ABSTRACT
The reason that this article concentrates on positive displacement compressors as a group is that they can be found practically anywhere. They are the hearts of refrigerators, air conditioners and heat pumps. They supply compressed air to machine tools, construction equipment such as jack hammers, medical devices such as dentist’s drills and diving equipment. They pump natural gas through pipelines and compress oxygen and nitrogen. It is estimated that in the United States alone, there are more than 400 million compressors in existence as this is written. A typical household may have as many as six compressors: in a heat pump and central air conditioning system, one or two auxiliary window air conditioners, one or two refrigerators and freezers, and one shop air compressor. Industrial applications are numerous; sizes range from a fractional-horsepower compressor in a household refrigerator to thousand and more horsepower compressors to pump natural gas. As a group, they are not only one of the largest energy users, but also one of the largest noise polluters.
