Air Inlet System, Functional Description - Sullair LS-20T Operator's Manual

Section 2
DESCRIPTION
MODULATING MODE – 340 TO 360PSI (2344 TO
2482KPA)
If less than the rated capacity of compressed air is
being utilized, the service line pressure will rise
above the 340psi (2344kPa). The control pressure
regulating valve gradually opens, applying air pres-
sure to the control side of the poppet valve, which
partially closes the poppet valve on the compres-
sor air inlet reducing the amount of air entering the
compressor until it matches the demand. The con-
trol system functions continually in this manner, be-
tween the limits of 340 to 360psi (2344 to 2482kPa)
in response to varying demands from the service
line. The control pressure regulating valve has an
orifice, which vents a small amount of air to the at-
mosphere while controlling the poppet valve.
UNLOAD MODE
(2482KPA)
As the demand is reduced, the line pressure rise
above 360psi (2482kPa). This de---energizes the
unload solenoid valve allowing air to flow through
the low---pressure regulator and check valve which
forces the poppet valve to the closed position. The
blowdown valve is also opened which allows dis-
charge air to flow back to the compressor inlet,
both above and below the poppet valve. The low---
pressure regulator will modulate the inlet valve to
maintain an unloaded
(1034kPa).
When the line pressure drops back to the low pres-
sure setting (cut---in pressure). This causes the
blowdown solenoid valve to be energized which
stops air from flowing through the low---pressure
regulating valve along with through the check valve
and to the poppet valve. This allows the poppet
valve to modulate as specified in the previous sec-
tions.
SHUTDOWN MODE
When the compressor is shut down based on a
manual shutdown, a safety shutdown or an auto-
matic shutdown from the supervisor controller
touch pad, the unload solenoid valve is de---ener-
gized allowing air to flow through the check valve
and into the poppet valve keeping the poppet valve
closed. This also opens the blowdown valve to al-
low compressed air to vent back to above the pop-
10
– EXCESS OF 360PSI
pressure of 150psi
pet valve, which is to atmosphere through the air in-
let filter.
2.7 AIR INLET SYSTEM, FUNCTIONAL DESCRIP-
TION
Refer to Figur e 2 --- 3 . The c ompr essor inlet systems
consists of a dry---type air filter, a restriction gauge,
inlet cylinder, Sullicon Control and an air inlet valve.
The restriction gauge, located on the compressor
instrument panel, indicates when air filter mainte-
nance is required.
The butterfly---type air inlet valve directly controls
the amount of air intake to the compressor in re-
sponse to the operation of the Sullicon Control
(Section 2.6). The inlet cylinder holds the butterfly
valve closed during the compressor start mode.
Figure 2 ---3 Air Inlet System