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Vacuum Pump Industry Information
Vacuum pumps are basically devices used to create a
vacuum. The vacuum pump changes the mechanical force of a rotating shaft
to pneumatic force by removing air and other gases and releasing them
into the atmosphere or holding them on surfaces within the pump. The
amount of energy produced depends on the force for all vacuum applications.
Vacuum pumps are either positive displacement or non-positive displacement.
A positive displacement pump pulls a constant volume of air despite variations
in the vacuum levels. Nonpositive displacement vacuum pumps use changes
in kinetic energy to remove air from a system. The most important advantage
of this design is its ability to supply very high volume flow rates that
are much higher than possible with any of the positive displacement designs.
Both types of pumps mentioned could be either or oil-free.
The oil lubricated types have advantages in that they are able to provide
a higher level of vacuum because the oil provides a greater seal between
moving parts. Oil-free pumps are useful for pumps that will be mounted
in inaccessible or remote locations. They are also used in the food and
pharmaceutical industries where it is necessary to keep the product free
from contaminants.
The standard types of positive displacement pumps are the piston, diaphragm,
rocking piston, rotary vane, lobed rotor and rotor screw designs. Piston
pumps consist of rotating pistons of varying stroke lengths that pump
fluids through check valves. Diaphragm pumps consist of one or two flexible
diaphragms that pulsate to displace fluid, while check valves control
the direction of the fluid flow. Rocking piston pumps are basically a
combination of diaphragm and piston pumps. Rotary vane pumps have an
impeller made of rigid material and are useful for high-pressure or low-shear
applications. Lobed rotor pumps have lobe-shaped rotors that gently fill
with and dispense fluids containing soft particles, solids and highly
viscous fluids. Rotary screw pumps have capabilities that are similar
to the piston pumps in terms of vacuum, but air removal is pulse-free.
The standard type of nonpositive displacement vacuum pumps are the centrifugal,
axial-flow and regenerative designs. Centrifugal pumps have a rotating
vanned disk that is attached to a drive shaft. As it spins, the drive
shaft moves fluid without pulsation. The outlet can be restricted without
damaging the pump. Axial-flow pumps are designed to have a fluid flow
parallel to an axis of rotation, similar to a turbine. Regenerative nonpositive
displacement pumps consist of a series of pumps joined together to increase
and maintain pressure.
All of us benefit from vacuum technology, whether wearing a pair of glasses,
watching TV, listening to music, using a PC or driving a car. The manufacturing
of semiconductors, CDs and DVDs, eyeglasses and the coating of heavy-duty
mechanical tools are a few examples in which vacuum technology is applied.
Vacuum pumps are used for vacuum distillation and the processing of food
and in devices such as vacuum tubes, vacuum bottles, barometers and research
equipment. Industries in which vacuum pumps and vacuum generators are
commonly used include chemical and corrosive gas, food processing, manufacturing
processing, medical and laboratory, packaging, power generation, pharmaceutical/sanitary
and semiconductor manufacturing industries. Vacuum pumps are also used
to improve the efficiency of steam heating systems. Different types of
pumps are used for industrial gripping and chucking, laboratory degassing
and purification in the fields of chemical and semiconductor processing.
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