Compressors have been around for a lot longer than you would imagine. The earliest type of compressor was, and still is, the bellows, which consists of a leather bag with handles and an intake valve. In Roman times blacksmiths in the metal forging trade were using hydraulic compressors. These compressors operated by water rushing down a pipe and forcing air out of the bottom of the pipe and into a furnace. In the middle of the seventeenth century a German scientist named Otto von Guericke devised a compressor consisting of a single piston and cylinder with which he was able to experiment with compressed air and with vacuums.
The first truly motorised air compressor was designed and built by one George Medhurst, an Englishman, in 1799. This compressor was used in the coal mining industry. The industrial revolution brought more compressors into being when in 1852 when he designed and built a pressurised caisson. This was used by workers on the famous Brunel iron bridge in Chepstow, England, and prevented water and mud from entering their workspace. In 1857 another Englishman, Thomas Cochrane, patented a compressed air rock drill that was used extensively for tunnelling, and in the late 19th century Amedee Bollee used an air compressor to improve the performance of a hydraulic ram. Heinrich Krigar of Hannover, Germany first patented the idea of the screw compressor in March 1878, lodging a patent for an improved version of the same compressor five months later. These were among the first compressors patented but they were not developed commercially at the time because of the manufacturing capabilities of the time. Many modern versions of the rotary screw compressor are oil cooled. The first fully portable air compressor came out of the United States in the 1920s and has remained on the cutting edge of compressor technology.
Compressed air can supply a very powerful force that is difficult to produce by any other means than an air compressor. Modern compressors fall into two main categories, Dynamic and Positive Displacement. Dynamic compressors consist of either centrifugal or axial compressors, and are almost entirely found in jet engines and turbo-prop engines. The power to turn these compressors comes entirely from the engine’s own turbines. Positive displacement compressors are either reciprocating or rotary. The reciprocating engine uses a piston and is similar to a motor car engine except that the piston is driven by an external force, such as an electric motor, and it is the piston that compresses the air. Most common reciprocating compressors have either one or two pistons. Rotary compressors are one of Lobe, Liquid Ring, Screw, Scroll and Vane. They are basically enclosed fans that take in air, compress it, and blow it out again at a higher pressure. These compressors are mostly found in air conditioners and refrigerators.
Compressors are used in numerous applications today, including submarines, jet engines, turbochargers, pneumatic tools for medicine and manufacturing, pipeline transport, refrigeration, scuba diving, air conditioning, and, of course, for filling tyres!
