TM 5-3810-307-24-1-2
Discharge Air System
The air discharge line provides the route for compressed
high pressure air from the air compressor to the air stor-
age or reservoir tank system.
As a result of compressor discharge air containing a
small amount of oil mist at high temperatures, carbon
formation in the discharge line becomes a common air
system problem.
In severe instances, the problem can lead to discharge
line restrictions and shorten compressor life. To prevent
this problem, the following installation guidelines must be
followed:
Discharge Air Cooling: To provide air cooling of
discharge air, the plumbing line connected to the exhaust
port must be made of copper, steel, or wire braided
Teflon tubing capable of withstanding 1034 kPa [150
psi] pressure peaks and normal continuous line
pressures of 931 kPa [135 psi] at temperatures of 232C
[450F]. Ideally, 1.8 m [6 ft] minimum length of copper
tubing, or 3.1 m [10 ft] minimum of Teflon/stainless
steel tubing provides adequate air cooling.
NOTE
If an air dryer is used, see manufacturer's
guidelines.
Air Flow Restrictions: To minimize air flow
restriction caused by carbon formation, avoid discharge
line bends with a radius of less than 50.8 mm [2 inches].
General air flow direction must be downward from the
discharge port without traps where oil and moisture can
collect. Discharge line low spots or traps can result in
carbon formation or water freeze points which restrict air
flow.
Discharge Line Size: Discharge line sizes for the
single cylinder compressors must be 16 mm [5/8- inch] ID
or a No. 12 hose, with a minimum of 12.7 mm [1/2-inch]
ID or a No. 10 hose for optimum performance.
The twin cylinder compressor optimum line size is 19 mm
[1 inch] ID or No. 16 hose, with a minimum of 16 mm
[5/8-inch] ID or No. 12 hose.
Smaller than optimum line sizes will reduce compressor
life under high duty cycle conditions.
