Pneumatic tubes are systems that propel cylindrical containers through networks of tubes by compressed air or by partial vacuum. They are used for transporting solid objects, as opposed to conventional pipelines which transport fluids. In the late 19th and early 20th centuries, pneumatic tube networks gained acceptance in offices that needed to transport small, urgent packages, such as mail, other paperwork, or money, over relatively short distances, within a building or, at most, within a city. Some installations became quite complex, but have mostly been superseded. However, they have been further developed in the 21st century in places such as hospitals, to send blood samples and the like to clinical laboratories for analysis.
A pneumatic tube system in Washington, D.C. in 1943
Pneumatic tubes at a drive-through bank
NASA Mission Control Center during the Apollo 13 mission. Note pneumatic tube canisters in console to the right.
Pneumatic tube letter from Berlin, Germany, 1904
A compressor is a mechanical device that increases the pressure of a gas by reducing its volume. An air compressor is a specific type of gas compressor.
A small stationary high pressure breathing air compressor for filling scuba cylinders
High pressure reciprocating compressor from Belliss and Morcom, used in the bottling industry
A motor-driven six-cylinder reciprocating compressor that can operate with two, four or six cylinders.
A three-stage diaphragm compressor