gun air valve daily with light oil. Keep all spray-gun packings, such as the fluid needle packing, soft
and pliant by occasional applying oil.
3-10. Hoses. There are two types of hoses-air and fluid:
a. Air. Air hoses are generally lightweight, flexible, kink-free, and will withstand pressures as
recommended by the manufacturer. For proper spray-gun equipment operation, the gun must receive an
adequate supply of compressed air. Ensure that the required amount of air is applied by using air hoses
of the proper size.
b. Fluid. Fluid hoses are usually made of synthetic rubber and are used with all types of
painting materials, solvents, and oils. Fluid hoses are cleaned at the same time as the gun when thinner
or solvent is forced through them by air pressure.
3-11. Air Compressors.
a. Air compressors are mechanical units designed to continuously supply compressed air at a
specific pressure and volume. Compressors have an electric motor or a gasoline engine. The Army
painter is primarily concerned with two types of air compressors-low pressure and high pressure.
(1) Low Pressure. The low-pressure air compressor shown in Figure 3-41, weighs
approximately 50 pounds. The overall weight of this unit includes the air-pressure pump, the air-
pressure tank, and the driving unit. Since the spray unit is designed to operate on pressures from 20 to
40 pounds per square inch, you should exercise caution against applying higher pressures. Because this
gun operates at low pressures, it is not recommended for spraying quick-drying paints, lacquers, or
Figure 3-41. Low-pressure air compressor (electric motor)
(2) High Pressure. Use this compressor for large jobs where heavy-duty spray equipment is
required. A high-pressure air compressor is shown in Figure 3-42, page 3-34.