A trompe is a water-powered gas compressor
Gas compressor
A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume.Compressors are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe. As gases are compressible, the compressor also reduces the volume of a gas...

, commonly used before the advent of the electric-powered compressor. A trompe is somewhat like an airlift pump
Airlift pump
An airlift pump is a simple pump which is powered by compressed air.-Principle:The only energy required is air.This air is usually compressed by a compressor or a blower....

 working in reverse.

Trompes were used to provide compressed air for bloomery
A bloomery is a type of furnace once widely used for smelting iron from its oxides. The bloomery was the earliest form of smelter capable of smelting iron. A bloomery's product is a porous mass of iron and slag called a bloom. This mix of slag and iron in the bloom is termed sponge iron, which...

 furnaces in Catalonia
Catalonia is an autonomous community in northeastern Spain, with the official status of a "nationality" of Spain. Catalonia comprises four provinces: Barcelona, Girona, Lleida, and Tarragona. Its capital and largest city is Barcelona. Catalonia covers an area of 32,114 km² and has an...

 and the USA. The presence of a trompe is a signature attribute of a Catalan forge, a type of bloomery furnace.

In Paris
Paris is the capital and largest city in France, situated on the river Seine, in northern France, at the heart of the Île-de-France region...

 they were used for a time to compress air to drive the city's first electricity generation scheme, and in the Alps
The Alps is one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east through Italy, Switzerland, Liechtenstein and Germany to France in the west....

 they were used in France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

 and Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....

 to provide compressed air for early alpine tunnels.

Trompes can be enormous. At Canadian Hydro Developers
Canadian Hydro Developers
Canadian Hydro Developers, Inc. was a Canadian company that operated 12 hydroelectric power sites, eight wind power sites and one biomass power site in Canada....

' Ragged Chute facility in New Liskeard, Ontario
Ontario is a province of Canada, located in east-central Canada. It is Canada's most populous province and second largest in total area. It is home to the nation's most populous city, Toronto, and the nation's capital, Ottawa....

, water falls down a shaft 351 feet (107 m) deep and 9 ft (2.7 m) across to generate compressed air for mining equipment and ventilation.


Trompes are very simple devices. A vertical pipe or shaft goes down to a separation chamber, a pipe coming away from that chamber allows the water to exit at a lower level, and another pipe coming from the chamber allows the compressed air
Compressed air
Compressed air is air which is kept under a certain pressure, usually greater than that of the atmosphere. In Europe, 10 percent of all electricity used by industry is used to produce compressed air, amounting to 80 terawatt hours consumption per year....

 to exit as needed.

Water rushing down the vertical pipe falls through a constriction.
The constriction produces a lower pressure because of the venturi effect
Venturi effect
The Venturi effect is the reduction in fluid pressure that results when a fluid flows through a constricted section of pipe. The Venturi effect is named after Giovanni Battista Venturi , an Italian physicist.-Background:...

, and an external port allows air to be sucked in.
The air forms bubbles in the pipe.
As the bubbles go down the pipe they are pressurized proportionally to the hydraulic head
Hydraulic head
Hydraulic head or piezometric head is a specific measurement of water pressure above a geodetic datum. It is usually measured as a water surface elevation, expressed in units of length, at the entrance of a piezometer...

, which is the height of the column of water in the pipe.
The compressed air rises to the top of the separation chamber.
The separation chamber has a compressed-air takeoff pipe, and the compressed air can be used as a power source.

The energy of the falling water entrains the air into the water, but that is not the energy that pressurizes the air, as is often incorrectly claimed. That energy is solely a derivative of the hydraulic head.

Large trompes were often situated at high waterfall
A waterfall is a place where flowing water rapidly drops in elevation as it flows over a steep region or a cliff.-Formation:Waterfalls are commonly formed when a river is young. At these times the channel is often narrow and deep. When the river courses over resistant bedrock, erosion happens...

s so that plenty of power was available.
The Ragged Chute plant on the Montreal River
Montreal River (Timiskaming District, Ontario)
The Montreal River is a river in Timiskaming District, Ontario, Canada. It travels from its source at Smoothwater Lake to its mouth at Lake Timiskaming on the Ottawa River. The river is a significant source of hydroelectricity.-Course:...

 near the town of Cobalt, Ontario
Cobalt, Ontario
Cobalt is a town in the district of Timiskaming, province of Ontario, Canada, with a population of 1,223 In 2001 Cobalt was named "Ontario's Most Historic Town" by a panel of judges on the TV Ontario program Studio 2, and in 2002 the area was designated a National Historic Site.-History:Silver was...

, is a trompe and tourist attraction. It is now owned by Canadian Hydro
Canadian Hydro Developers
Canadian Hydro Developers, Inc. was a Canadian company that operated 12 hydroelectric power sites, eight wind power sites and one biomass power site in Canada....

 and exists beside a modern hydroelectric plant.

External links

  • Farga Rossell a catalan furnace in Andorra
    Andorra , officially the Principality of Andorra , also called the Principality of the Valleys of Andorra, , is a small landlocked country in southwestern Europe, located in the eastern Pyrenees mountains and bordered by Spain and France. It is the sixth smallest nation in Europe having an area of...

     (retrieved April 2, 2011)
  • Article in Mother Earth News
    Mother Earth News
    Mother Earth News is a bi-monthly American magazine that has a circulation of 475,000. It is based in Topeka, Kansas.Approaching environmental problems from a down-to-earth, practical, how-to standpoint, Mother Earth News has, since the magazine’s founding in 1970, been a pioneer in the promotion...

    (retrieved October 15, 2011)
  • Ragged Chutes in Cobalt Ontario. Uses a 17-meter head. (previously retrieved August 27, 2009, as of May 19, 2010 no longer has technical details of the chute)
  • Cobalt Mining Legacy Ragged Chutes technical details (retrieved August 6, 2010)
  • C. H. Taylor pioneer hydraulic compressor designer including Ragged Chutes in Cobalt Ontario (retrieved August 6, 2010)
  • Illustrated Book by C.H. Taylor: Taylor Hydraulic Air Compressor (1897) (retrieved October 16, 2011)
  • Trompe Catalan Furnace in San Juan Capistrano, California
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