A pneumatic circuit is an interconnected set of components that convert compressed gas (usually air) into mechanical work. In the normal sense of the term, the circuit must include a compressor or compressor-fed tank.Active componentsCompressorTransmission linesAir tankPneumatic hosesOpen atmosphere (for returning the spent gas to the compressor)ValvesPassive componentsPneumatic cylindersThe following devices operate using compressed gases, but are not normally thought of as being pneumatic circuits:GunsRocketsRefrigeratorsInternal combustion enginesScuba sets See more at Wikipedia.org...