Product Manual

CAP881
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3.0 General Description
COMPRESSOR
The compressor assembly is an oil flooded positive displacement, single stage, helical screw type
unit consisting of two rotors or screws supported axially by roller bearings and enclosed in a
housing or stator as depicted in the sectional view Figure 3-1.
Figure 3-1
Compressor Assembly
In operation, as depicted below in the compression cycle (Ref. Figure 3-2), air enters the compressor
through the inlet port becomes trapped between the helical lobes of the main rotor and the matching
grooves of the secondary rotor (A). As the rotors turn air is trapped in the cavity created by the
mashing lobe and groove and reduced in volume or “compressed”. It is then pushed through the
successive cavities (B) until it reaches the discharge end of the compressor (C) and is sent to the oil
separator.
During the compression cycle, oil is injected into the compressor for the purpose of dissipating the
heat of compression and to seal the internal clearances. The compressed air laden with oil leaves the
compressor through the discharge port and enters a reservoir where the oil and air are separated. This
process delivers a smooth flow of compressed air at the desired pressure.
Figure 3-2
Compression Cycle
INLET
DISCHARGE
MAIN ROTOR
SECONDARY
ROTOR
A B C