Section 2
DESCRIPTION
12
Stop compressor and relieve all internal pressure
before doing so.
2.6 CAPACITY CONTROL SYSTEM, FUNCTIONAL
DESCRIPTION
Refer to Figures 2-3, 2-4A, 2-4B or 2-4C. The pur-
pose of the control system is to regulate the amount
of air intake in accordance with the amount of com-
pressed air being used. The control system con-
sists of a pressure regulating valve(s), air inlet
valve, system blowdown valve, and tubing con-
necting the various components to the compressor
and engine governor. The functional descriptions of
the control system are given in four distinct phases
of operation. It applies to any control system with
the exception of those with stated pressures which
are dependent on pressure requirements. The pres-
sures stated will be in accordance with a compres-
sor having an operating pressure range of 100 to
110 psig (6.9 to 7.6 bar).
START - 0 TO 40 PSIG (0 to 2.8 BAR)
COLD WEATHER
To minimize problems in cold weather, starting aids,
engine coolant heaters and dry-side receiver relief
valves should be used. Refer to the engine opera-
tors manual for additional information.
COLD START
When the compressor is started, the sump pressure
will quickly rise from 0 to 40 psig (0 to 2.8 bar).
During this period the pressure regulator valve is
inactive. At this pressure range the idle warm-up
control maintains a closed inlet valve for engine idle
operation. After engine start-up, turn the handle of
the selector valve warm-up control (located on the
instrument panel) from the “start” to the “run” posi-
tion within the first 30 seconds of operation. The
instrument panel annunciator light will go off after
30 seconds. The inlet valve is fully open due to inlet
air pressure, and the compressor operates at full
capacity operation. As the compressor operates at
full capacity, the engine runs at full speed.
NORMAL OPERATION - 85 TO 100 PSIG (5.9 TO
6.9 BAR) OR 85 TO 150 PSIG (5.9 TO 10.3 BAR)
FOR “H” MACHINES
When the warm-up control selector valve handle is
moved to the “run” position, the sump pressure
rises above 85 psig (5.9 bar). At this time, the inlet
valve remains fully open for maximum air output.
The engine will continue to run at full speed during
this phase of operation.
Figure 2-3 Compressor Discharge System
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