Sullair 20/12 500 CFM, Operator'S Manual And Parts List

Page: 22 / 66

Section 5
OPERATION
18
5.2 PURPOSE OF CONTROLS
CONTROL OR INDICATOR PURPOSE
PRESSURE RELIEF VALVE (Sump) Opens sump pressure to the atmosphere should pres-
sure inside the sump become too high (375 PSIG
[2584kPa]).
PRESSURE RELIEF VALVE (Interstage) 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.
TERMINAL CHECK VALVE Prevents line pressure backflow into the sump during
unload conditions and after shutdown.
SULLICON CONTROL 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.
PILOT PRESSURE REGULATOR Opens a pressure line between the sump and Sullicon
Control allowing the actuator to regulate air delivery to
air demand.
PILOT VALVE Bypasses the pressure regulator valve causing the
Sullicon Control to close the inlet butterfly valve when
the compressor reaches maximum operating pres-
sure.
BLOWDOWN VALVE Vents sump pressure to the atmosphere during unload
conditions and shutdown.
PRESSURE SWITCH Senses service line pressure. When line pressure
reaches maximum operating pressure, the pressure
switch signals the pilot valve to unload the compressor.
MINIMUM PRESSURE/CHECK VALVE 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.
HIGH DISCHARGE TEMPERATURE SWITCH 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).
LOW FLUID PRESSURE SWITCH Shuts the compressor down if the fluid pressure down-
stream of the bearing filter drops below 90 PSIG
(621kPa).
INLET CYLINDER Holds butterfly valve closed during start mode.
CLOSED INLET SOLENOID VALVE Prevents the inlet cylinder from opening the inlet but-
terfly valve during start--up.
FLUID STOP VALVE PILOT VALVE Vents the fluid stop valve pilot signal upon shutdown of
the compressor.