Are There Advantages to Reciprocating Air Compressors?

Reciprocating Air CompressorReciprocating air compressors are the old work horses of industrial strength air compression, being popular since the early 1900s in industrial applications and remain the most common type of compressors for intermittent use, like the type of air compressor used in mechanic’s shops and the like. As such they have a well deserved reputation as dependable they still offer a number of advantages over the rotary screw compressors that have taken over a lot of the jobs that were once exclusively the domain of reciprocating air compressors.

A reciprocating air compressor operates by positive displacement, or, to put it another way, it increases the air pressure by “squishing” ever increasing amounts of air into a confined chamber. This process is accomplished using a piston, which constantly pulls in more air into the chamber, thereby putting it under increased pressure. This basic mechanism is how the system works, though the number of variations is extremely wide, as one would expect with any sort of technology with more than a century of history behind it. Single action compressors only use one side of the piston, while dual action compressors use both sides. Some reciprocating compressors have two or more chambers, which leads to the compressed air being recompressed using the same mechanism in another chamber. Some reciprocating air compressors are air cooled, while others use water; some are lubricated while others are not, and so on and so forth. The variation is extremely wide.

Since rotary screw compressors are generally less expensive, they have taken over a large portion of the market that was once the exclusive domain of the reciprocal compressor, especially the 100 to150 pounds per square inch (psig) range with engines operating above thirty horsepower. However, in older factories and especially in older petroleum applications, one will frequently see the two-stage reciprocal air compressors pumping away. The main reasons that they have fallen out of favor are because (a) they are more expensive to buy and maintain; (b) they are much louder; and (c) the large units need a firm concrete foundation.

Despite the fact that many of these complaints are legitimate, they are also dual-sided: (a) while they are more expensive to buy and maintain, they last between two and six times longer than most rotary screw compressors; (b) while they are louder, they are generally more efficient, especially when dealing with non-continuous use, gasses other than air, or in trying climates; and (c), though they require a heavy foundation, they last so long this is a justified expense as long as you do not intend to move the unit very often. The reality is, the technology and material improvements are gradually eliminating most of the key differences between the two types of air compressor today.

Of course all of this only deals with the very large units. For the smaller ones, like those found in many automotive shops, the reciprocal air compressor has the supreme advantage of working just as efficiently with either continuous or intermittent operation. This is something that no rotary screw compressor can really compete with. As a proven technology with a dependable track record, the reciprocal air compressor is not going anywhere or going to be replaced, and as the technology evolves and the materials improve, the differences between reciprocal and rotary screw air compressors will continue to narrow. In the end, the only core difference will probably be the efficiency levels with intermittent use, which will likely always be an advantage for the traditional reciprocal air compressor.

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