600H, 700HH, 750, 750H, 750HH, 825, 900H, 1050 USER MANUAL SECTION 2
24
2.3 SULLAIR COMPRESSOR
UNIT, FUNCTIONAL
DESCRIPTION
Sullair compressors feature the Sullair compressor
unit, a single-stage, positive displacement, flood
lubricated-type compressor. This unit provides
continuous compression to meet your needs.
Sullair compressors are factory-filled with Sullair
AWF lubricant. For more information on fluid fill, refer
to “Lubrication Guide—Compressor” on page 65.
Fluid is injected into the compressor unit hoses and
mixes directly with the air as the rotors turn,
compressing the air. The fluid flow has three basic
functions:
1. As coolant, it controls the rise of air tempera-
ture normally associated with the heat of
compression.
2. Seals the clearance paths between the
rotors and the stator and also between the
rotors themselves.
3. Acts as a lubricating film between the rotors
allowing one rotor to directly drive the other,
which is an idler.
After the air/fluid mixture is discharged from the
compressor unit, the fluid is separated from the air.
At this time, the air flows through an aftercooler and
moisture separator, if equipped, then to your service
line.
2.4 COMPRESSOR COOLING
AND LUBRICATION
SYSTEM, FUNCTIONAL
DESCRIPTION
Refer to Figure 2-2. The compressor cooling and
lubrication system is designed to provide adequate
lubrication as well as maintain the proper operating
temperature of the compressor. In addition to the
cooler and fan, the system consists of a main filter
and thermal valve. The fan is hydraulically driven,
refer to Section 2.18 for more detail.
Fluid is used in the system as a coolant and a
lubricant. The fluid is housed in the receiver tank.
Upon start up, the fluid temperature is cool, and
routing to the cooler is not required. The fluid first
enters the thermal valve and then flows on to the
compressor unit, bypassing the cooler. As the
compressor continues to operate, the temperature of
the fluid rises and the thermal valve element begins
to shift. This forces a portion of the fluid to the fluid
cooler. The cooler is a radiator-type that works in
conjunction with the hydraulic fan. The fan forces air
through the cooler removing the heat of compression
from the fluid. From the cooler, the fluid is routed
back to the thermal valve.
Before the temperature of the fluid reaches the valve
set point, cooled fluid is mixed with warmer fluid.
When the temperature of the fluid reaches 170°F
(77°C), the thermal element shifts completely
causing all fluid to flow to the cooler. The thermal
valve incorporates a pressure relief valve, which
allows fluid to bypass the cooler, if the cooler
becomes plugged or frozen. This helps assure that
fluid will continue to be provided to the compressor
for lubrication. After the fluid passes through the
thermal valve it is then directed through the main
fluid filter. There, the fluid is filtered in preparation for
injection into the compression chamber and bearings
of the compressor unit. The filter has a replaceable
element and a built-in bypass valve which allows the
fluid to flow even when the filter element becomes
plugged and requires changing or when the viscosity
of the fluid is too high for adequate flow. After the
fluid is properly filtered, it then flows on to the
compressor unit where it lubricates, seals and cools
the compression chamber as well as lubricates the
bearings and gears.
NOTE
With a Sullair compressor, there is no main-
tenance or inspection of the internal parts
of the compressor unit permitted in accor-
dance with the terms of the warranty.
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