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2.3 SULLAIR
COMPRESSOR UNIT, FUNCTIONAL
DESCRIPTION
Sullair air compressors feature the Sullair compres-
sor unit, a single---stage, positive displacement fluid
lubricated---type compressor. This unit provides
continuous air compression to meet your needs.
Fluid is injected into the compressor unit in large
quantities where it mixes directly with the air as the
internal rotors turn, compressing the air. The fluid
flow has three basic functions:
1. As coolant, it controls the rise of air temperature
normally associated with the heat of compres-
sion.
2. Seals the leakage paths between the rotors and
the stator and also between the rotors them-
selves.
3. Acts as a lubricating film between the rotors al-
lowing 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 to the service line and the
fluid is cooled in preparation for re---injection.
With a Sullair compressor, there is no mainte-
nance or inspection of the internal parts of the
compressor unit permitted in accordance with the
terms of the warranty.
2.4 COMPRESSOR COOLING AND LUBRICATION
SYSTEM, FUNCTIONAL DESCRIPTION
Refer t o Figures
2 --- 2
brication system consists of a fluid cooler, after-
cooler, bearing fluid filter, full flow fluid strainer,
fluid stop valve, thermal valve and a water regu-
lating valve (for water---cooled models only). For
water---cooled models, a fluid cooler and aftercooler
are mounted on the compressor package. For air---
cooled models, they are mounted on separate cool-
ing packages.
The pressure in the receiver/sump causes fluid flow
by forcing the fluid from the high pressure area of
the sump to an area of lower pressure in the com-
pressor unit.
Fluid flows from the bottom of the receiver/sump to
the thermal valve. The thermal valve is fully open to
the compressor unit when the fluid temperature is
below 170_F (77_C). The fluid passes through the
thermal valve, the main fluid filter and directly to the
compressor unit.
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 strainer, and on to the compressor
NOTE
a nd
2 ---
3. The coolin g a nd lu -
unit. The strainer has an integral pressure bypass
valve.
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
an extra fine bearing filter, thus assuring properly fil-
tered lubricant for bearing supply.
The bearing filter has a replacement element and an
integral pressure bypass valve. An associated
maintenance gauge indicates when the filter needs
servicing. This gauge has a red zone setting lower
than that of the bypass valve. After the initial 50 hour
filter change, the gauge will rarely read in the red un-
der normal operating conditons.
The fluid stop valve prevents fluid from filling the
compressor unit when the compressor is shut
down. When the compressor is operating, the fluid
stop valve is held open by air pressure from the
compressor unit allowing a free flow of fluid from the
receiver/sump back to the compressor unit. On
shutdown, the compressor unit pressure is re-
duced, causing the fluid stop valve to close and iso-
late the compressor unit from the cooling system.
Water---cooled versions of the compressor have a
water---flow regulating valve which operates to con-
serve water during periods of varying load on the
compressor. This same valve automatically shuts off
the water supply when the compressor is shut
down. In addition, water---cooled models have a
water pressure switch to prevent operation with in-
adequate water pressure.
2.5 COMPRESSOR DISCHARGE SYSTEM, FUNC-
TIONAL DESCRIPTION
Refer t o Figures
2 ---
charges the compressed air/fluid mixture through a
discharge check valve into the sump. The air/fluid
mixture enters the sump and is directed against the
tank. Its direction of movement is changed and its
velocity significantly reduced, thus causing the
large droplets of fluid to fall to the bottom of the tank.
The compressed air with the remaining fluid enters
the receiver. As the compressed air passes through
nested separators (primary and secondary), the re-
maining fluid is removed from the air. The fluid re-
moved in the receiver flows to the bottom of each
separator which is in turn returned back to the com-
pressor through two scavenger lines. Some fluid
will drop to the bottom of the receiver prior to the air
entering the separator elements. This fluid is also re-
turned to the compressor via another scavenger
tube. Sight glasses are provided in the scavenger
lines to observe this fluid flow. There are also orifices
on these lines (protected by strainers to assure
proper flow). A separator differential pressure
gauge, located on the instrument panel, is provided
to facilitate maintenance of the separators. All tanks,
sump and receiver are ASME pressure vessels.
A minimum pressure valve is provided to assure
minimum sump pressure of 50 PSIG (345kPa). This
Section 2
DESCRIPTION
4. The compressor unit dis -
5
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