Sullair 20/12 Series Operator's Manual And Parts List page 22

Section 5
OPERATION
5.2 PURPOSE OF CONTROLS
CONTROL OR INDICATOR
PRESSURE RELIEF VALVE (Sump)
PRESSURE RELIEF VALVE (Interstage)
TERMINAL CHECK VALVE
SULLICON CONTROL
PILOT PRESSURE REGULATOR
PILOT VALVE
BLOWDOWN VALVE
PRESSURE SWITCH
MINIMUM PRESSURE/CHECK VALVE
HIGH DISCHARGE TEMPERATURE SWITCH
LOW FLUID PRESSURE SWITCH
INLET CYLINDER
CLOSED INLET SOLENOID VALVE
FLUID STOP VALVE PILOT VALVE
18
PURPOSE
Opens sump pressure to the atmosphere should pres-
sure inside the sump become too high (375 PSIG
[2584kPa]).
Opens inner stage to atmosphere should the pressure
become too high (140 PSIG [965kPa]).
NOTE
Under certain conditions, it may be desirable to
pipe the relief valve to the outside of the building
for inside installation.
Prevents line pressure backflow into the sump during
unload conditions and after shutdown.
Regulates the amount of air allowed to enter the air in-
let valve. This regulation is determined by the amount
of air being used at the service line.
Opens a pressure line between the sump and Sullicon
Control allowing the actuator to regulate air delivery to
air demand.
Bypasses the pressure regulator valve causing the
Sullicon Control to close the inlet butterfly valve when
the compressor reaches maximum operating pres-
sure.
Vents sump pressure to the atmosphere during unload
conditions and shutdown.
Senses service line pressure. When line pressure
reaches maximum operating pressure, the pressure
switch signals the pilot valve to unload the compressor.
Maintains a minimum pressure of 160 PSIG (1103kPa)
in the sump. This valve restricts air discharge from the
sump when the pressure falls to 160 PSIG (1103kPa).
However, full flow is allowed at normal operating pres-
sures.
Shuts the compressor down if the discharge tempera-
ture from the first stage exceeds 265_F (130_C) or the
second stage exceeds 265_F (130_C).
Shuts the compressor down if the fluid pressure down-
stream of the bearing filter drops below 90 PSIG
(621kPa).
Holds butterfly valve closed during start mode.
Prevents the inlet cylinder from opening the inlet but-
terfly valve during start--up.
Vents the fluid stop valve pilot signal upon shutdown of
the compressor.