A bellows or pair of bellows is a device constructed to furnish a strong blast of

air An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...

. The simplest type consists of a flexible bag comprising a pair of rigid boards with handles joined by flexible leather sides enclosing an approximately airtight cavity which can be expanded and contracted by operating the handles, and fitted with a

valve A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or Slurry, slurries) by opening, closing, or partially obstructing various passageways. Valves are technically Pip ...

allowing air to fill the cavity when expanded, and with a tube through which the air is forced out in a stream when the cavity is compressed. It has many applications, in particular blowing on a fire to supply it with air. English Bellows

The term "bellows" is used by extension for a flexible bag whose volume can be changed by compression or expansion, but not used to deliver air. For example, the light-tight (but not airtight) bag allowing the distance between the

lens A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements'') ...

and

film A film, also known as a movie or motion picture, is a work of visual art that simulates experiences and otherwise communicates ideas, stories, perceptions, emotions, or atmosphere through the use of moving images that are generally, sinc ...

of a folding photographic camera to be varied is called a

bellows A bellows or pair of bellows is a device constructed to furnish a strong blast of air. The simplest type consists of a flexible bag comprising a pair of rigid boards with handles joined by flexible leather sides enclosing an approximately airtig ...

Etymology

Remscheid - Deutsches Werkzeugmuseum 06 ies

"Bellows" is only used in plural. The

Old English Old English ( or , or ), or Anglo-Saxon, is the earliest recorded form of the English language, spoken in England and southern and eastern Scotland in the Early Middle Ages. It developed from the languages brought to Great Britain by Anglo-S ...

name for "bellows" was , 'blast-bag', 'blowing-bag'; the prefix was dropped and by the eleventh century the simple , , ('bag') was used. The word is

cognate In historical linguistics, cognates or lexical cognates are sets of words that have been inherited in direct descent from an etymological ancestor in a common parent language. Because language change can have radical effects on both the s ...

with " belly". There are similar words in

Old Norse Old Norse, also referred to as Old Nordic or Old Scandinavian, was a stage of development of North Germanic languages, North Germanic dialects before their final divergence into separate Nordic languages. Old Norse was spoken by inhabitants ...

, Swedish, and Danish and Dutch (blaasbalg), but the derivation is not certain. 'Bellows' appears not to be cognate with the apparently similar Latin .

Metallurgy

Several processes, such as metallurgical iron

smelting Smelting is a process of applying heat and a chemical reducing agent to an ore to extract a desired base metal product. It is a form of extractive metallurgy that is used to obtain many metals such as iron-making, iron, copper extraction, copper ...

and

welding Welding is a fabrication (metal), fabrication process that joins materials, usually metals or thermoplastics, primarily by using high temperature to melting, melt the parts together and allow them to cool, causing Fusion welding, fusion. Co ...

, require so much heat that they could only be developed after the invention, in antiquity, of the bellows. The bellows are used to deliver additional air to the fuel, raising the rate of combustion and therefore the heat output. Various kinds of bellows are used in

metallurgy Metallurgy is a domain of materials science and engineering that studies the physical and chemical behavior of metallic elements, their inter-metallic compounds, and their mixtures, which are known as alloys. Metallurgy encompasses both the ...

: * Box bellows were and are traditionally used in East Asia. * Pot bellows were used in ancient Egypt. * Tatara foot bellows from Japan. *

Accordion Accordions (from 19th-century German language, German ', from '—"musical chord, concord of sounds") are a family of box-shaped musical instruments of the bellows-driven free reed aerophone type (producing sound as air flows past a Reed (mou ...

bellows, with the characteristic pleated sides, have been used in Europe for many centuries. * Piston bellows developed in Southeast Asia (probably by the

Austronesian peoples The Austronesian people, sometimes referred to as Austronesian-speaking peoples, are a large group of peoples who have settled in Taiwan, maritime Southeast Asia, parts of mainland Southeast Asia, Micronesia, coastal New Guinea, Island Melan ...

) using the principles of the similarly indigenous fire piston. It led to the independent development of

bronze Bronze is an alloy consisting primarily of copper, commonly with about 12–12.5% tin and often with the addition of other metals (including aluminium, manganese, nickel, or zinc) and sometimes non-metals (such as phosphorus) or metalloid ...

and

iron Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's o ...

metallurgy in

Southeast Asia Southeast Asia is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Mainland Au ...

