Compressor Control System - AADCO 737 Series Operating Instructions Manual

8.0

COMPRESSOR CONTROL SYSTEM

(SEE FIGURE 17 FOR PNEUMATIC REFERENCE
AND FIGURE 18 FOR ELECTRICAL REFERENCE.)
8.1 A combination pressure switch/pressure relief valve system is installed in all
AADCO pure air generators with output volumes greater than 1-LPM but less
than 50-LPM.
8.2 The purpose of this system is to permit the compressor to operate intermittently
rather than continuously. The compressor will turn on at 60-psig or less and off
at 80-psig.
compressor wear and promotes cooler operation, both of which extend its
lifespan.
8.3 During operation the ballast tank, Figures 1, 2 and 9 (16), serves as the
pressure reference for the system. The pressure switch, Figures 5 and 6 (17),
serves as the sensor and the check valve, Figures 1, 2 and 9 (24), confines the
pressurized air within the ballast tank once the compressor has turned off.
8.4 The pressure switch is a normally closed switch, closing at 60-psig or less and
opening at 80-psig. This switch controls the coil of the solid state relay, Figures
5 and 6 (21), which in turn supplies power to the compressor through the AUX
POWER outlet, Figure 1.
8.5 Any low pressure condition (60-psig or less) within the ballast tank produces a
closed switch condition at the pressure switch. This in turn causes power to be
supplied to the compressor via the solid state relay, Figures 5, 6 and 11 (21),
and the AUX POWER outlet.
8.6 At 80-psig the pressure switch opens, removing power from the coil of the solid
state relay, which in turn removes power from the compressor.
8.7 The compressor pressure relief valve, Figure 8 (23), (a normally closed three-
way valve) is wired in parallel with the power to the compressor at the AUX
POWER outlet.
removed from the compressor pressure relief valve. This causes the valve to
vent all tubing from the compressor to the valve to atmospheric pressure.
8.8 The compressor pressure relief valve is an important part of the compressor
control system. Its function is to vent to atmospheric pressure all tubing leading
from the compressor to the check valve inlet on the rear of the ballast tank
when the compressor is off.
8.9 If the compressor is permitted to start against pressure, its starting current
begins to rise dramatically, causing the compressor to run hotter, increasing
Operating the compressor in this manner greatly reduces
When power is removed from the compressor it is also
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