| It is the fourth utility. Compressed air,
along with gas, electricity and water, is essential to most modern industrial
and commercial operations. It runs tools and machinery, provides power
for material handling systems, and ensures clean, breathable air in contaminated
environments. It is used by virtually every industrial segment from aircraft
and automobiles to dairies, fish farming, and textiles. |
| A plant's expense for its compressed air is
often thought of only in terms of the cost of the equipment. Energy costs,
however, represent as much as 70% of the total expense in producing compressed
air. As electricity rates escalate across the nation and the cost of maintenance
and repair increases, selecting the most efficient and reliable compressor
becomes critical. |
| Rotary Screw Compressor: The Plant Workhorse |
| Rotary screw compressors operate on the principle
of positive displacement. Filtered air enters the inlet of the airend where
male and female rotors unmesh. The air is trapped between the rotors and
the airend housing. This space is reduced as the rotors remesh on the opposite
side of the airend. Thus, the air is compressed and moved to the discharge
port. |
| Oil injected into the housing mixes with the
air to seal, lubricate, and remove the heat generated by compression. This
oil forms a thin film between the rotors that virtually eliminates metal-to-metal
contact and wear. The oil is separated from the compressed air, cooled,
filtered, and returned to the injection point. The compressed air then
passes through an aftercooler to reduce its temperature and is ready for
the air treatment equipment. |
| Types of
Air Compressors |
1. Dynamic Centrifugal/Axial - Use
a rotating impeller to impart velocity to the air, which is converted to
pressure.
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Rotary - Compress air through the
action of rotating elements. Most common types are rotary screw, which
uses rotating male and female rotors to compress air, and sliding vane,
which uses radially moving vanes.
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Reciprocating - Compress air through
the use of a reciprocating piston.
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| Select air compressors
based on your plant needs. Positive displacement compressors take in quantities
of air and mechanically reduce the space occupied by the air to increase
pressure. Dynamic compressors use the mechanical action of rotating impellers
to transfer pressure to the air. |
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Evaluating a Compressed
Air System / Selecting an Air Compressor
/ Maintenance / Troubleshooting
/ Glossary and Reference Data
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© Copyright 2007
Maintenance Resources, Inc.
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Phone: 812.877.7119
- Fax: 812.877.7116 - E-Mail: info@maintenanceresources.com
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Address: 1983 North Hunt
Street - Terre Haute, IN 47805
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