Sullair LS-200 Operator's Manual And Parts List page 18

Section 2
DESCRIPTION
Figure 2-2B Compressor Fluid Cooling/Lubrication and Discharge System- Water-cooled
allowing compressed air to flow into the service line.
From this point on, the line air pressure is continu-
ally monitored by the Supervisor. The pressure reg-
ulator and the solenoid valve remain closed during
this phase. The inlet valve is in the fully open posi-
tion as long as the compressor is running at 100
psig ( 6.9 bar) or below.
MODULATING MODE (STANDARD CONTROL) -
100 TO 110 PSIG (6.9 TO 7.6 BAR)
If less than the rated capacity of compressed air is
being used, the line pressure will rise above 100
psig (6.9 bar), and a pressure regulator starts feed-
ing an air signal to close the inlet poppet valve,
throttling the mass of air entering the compressor
and thereby reducing the latter's air delivery. The air
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throttling of the inlet poppet valve system increases
proportionately with a rise of line pressure from 101
to 110 psig (7 to 7.6 bar).
MODULATING MODE WITH OPTIONAL SPIRAL
VALVE - 100 TO 110 PSIG (6.9 TO 7.6 BAR)
As air demand drops below the rated capacity of the
compressor, the line pressure will rise above 100
psig (6.9 bar). As a result, the differential pressure
regulator for the spiral valve gradually opens, apply-
ing air pressure to the spiral valve actuator. Air pres-
sure at the actuator expands the diaphragm. The
rack, in turn, engages with the pinion mounted on
the spiral valve shaft assembly. This results in a
rotary motion. As the spiral valve rotates, it starts
opening the bypass ports gradually. Excess air is