TM 5-4310-387-14
(11) After the engine speed stabilizes at about 3200 RPM, close separator drain valves (1) and (2). Air
pressure will then begin to rise in each compressor stage.
NOTE
During initial start-up, a knocking sound will be generated by the floating piston
in the third stage. This knocking sound will continue for several seconds until
the air pressure in the third stage is high enough to hold the floating piston
against the third stage guide piston. This knocking sound is completely normal
and is not a cause for alarm.
(12) Check for final stage safety operating by listening for air discharging from the safety valve. Also note blow
off pressure on pressure gauges (11).
c.
Servicing SCUBA Cylinders. (figure 2-6)
(1) Review warning page as instructed in para. 1-11.
(2) Refer to FM 20-11-1 and check air purity standards.
(3) Start the air compressor (para. a.).
WARNING
SCUBA cylinders with valves that have been left open must not be charged
without first being property purged to avoid contamination.
(3) Check that the SCUBA cylinder shutoff valve (1) is closed prior to servicing.
(4) Remove the charging whip (2) from the compressor and remove the dust cap from the filler adapter (3).
(5) Orient the filler adapter (3) on the SCUBA cylinder manifold (4) and screw down the handle-screw (5)
sufficiently to create a seal.
(6) Open the filling valve (6).
(7) Place the reserve valve knob (7) in the down position and open the SCUBA tank shutoff valve (1).
NOTE
During the filling procedure the SCUBA cylinders will warm up and then cool
down after being detached from the compressor. The cylinders will then need
topping-off to the required nominal filling pressure. However, this tedious
procedure can be avoided by using a water tank for submerging the SCUBA
cylinders while filling them.
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