Compressor Discharge System, Functional Description; Control System, Functional Description- Supervisor Controller - Sullair LS20 Operator's Manual And Parts List

icing. This indicator has a pressure setting lower
than that of the bypass valve. The indicator should
be checked with compressor running at full system
pressure.
Water-cooled models have a water pressure switch
to prevent operation with inadequate water pres-
sure.
2.5 COMPRESSOR DISCHARGE SYSTEM, FUNC-
TIONAL DESCRIPTION
Refer to Figures 2-3
discharges the compressed air/fluid mixture into the
combination receiver/sump.
The receiver has three basic functions:
1. It acts as a primary fluid separator.
2. Serves as the compressor fluid sump.
3. Houses the final fluid separator.
The compressed air/fluid mixture enters the receiv-
er and is directed against the internal baffle. The
direction of movement is changed and its velocity
significantly reduced, thus causing large droplets of
fluid to form and fall to the bottom of the
receiver/sump. The fractional percentage of fluid
remaining in the compressed air collects on the sur-
face of the separator element as the compressed
air flows through the separator. A return line (or
scavenge tube) leads from the bottom of the sepa-
rator element to the inlet region of the compressor
unit. Fluid collecting on the bottom of the separator
is returned to the compressor by a pressure differ-
ential between the receiver and the compressor
inlet. A visual sight glass is located on the return line
to observe this fluid flow. There is also an orifice in
this return line (protected by a strainer) to assure
proper flow. A secondary separator element with a
separate return line, strainer, sight glass and orifice
further reduce the fluid carry-over to less than 2
ppm (parts per million). An indicator, located on the
instrument panel, shows if abnormal pressure drop
through the separator develops. At this time, sepa-
rator element replacement is necessary. This indi-
cator must be checked with the compressor running
fully loaded.
A minimum pressure/check valve, located down-
stream from the separator, assures a minimum
receiver pressure of 50 psig (3.5 bar) during loaded
conditions. This pressure is necessary for proper
air/fluid separation and proper fluid circulation.
A terminal check valve is incorporated into the min-
imum pressure/check valve to prevent compressed
air in the service line from bleeding back into the
receiver on shutdown and during operation of the
and 2-4. The compressor unit
compressor in an unloaded condition.
A pressure relief valve (located on the wet side of
the separator) is set to open if the sump pressure
exceeds the sump tank rating. A temperature switch
will shut down the compressor if the discharge tem-
perature reaches 235ºF (113ºC).
DO NOT remove caps, plugs, and/or other compo-
nents when compressor is running or pressurized.
Stop compressor and relieve all internal pressure
before doing so.
Fluid is added to the sump via a capped fluid filler
opening, placed low on the tank to prevent overfill-
ing of the sump. A sight glass enables the operator
to visually monitor the sump fluid level.
2.6 CONTROL SYSTEM, FUNCTIONAL DESCRIP-
TION- SUPERVISOR CONTROLLER™
Refer to Figure 2-5A. The purpose of the compres-
sor Control System is to regulate the amount of air
being compressed to match the amount of com-
pressed air being used. The Capacity Control
System consists of a solenoid valve, regulator
valve and an inlet valve. The functional description
of the Control System is described below in four dis-
tinct phases of operation. The following description
text applies to all LS20 series compressors with
optional Supervisor Controller. For explanatory pur-
poses, this description will apply to a compressor
with an operating range of 100 to 110 psig (6.9 to
7.6 bar). A compressor with any other pressure
range would operate in the same manner except
stated pressures.
Always refer to the machine nameplate for
designed operating pressure.
START MODE - 0 TO 50 PSIG (0 TO 3.5 BAR)
When the compressor "I" (START)
depressed, the sump pressure will quickly rise from
0 to 50 psig (0 - 3.4 bar). During this period, both
the pressure regulator and the solenoid valve are
closed, the inlet valve is fully open and the com-
pressor pumps at full rated capacity. The rising
compressor air pressure is isolated from the service
line in this phase by the minimum pressure valve
set at approximately 50 psig (3.4 bar).
Closed Inlet Start- (Wye-delta or Solid-State start-
ing) applies dry-sump or service air pressure
through a solenoid valve to hold the inlet valve
closed allowing the compressor to start unloaded.
After a preset time (4-6 seconds) the controller will
Section 2
DESCRIPTION
pad is
9