, a soft spray that reduces fog overspray and bounce-back,
Gun
and the ability to penetrate into recesses and cavities. This is especially important
where intricate shapes require a consistent film build.
Air
Siphon Cup
Airless
Siphon-Feed
Siphon-feed hookups use vacuum
created at the nozzle to draw fluid
from a cup.
Advantages: This fluid cup
system offers quick material /
color changes, easy clean-up on
smaller jobs.
Fluid is atomized by high pressure (usually 3,000 – 7,000 psi) and pushed through an
orifice in the spray tip which is typically .015" - .035" in diameter. The shape of the
orifice determines the shape and size of the spray pattern. Wi th airless technology,
the size of the atomized particle is larger than other spray methods and therefore
typically not used for achieving fine finishes.
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Protective Coatings Equipment Selection Guide