Sullair LS20T - General; Purpose of Controls

Section 6
OPERATION
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6.1 GENERAL
While Sullair has built into this compressor a com-
prehensive array of controls and indicators to
assure you that it is operating properly, you will
want to recognize and interpret the reading which
will call for service or indicate the beginning of a
malfunction. Before starting your Sullair compres-
sor, read this section thoroughly and familiarize
yourself with the controls and indicators - their pur-
pose, location and use.
CONTINUED...
6.2 PURPOSE OF CONTROLS
CONTROL OR INDICATION PURPOSE
FLUID LEVEL SIGHT GLASS Monitors fluid level in the sump. Proper level should fill the sight
glass. Check level when the compressor is shut down. DO NOT
OVERFILL.
SEPARATOR RETURN LINE SIGHT
GLASS
Used to indicate fluid flow in the return lines. When the compres-
sor is running at full load, fluid flow should be visible in this sight
glass. There may b little or no flow when the compressor is run-
ning unloaded, but a sluggish flow at full load indicates a need to
clean the return line strainer.
FLUID STOP VALVE Cuts off flow of fluid to compressor unit at compressor shutdown
and allows flow of fluid to the unit on startup.
DISCHARGE CHECK VALVE Cuts off the reverse flow of air/fluid mixture through compressor
discharge system at compressor shutdown.
THERMAL VALVE Regulates flow of fluid to and around the cooler. Designed to
maintain a minimum operating temperature of 220ºF (104ºC).
Also used for fast warm-up on startup.
MINIMUM PRESSURE/CHECK
VALVE
Maintains minimum of 160 psig (11bar) in the compressor sump.
Valve piston restricts receiver air discharge from receiver/sump
when pressure falls to 160 psig (11bar). Prevents line pressure
backflow into the sump during unload conditions and after shut-
down.
PRESSURE RELIEF VALVE (SUMP) Opens sump pressure to the atmosphere should pressure inside
the sump becomes too high (375 psig [25.8 bar]). Operation of
this valve indicates that the high pressure transducer is either
faulty or out of adjustment.
PRESSURE RELIEF VALVE (INTER-
STAGE)
Opens interstage of compressor to atmosphere should the pres-
sure become too high (150 psig [10.3 bar]). Operation of this
valve indicates unit pressurization during shutdown. Causes may
be plugged control lines, faulty discharge check
valve, or faulty fluid stop valve.
INLET POPPET VALVE Regulates the amount of air allowed to enter the air inlet valve.
This regulation is determined by the amount of air being used at
the service line.
PRESSURE REGULATOR (INLET
POPPET VALVE)
Opens a pressure line between the sump and inlet poppet valve
allowing to regulate air delivery according to the air demand.
PRESSURE REGULATOR
(UNLOAD)
Opens a pressure line between the sump and the inlet poppet
valve to regulate the unload pressure.