Sullair LS-200 Operator's Manual And Parts List page 19

Figure 2-3A Control System with Supervisor Controller (without Spiral Valve)
then being returned back internally to the suction
end of the compressor unit. Now the compressor is
fully compressing only that amount of air, which is
being used. As air demand keeps dropping further,
the spiral valve keeps opening more and more until
all the bypass ports are fully open. At this point, the
spiral valve has moved into the unload (minimum)
position.
The spiral valve provides a modulation range from
100 to 50%. During this period, the pressure rises
approximately from 100 to 105 psig (6.9 to 7.2 bar).
As the air pressure exceeds 105 psig (7.2 bar), the
differential pressure regulator controlling the inlet
poppet valve starts opening and forcing the poppet
DESCRIPTION
closed, thus throttling inlet air flow to the compres-
sor. The inlet poppet valve provides a modulation
range from 50 to 40%. During this period, the pres-
sure rises approximately from 106 to 110 psig (7.3
to 7.6 bar). During this range, the spiral valve
remains in the unload position.
UNLOAD MODE - IN EXCESS OF 110 PSIG (7.6
BAR)
When a relatively small amount or no air is being
used, the service line pressure continues to rise.
When it exceeds 110 psig (7.6 bar), the Supervisor
Control System de-energizes the solenoid valve
allowing sump air pressure to be supplied directly
to close the inlet valve. Simultaneously, the sole-
Section 2
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