Quincy Compressor 50093-103 - Manual (Page 36)

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Section 2 - Description
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QSVI Vacuum Pumps
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Principles of Vacuum Pump Operation
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Air Flow
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Fluid Flow & Cooling System
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Fluid Coolers
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Air/Fluid Reservoir & Air/Fluid Separator Element
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Auto Dual with Modulation
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Auto Demand – Optional
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Electrical System
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Indicators & Gauges
QSVI Series Vacuum Pumps
The QSVI line of rotary screw vacuum pumps are
single stage, positive displacement, fluid flooded,
rotary screw type units. They consist essentially of two
rotors that resemble worm gears. The male rotor is direct
driven through a flexible coupling on all QSVI's except the
QSVI 40. The male rotor has four lobes that mesh with six
grooves in the female rotor. Both rotors are contained in a
rotor housing that has two parallel axis and adjoining
bores. There is an air inlet part located at the power input
end of the vacuum pump and a discharge port located at
the opposite end. Both rotors are mounted
in anti friction bearings at both the suction and discharge
ends. The electric motor, airend and associated equipment
are mounted on a welded structural frame.
Radial loads are carried on cylindrical roller bearings on
the power or suction end of the vacuum pump. Radial and
axial loads are carried on tapered roller bearings at the
discharge end of the vacuum pump.
Fluid circulation is maintained by an external fluid pump
directly driven by the rotor.
Principles of Vacuum Pump Operation
As the rotors turn, air is drawn into the rotor housing
through the inlet port. This volume of trapped air extends
the entire length of the two rotors initially and is
prevented from escaping by the unported area of the rotor
housing wall. As rotation continues, the air at the inlet
side is carried to the discharge side and forced out the
discharge port, the discharge pipe, and into the air/fluid
reservoir where it is discharged to the atmosphere through
a fluid separator element. The compression cycle of a
rotary vacuum pump is a continuous process from intake
to discharge. The airend consists of two rotors in
constant mesh, housed in a cylinder with two parallel
adjoining bores. All parts are machined to exacting
tolerances.
Compression Cycle