Sullair LS-120 series Operators Manual And Parts Lists page 34

Section 5
OPERATION- ELECTRO-MECHANICAL
5.2 PURPOSE OF CONTROLS- STANDARD ELECTRO-MECHANICAL
CONTROL OR INDICATOR
POWER ON ( ) LED
ON LED
-SOLID (CONTINUOUS) LIGHT
-BLINKING LIGHT
AUTO LED
SEPARATOR RETURN LINE SIGHT GLASS
THERMAL VALVE
MINIMUM PRESSURE/CHECK VALVE
COMPRESSOR DISCHARGE
WATER PRESSURE SWITCH
(water-cooled compressors only)
PRESSURE RELIEF VALVE
MODULATING INLET VALVE
PRESSURE REGULATOR
SOLENOID VALVE
28
(CONTINUED)
PURPOSE
Indicates when the starter is receiving power.
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.
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 180°F
(82°C); 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 receiv-
er/sump when pressure falls to 55 psig (3.8 bar). Also pre-
vents backflow into the sump during unload conditions and
after shutdown.
Designed to shut the compressor down when the discharge
TEMPERATURE SWITCH temperature reaches 235°F
(113°C).
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 compres-
sor. 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.
Allows a pressure signal to reach the air inlet 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
pressure. Also activates blow-down valve.