Section 5
COMPRESSOR SYSTEMS
18
control valves. The inlet air filters are also mounted
for easy access and servicing.
5.3 SULLAIR COMPRESSOR UNIT, FUNCTIONAL
DESCRIPTION
Sullair tandem air compressors feature the Sullair
compressor unit, a two---stage, positive displace-
ment 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.
NOTE
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.
5.4 COMPRESSOR COOLING AND LUBRICATION
SYSTEM, FUNCTIONAL DESCRIPTION
R e f e r t o F i g u r e s 5 --- 2 , 5 --- 3 , 5 --- 4 a n d 5 --- 5 . T h e
cooling and lubrication system consists of a fluid
cooler, aftercooler, full flow fluid filter, fluid stop
valve, thermal valve and a water regulating
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
cooling 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 discharge tempera-
ture 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 ther-
mal 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, (or filters) and on to the
compressor unit. Each fluid filter has a replacement
element and an integral pressure bypass valve.
The fluid stop valve prevents fluid from filling the
compressor unit w hen 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 compre ssor 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
conserve 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
inadequate water pressure.
5.5 COMPRESSOR DISCHARGE SYSTEM, FUNC-
TIONAL DESCRIPTION (200, 250 and
300HP/150, 187 AND 225KW)
R e f e r t o F i g u r e s 5 --- 2 , 5 --- 4 a n d 5 --- 6 . T h e c o m p r e s -
sor unit discharges the compressed air/fluid mix-
ture through a discharge check valve into the com-
bination receiver/sump. The dischar ge check valve
prevents air/fluid in the receiver from returning to
the compression chamber after the compressor
has been shut down. The receiver has three func-
tions:
1. It acts as a primary fluid separator.
2. It serves as the compressor fluid sump.
3. It houses the final fluid/air separator elements.
The compressed air/fluid mixture enters the re-
ceiver and is directed against the ends of the tank.
The direction of movement is changed and its ve-
locity significantly reduced, thus causing the large
droplets of fluid to fall to the bottom of the receiver/
sump. The fractional percentage of fluid remaining
in the compressed air collects on the surface of the
nested separator elements (primary and secon-
dary) as the compressed air flows through them.
Two return lines (or scavenge tubes) lead from the
bottom of each separator element to the low pres-
sure inlet region of the compressor unit. Fluid col-
lecting on the bottom of each separator is returned
to the compressor by a pressure difference be-
tween the receiver and the compressor inlet. Sight
glasses are located in the return lines to observe
this fluid flow. By pressing the ∆P1 pad on the Su-
pervisor, the operator can monitor the condition of
the separator elements by reading the differential
pressure on the digital display. At a differential of 10
PSID (0.7 bar), or greater, the operator will be told
to service the separator elements. At this time,
separator element replacement is necessary.
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