Section 4
COMPRESSOR SYSTEMS
14
Figure 4-2 Integrated Compressor System
an inlet valve, (located on the compressor air inlet),
blowdown valve, solenoid valve, pressure switch,
and a pressure regulator. The functional descrip-
tions of the control system are given below in four
distinct phases of compressor operation. The fol-
lowing guidelines apply to all STANDARD ES--11
Series compressors. For explanatory purposes this
description will apply to a compressor with an oper-
ating pressure range of 125 to 135 psig (8.6 to 9.3
bar). A compressor with any other pressure range
would operate in the same manner excepting stated
pressures.
START -- 0 TO 50 PSIG (0 TO 3.4 BAR)
When the compressor
“I” (START)
switch position
is engaged momentarily and released, the sump
pressure will quickly rise from 0 to 50 psig (0 to 3.4
bar). During this period both the pressure regulator
and the solenoid valve are closed, the inlet valve is
fully open due to inlet air flow, and the compressor
pumps at full rated capacity. The rising compressor
air pressure is isolated from the service line in this
phase by the minimum pressure valve, set at
approximately 50 psig (3.4 bar).
NORMAL OPERATING MODE -- 50 TO 125 PSIG
(3.4 TO 8.6 BAR )
When the pressure air rises above 50 psig (3.4 bar),
the minimum pressure/check valve opens and deliv-
ers compressed air to the service line. From this
point on, the line air pressure is continually moni-
tored by a line pressure gauge and a pressure
switch usually set at 125 psig (8.6 bar). The pres-
sure regulator and the solenoid valve remain closed
during this phase. The inlet valve remains fully open
for maximum capacity.
MODULATING MODE -- 125 TO 135 PSIG (8.6 TO
9.3 BAR)
If less than the rated capacity of compressed air is
being used, the service line pressure will rise above
125 psig (8.6 bar). The pressure regulator valve
gradually opens, applying air pressure through the
control line to the inlet valve piston. This causes the
inlet valve to partially close reducing the amount of
air entering the compressor until it matches the
amount of air being used. The control system func-
tions continually in this manner, between the limits
of 125 to 135 psig (8.6 to 9.3 bar), in response to va-
rying demands from the service line.
The pressure regulator has an orifice which vents a
small amount of air to the atmosphere when the
pressure regulator controls the inlet valve. The ori-
fice also bleeds any accumulated moisture from the
control lines.
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