Compressed Air

Compressed air is air kept at a pressure greater than atmospheric pressure, used as an important medium for transferring energy in industrial processes, powering tools such as air hammers, drills and wrenches, atomizing paint, operating air cylinders for automation, and propelling vehicles. Industrial use of piped compressed air for power transmission developed in the mid-nineteenth century, since unlike steam it could be piped long distances without losing pressure to condensation, an early major application being the drilling of the Mont Cenis Tunnel in 1861. Compressed air is also used as a breathing gas by underwater divers and by firefighters and rescue workers in hazardous atmospheres, and compressed air brakes, developed by George Westinghouse from 1869, considerably improved the safety of rail operations. In Europe, producing compressed air accounts for about ten percent of all industrial electricity consumption.