Sullair LS20 Operator's Manual And Parts List page 48

Section 8
OPERATION- ELECTRO-MECHANICAL
8.2 PURPOSE OF CONTROLS- ELECTRO-MECHANICAL (CONTINUED)
CONTROL OR INDICATOR
ON LED
-SOLID (CONTINUOUS) LIGHT
-BLINKING LIGHT
AUTO LED
SEPARATOR RETURN
GLASS
THERMAL VALVE
MINIMUM PRESSURE/CHECK VALVE
COMPRESSOR DISCHARGE
TEMPERATURE SWITCH
WATER PRESSURE SWITCH
(water-cooled compressors only)
PRESSURE RELIEF VALVE
MODULATING INLET VALVE
SPIRAL VALVE (OPTIONAL)
PRESSURE REGULATOR
SOLENOID VALVE
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PURPOSE
Indicates when compressor is in operation:
Indicates that machine is running.
Indicates that machine is in `standby' mode, and may start at
any moment without any more user intervention.
Indicates when compressor is in auto mode.
LINE SIGHT
Used to indicate fluid flow in the return line. When the com-
pressor is running at full load, fluid flow should be visible in
this sight glass. There may be little or no flow when the com-
pressor is running unloaded, but a sluggish flow at full load
indicates a need to clean the return line strainer.
Regulates flow of fluid to and around the cooler. It is designed
to maintain a minimum operating temperature of 180ºF
(82ºC); use for fast warm-up on start-up.
Maintains minimum of 55 psig (3.8 bar) in the compressor
sump. Valve piston restricts receiver air discharge from
receiver/sump when pressure falls to 55 psig (3.8 bar). Also
prevents backflow into the sump during unload conditions and
after shutdown.
Designed to shut the compressor down when the discharge
temperature reaches 235ºF (113ºC).
It prevents operation when water pressure of compressor
is inadequate.
Opens sump pressure to the atmosphere should pressure
inside the sump become too high. Operation of this valve indi-
cates that the high pressure switch is either faulty or out of
adjustment.
Regulates the amount of air allowed to enter the air
compressor. This regulation is determined by the amount of
air being used at the service line. Also acts as a check valve
to prevent reverse compressor rotation at shut down.
Internally bypasses and controls the air flow capacity of the
compressor, in order to match air supply to the demand. This
device is optional.
Allows a pressure signal to reach the air inlet valve or spiral
valve to control air delivery according to demand.
Bypasses the pressure regulator valve causing the inlet valve
to close when the compressor reaches maximum operating