TM 5-4310-393-14
Section III. TECHNICAL PRINCIPLES OF OPERATION
Paragraph
Page
1-12
Compressor ............................................................................................................ 1-9
1-13
Pneumatic Air Flow ................................................................................................. 1-9
1-14
Purifiers .................................................................................................................. 1-9
1-12. COMPRESSOR.
The compressor is driven at a speed of 1300 rpm. When a pressure of 3200 psi is reached in the vessel being filled, the
safety relief valve on the fill hose assembly will open to atmosphere. The first stage of the compressor block is connected
to the second stage with a tube that serves as an intercooler. The purpose of the intercooler is to reduce the interstage
temperature of the air, increasing the unit volume and ultimately the volumetric capacity for the entire multi-stage
reciprocating compressor.
The second stage discharge is passed through another intercooler to an oil/water separator, and then to the inlet of the
third stage The third stage discharges to an aftercooler tube which is connected to a final oil/water separator. From the
final oil/water separator, the air is tubed to a final purification cartridge and then through a pressure maintaining valve to a
service port.
Manual condensate drain valves are provided at each of the two oil/water separators. These separators should be
drained every 15 to 20 minutes during operation of the compressor, and after the unit is shutdown for the day.
1-13. PNEUMATIC AIR FLOW.
Refer to Figure 1-3 Compressed Air Pneumatic Flow Diagram. The 1st stage draws in atmospheric air through an intake
prefilter (1) The air then goes through the intake hose (2), and through a 10 micron intake air cleaner filter (3). The air Is
drawn into the first stage cylinder (4) and is compressed to 56 psi (4 bar). The pressurized air is cooled between the first
and second stages by an Intercooler (5). In the second stage cylinder, air is compressed to 500 psi (35 bar) and then
passes through a second Intercooler (7) and enters an oil/water separator (8). From the oil/water separator (8) the air
enters the third stage cylinder (9), where it is compressed to 3200 psi (221 bar), the operating pressure of the unit. The
air is cooled again by passing through an aftercooler tube (10) and most remaining oil/water is removed by the final
oil/water separator (11). The air is then cleaned by the purification cylinder (13). Air leaving the purification cylinder goes
through a pressure maintaining valve. A fill hose assembly is provided between the pressure maintaining valve and the
service air outlet (20). Air pressures are safety maintained by safety relief valves at each compressor stage and by a
safety relief valve placed in the fill hose assembly. Check valves (12) are Installed on each side of the purification cylinder
to prevent back flow of air into the system from a service air cylinder which might be above system pressure or
contaminated Manually operated drain valves (15 and 16) are installed for each oil/water separator (8 and 11). The
purification purge valve (17) will depressurize the system when opened.
1-14. PURIFIERS
The compressed air is rendered free from most of the heavy oil and water by an oil/water separator between the second
and third stage, and by an oil/water separator after the third stage. Final purification of the air is accomplished by the
purification cylinder located after the final oil/water separator. The purification cylinder contains a dryer/purifier cartridge
which removes all residual oil and water vapors, providing treated air, free of oil, taste, and odor for respiratory use by
divers
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