TM 5-4310-386-14
1-10. Safety, Care, and Handling. The following are general safety rules and precautions that should be followed when
operating the K-20-D Compressor Unit.
a. Always ensure that the intake air is absolutely pure and free of exhaust fumes.
b. Always use air intake hose. This will help preclude intake of exhaust fumes.
c. Filling hoses must be in satisfactory condition and threads undamaged. Pay particular attention to damage at
hose connections. If the rubber is scored, hose must be discarded, otherwise water can enter and attack wire gauze
causing it to rust, thus endangering pressure tightness.
d. Never open filling valves when under pressure and not connected. Highly compressed air emerging can cause
serious accidents.
e. Check for leakage of the complete system from time to time by brushing all fittings and couplings with soapy
water. Repair any leakage.
f. Always shut down and bleed air from the system prior to carrying out any work on the compressor.
g. Always disconnect the system from the battery prior to carrying out any work on compressor unit.
h. Never reweld pressure lines.
Section III. PRINCIPLES OF OPERATION
Paragraph
Page
1-11
General......................................................................................................................................
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1-12
Pneumatic System .....................................................................................................................
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1-11. General. (Figure 1-3) The K-20-D Compressor Unit consists of a high pressure compressor coupled by a V-belt
drive to a two cylinder diesel engine.
1-12. Pneumatic System. The four stage compressor is connected by a matched set of drive belt/s to the engine. The
compressor is air cooled with inter-stage coolers, an after cooler, oil and moisture separators and an axial cooling fan.
The compressor will deliver 20 cfm of diving air at 3200 psi (22064 kPa). When the relief valve closes at that pressure,
the compressor begins delivering compressed air to the service outlet.
a. When the clutch is engaged, the compressor operates as follows: The first stage of the compressor draws in
atmospheric air through the micronic intake filter (1). Here the air is compressed to a pressure of approximately 44 psi
(303.38 kPa). The compressed air entering the second stage is cooled by inter-cooler (2). In the second stage the air is
further compressed to approximate 210 psi (1447.95 kPa), and then passes through inter-cooler (3) and inter-filter (6) to
the third stage. In the third stage the air is a compressed to 1015 to 1088 psi (6998.42 to 7501.76 kPa). Leaving the
third stage the air passes through inter-cooler (4) and inter-filter (7) to the fourth stage. In the fourth stage the air is finally
compressed to 3200 psi (22064 kPa). On leaving the fourth stage the air is passed through after-cooler (5) and routed
through the oil and water separator (11). The intermediate pressures of the individual stages are monitored by the
intermediate pressure safety valves (8), (9), and (10). Final pressure is monitored by final pressure safety valve in the
purification system.
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