. They were present in various Southeast Asian cultures, and the technology was transported to

Madagascar Madagascar, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, f ...

via the

Austronesian expansion The Austronesian people, sometimes referred to as Austronesian-speaking peoples, are a large group of peoples who have settled in Taiwan, maritime Southeast Asia, parts of mainland Southeast Asia, Micronesia, coastal New Guinea, Island Melanesi ...

. :*The technology was later adopted and refined by the Han Chinese into the double-action piston bellows, replacing the native Chinese ox hide pot or drum bellows completely. :* Piston bellows were independently developed in the middle of the 18th century in Europe. * Metal bellows were made to absorb axial movement in a dynamic condition. Often referred to as Axial Dynamics bellows types. Chinese bellows were originally made of ox hide with two pots as described in

Mozi Mozi, personal name Mo Di, was a Chinese philosopher, logician, and founder of the Mohist school of thought, making him one of the most important figures of the Warring States period (221 BCE). Alongside Confucianism, Mohism became the ...

's book on military technology in the

Warring States period The Warring States period in history of China, Chinese history (221 BC) comprises the final two and a half centuries of the Zhou dynasty (256 BC), which were characterized by frequent warfare, bureaucratic and military reforms, and ...

(4th century BC). By the

Han dynasty The Han dynasty was an Dynasties of China, imperial dynasty of China (202 BC9 AD, 25–220 AD) established by Liu Bang and ruled by the House of Liu. The dynasty was preceded by the short-lived Qin dynasty (221–206 BC ...

, contact with Southeast Asian cultures exposed the Chinese to the bamboo-based piston bellows of Southeast Asians. The acquired piston bellows technology completely replaced the Chinese ox hide bellows that by the

Song dynasty The Song dynasty ( ) was an Dynasties of China, imperial dynasty of China that ruled from 960 to 1279. The dynasty was founded by Emperor Taizu of Song, who usurped the throne of the Later Zhou dynasty and went on to conquer the rest of the Fiv ...

, the ox hide bellows were completely extinct. The

Chinese mechanical engineer

Du Shi Du Shi (, d. 38'' Book of Later Han'', vol. 31Crespigny, 183.) was a Chinese hydrologist, inventor, mechanical engineer, metallurgist, and politician of the Eastern Han dynasty. Du Shi is credited with being the first to apply hydraulic power ...

(d. 38) is credited with being the first to use hydraulic power on a double-action piston pumps, through a waterwheel, to operate bellows in metallurgy. His invention was used to operate piston bellows of blast furnaces in order to forge

cast iron Cast iron is a class of iron–carbon alloys with a carbon content of more than 2% and silicon content around 1–3%. Its usefulness derives from its relatively low melting temperature. The alloying elements determine the form in which its car ...

. The

ancient Greeks Ancient Greece () was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity (), that comprised a loose collection of culturally and linguistically re ...

ancient Romans The Roman people was the ethnicity and the body of Roman citizenship, Roman citizens (; ) during the Roman Kingdom, the Roman Republic, and the Roman Empire. This concept underwent considerable changes throughout the long history of the Roman ...

, and other civilizations used bellows in

bloomery A bloomery is a type of metallurgical furnace once used widely for smelting iron from its iron oxides, oxides. The bloomery was the earliest form of smelter capable of smelting iron. Bloomeries produce a porous mass of iron and slag called ...

furnaces producing

wrought iron Wrought iron is an iron alloy with a very low carbon content (less than 0.05%) in contrast to that of cast iron (2.1% to 4.5%), or 0.25 for low carbon "mild" steel. Wrought iron is manufactured by heating and melting high carbon cast iron in an ...

. Bellows are also used to send pressurized air in a controlled manner in a fired heater. In modern industry, reciprocating bellows are usually replaced with motorized blowers.

