Compressor Discharge System, Functional Description; Control System, Functional Description- Standard Electro-Mechanical - Sullair LS-120 series Operators Manual And Parts Lists

[190ºF (88ºC) for 24KT, and rated pressures 150
psig and above]. The fluid passes through the ther-
mal valve, the main filter and directly to the com-
pressor unit where it lubricates, cools and seals the
rotors and the compression chamber.
As the discharge temperature rises above 170°F
(77°C), due to the heat of compression, the thermal
valve begins to close and a portion of the fluid then
flows through the cooler. From the cooler the fluid
flows to the main filter and then on to the compres-
sor unit.
A portion of the fluid flowing to the compressor is
routed to the anti-friction bearings which support
the rotors inside the compressor unit. Prior to enter-
ing the compressor unit, this fluid is taken through
the fluid filter, thus assuring properly filtered lubri-
cant for bearing supply.
The fluid filter has a replacement element and an
integral pressure bypass valve. A gauge on the
instrument panel shows red when the filter needs
servicing. This gauge has a pressure setting lower
than that of the bypass valve. The gauge 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. Return lines (or
scavenge tubes) lead 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. A
and 2-4. The compressor unit
visual sight glass is located on the return line to
observe this fluid flow. There is also an orifice in
each 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 1
ppm (parts per million). A gauge, located on the
instrument panel, shows red if abnormal pressure
drop through the separator develops. At this time,
separator element replacement is necessary. This
gauge must be checked with the compressor run-
ning fully loaded.
A minimum pressure/check valve, located down-
stream from the separator, assures a minimum
receiver pressure of 50 psig (3.4 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
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 235°F (113°C).
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- STANDARD ELECTRO-MECHANICAL
Refer to Figure 2-5. The purpose of the compressor
Control System is to regulate the compressor air
intake to match the amount of compressed air being
used. At approximately 10 psig (0.7 bar) air line
over-pressure, the control system will automatically
blow down the compressor and greatly reduce the
unload power consumption.
The Control System consists of an inlet valve,
(located on the compressor air inlet), blowdown
valve, solenoid valve, pressure switch, and a
pressure regulator. The functional descriptions of
the Control System are given below in four distinct
phases of compressor operation. The following
Section 2
DESCRIPTION
7