Sullair LS20TS, Operator'S Manual And Parts List

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Section 2
DESCRIPTION
9
reduced. The unload pressure regulator is set to
maintain the unload pressure at the designated
value, 150 psig (10.3 bar). At this time, the com-
pressor is in the unload mode.
When the line pressure drops back to the load point
(cut-in pressure) of the pressure transducer, usual-
ly 350 psig (24.1 bar), the compressor will change
state back to the modulating mode as discussed
earlier. This cycle will repeat itself, maintaining the
demand required on the system line supply.
SHUTDOWN MODE
When the compressor is shut down based on a
manual shutdown, a safety shutdown or an auto-
matic shutdown from the Supervisor II touch pad,
the unload solenoid valve is energized allowing air
to flow through the check valve and into the poppet
valve keeping the inlet poppet valve closed. This
also opens the blowdown valve to allow com-
pressed air to vent back above inlet poppet valve
through the inlet filter. The control lines are proper-
ly sized and routed to allow the compressed air to
relieve to atmosphere rather than below the inlet
poppet valve.
If the compressor Supervisor II is in the automatic
mode, the compressor will shut down after running
unloaded for a specific amount of time. The reverse
also holds true, if the system line pressure requires
additional compressed air, the compressor will start
automatically to satisfy this demand.