getting the most for your money in a compressor investment

Types of air compressors

Compressed air is the fourth utility. Along with gas, electricity, and water, it 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 viewed only in terms of the equipment. Every cost, however, represents 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.

Air compressors
Dynamic Positive displacement
Centrifugal/axial Rotary Reciprocating
Use a rotating impeller to impart velocity to the air, which is converted to pressure. 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. Compress air through the use of a reciprocating piston.
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.

The rotary screw compressor: the plant workhorse

basic operation of a rotary screw compressor
Basic operation of a rotary screw compressor

Rotary screw compressors operate on the principle of positive displacement. Filtered air enters the inlet of the airend where male and female rotors un-mesh. The air is trapped between the rotors and the airend housing. This space is reduced as the rotors re-mesh on the opposite side of the airend. Thus, the air is compressed and moved to the discharge port. Cooling fluid injected into the housing mixes with the air to seal, lubricate, and remove the heat generated by compression. This fluid forms a thin film between the rotors that virtually eliminates metal-to-metal contact and wear. The fluid is separated from the compressed air, cooled, filtered, and returned to the injection point. The compressed air passes through an aftercooler to reduce its temperature and is ready for the air treatment equipment.