TM 43-0139
Table 5-1. Drop In Air Pressure
Air pressure drop at spray gun (psi)
Air pressure at
transformer
5-foot
10-foot
15-foot
20-foot
25-foot
50-foot
(psi)
length
length
length
length
length
length
air hose = 1/4 inch diameter
40
6
8
9 1/2
11
12 3/4
24
50
7 1/2
10
12
14
16
28
60
9
12 1/2
14 1/2
16 3/4
19
31
70
10 3/4
14 1/2
17
19 1/2
22 1/2
34
80
12 1/4
16 12
19 1/2
22 1/2
25 1/2
37
90
14
18 34
22
25 1/4
29
39 1/2
air hose = 5/16 inch diameter
40
2 1/4
2 3/4
3 1/4
3 1/2
4
8 1/2
50
3
3 1/2
4
4 1/2
5
10
60
3 3/4
4 1/2
5
5 1/2
6
11 1/2
70
4 1/2
5 1/4
6
6 3/4
7 1/4
13
80
5 1/2
6 1/4
7
8
8 3/4
14 1/2
90
6 1/2
7 1/2
8 1/2
9 1/2
9 1/2
16
d.
Valves and Gages.
(1)
Valves and gages used on spray painting equipment are of rugged construction and normally will need little
attention to insure their correct operation. The following suggestions may be helpful in maintaining this equipment in good
condition:
(2)
Keep valves free from paint by wiping with a cloth dipped in solvent or thinner. Do not immerse valves in
solvents or thinners, as this will dry out the packing.
(3)
Be sure that valve nipples are of the correct size for the inside diameter of the hose being used. Incorrect
mating of hose and nipple is a common cause of spray gun malfunction.
(4)
Do not repair air gages in the field. Have this done by experienced and qualified personnel using the
special tools and skills required for their proper adjustment.
e.
Air Transformers.
(1)
General. An air transformer, or separator, is a device which condenses oil and moisture, regulates and
filters the air, and provides outlets to which spray guns and dusters may be connected (see figure 5-13).
(2)
Operation.
(a)
Oil and moisture are collected by the baffles and filter pack, allowing only clean, dry air to reach the
spray gun. Further drying may be accomplished by the use of cartridges filled with a desiccant, such as silica gel, and
installed in the outlets.
(b)
Oil and moisture collect at the bottom of the air separator or transformer and should be removed daily
(see figure 5-14).
(3)
installation. Proper installation of the air transformer is essential to maintain correct operation. The
following points are to be observed:
5-20
