Technical data

4.3.5 Air Compressors. Air compressors provide a
continuous supply of compressed air at a predetermined
maximum pressure and a minimum volume in cubic feet per
minute. There are two general types of air compressors,
single stage and two stage. These can be further subdivided
into many types such as portable or stationary, electric motor
or gas engine driven, unloader or pressure switch controlled,
and air or water cooled.
4.3.6 Air Regulators or Transformers. A regulator is a
device equipped with indicator gages which reduces the main
line air pressure to a lower regulated pressure. It also provides
outlets to which spray guns and other air operated equipment
may be connected. It must be capable of providing 15 cfm of
air at 80 PSI (supply line pressure) with a maximum pressure
drop of 10 PSI.
4.3.7 Air Condensers. An air condenser is similar to
the air transformer and separates oil and moisture from the
air. A condenser is usually equipped with pressure gages, but
may be found without gages where a regulated supply of air
is available.
NOTE
Air condensers and transformers shall be drained
at least daily and more frequently in humid
weather.
4.3.8 Air Supply. Figure 4-6 illustrates proper installa-
tion of an air supply for paint spraying.
4.3.9 Hose.
Hoses shall always be thoroughly cleaned by
flushing with solvent appropriate for the coating
material used. When the material is a catalyzed
(two component) system (epoxy or polyure-
thane), this must be done immediately after use to
prevent the material from curing in the hose.
Because of friction losses in hose, it is essential that the
proper size and length be used. Do not use hoses longer than
50 feet. High-pressure air hose leading from the air source to
the regulator or tank which may be a maximum of 150 feet if
required to reach the tail surfaces of exceptionally large
aircraft. Extra lengths of hose may be attached for this use but
shall be removed as soon as no longer needed. The high-
pressure air hose shall have a minimum inside diameter (ID)
of 7/16 inch. The fluid hose from the tank to the gun shall be
no less than 3/8 inch ID and the air hose from the regulator to
the tank and from the tank to the gun shall be no less than
5/16 inch ID. Any reduction in size or increase in length may
produce unsatisfactory results. Air and paint hoses are fur-
nished in various standard lengths.
4.4 SPRAY PAINTING.
4.4.1 Gun Techniques. Spray guns are designed to be
used with certain spraying techniques. The quality of finish
that is applied will depend on how well these techniques are
used by the painter. Spraying techniques include the follow-
ing:
Figure 4-3. Airless Spray System
TO 1-1-8
4-5