Double-acting piston bellows

Double-acting piston bellows are a type of bellows used by

blacksmith A blacksmith is a metalsmith who creates objects primarily from wrought iron or steel, but sometimes from #Other metals, other metals, by forging the metal, using tools to hammer, bend, and cut (cf. tinsmith). Blacksmiths produce objects such ...

s and

smelter Smelting is a process of applying heat and a chemical reducing agent to an ore to extract a desired base metal product. It is a form of extractive metallurgy that is used to obtain many metals such as iron, copper, silver, tin, lead and zin ...

s to increase the air flow going into the forge, with the property that air is blown out on both strokes of the handle (in contrast to simpler and more common bellows that blow air when the stroke is in one direction and refill the bellows in the other direction). These bellows blow a more constant, and thus stronger, blast than simple bellows.Craddock, Paul T. ''Early Metal Mining and Production''. pp. 183-4. Such bellows existed in

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

at least since the 5th century BC, when it was invented, and had reached Europe by the 16th century. In 240 BC, The ancient Greek inventor Ctesibius of Alexandria independently invented a double-action piston bellow used to lift water from one level to another. A piston is enclosed in a rectangular box with a handle coming out one side. The

piston A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder (engine), cylinder a ...

edges are covered with feathers, fur, or soft paper to ensure that it is airtight and lubricated. As the piston is pulled, air enters from the far side and the air in the near chamber is compressed and forced into a side chamber, where it flows through the nozzle. Then as it is pushed air enters from the near side and the air in the far chamber flows through the same nozzle.

Double-lung accordion bellows

These have three leaves. The middle leaf is fixed in place. The bottom leaf is moved up and down. The top leaf can move freely and has a weight on it. The bottom and the middle leaves contain valves, the top one does not. Only the top lung is connected to the spout. When the bottom leaf is moved up, air is pumped from the bottom lung into the top lung. At the same time air is leaving the bellows from the top lung through the spout, but at a slower rate. This inflates the top lung. Next the bottom leaf is moved down to pull fresh air into the bellows. While this happens the weight on the top leaf pushes it down, so air keeps leaving through the spout. This design does not increase the amount of air flow going into the forge, but provides a more constant air flow compared to a simple bellows. It also provides more even air flow than two simple bellows pumped alternately or one double-acting piston bellows.

Primitive bellows

In archaeological ruins of the

Levant The Levant ( ) is the subregion that borders the Eastern Mediterranean, Eastern Mediterranean sea to the west, and forms the core of West Asia and the political term, Middle East, ''Middle East''. In its narrowest sense, which is in use toda ...

, archaeologists have found primitive pot bellows, consisting of a ceramic pot to which a loose leather hide had been attached at the top. Such pot bellows were constructed with a wide rim, so that the hide covering would transmit a maximum amount of air when pumped. The covering was fastened to the pot with a cord under an out-turned rim, or in a groove just below the rim exterior. An opening near the base served to insert a pipe of perishable material whose purpose was to direct the air blast to either the furnace or crucible, and which was usually done through the mediation of a tuyère. Tuyères used in conjunction with pot bellows had the function of protecting the ends of perishable tubes leading from the pot into the fire. Places in Saharan Africa still make use of primitive pot bellows.

Further applications

Fluid transfer applications

*Bellows are used extensively in hydraulic power circuits and cooling loops. *They are an essential part of anesthesia machines. *

Cuckoo clock A cuckoo clock is a type of clock, typically pendulum clock, pendulum driven, that striking clock, strikes the hours with a sound like a common cuckoo call and has an automated cuckoo bird that moves with each note. Some move their wings and ope ...

s use bellows to blow air through their gedackt (pipes) and imitate the call of the Common Cuckoo bird. *

Musical instrument A musical instrument is a device created or adapted to make Music, musical sounds. In principle, any object that produces sound can be considered a musical instrument—it is through purpose that the object becomes a musical instrument. A person ...

s may employ bellows as a substitute or regulator for air pressure provided by the human

lung The lungs are the primary Organ (biology), organs of the respiratory system in many animals, including humans. In mammals and most other tetrapods, two lungs are located near the Vertebral column, backbone on either side of the heart. Their ...

s: **

, concertina and related instruments ** Reed organ **

Pipe organ The pipe organ is a musical instrument that produces sound by driving pressurised air (called ''wind'') through the organ pipes selected from a Musical keyboard, keyboard. Because each pipe produces a single tone and pitch, the pipes are provide ...

** Musette de cour,

Uilleann Pipes The uilleann pipes ( or , ), also known as Union pipes and sometimes called Irish pipes, are the characteristic national bagpipe of Ireland. Their current name is a partial translation of the Irish language terms (literally, "pipes of the ...

and some other varieties of

bagpipes Bagpipes are a woodwind instrument using enclosed reeds fed from a constant reservoir of air in the form of a bag. The Great Highland bagpipes are well known, but people have played bagpipes for centuries throughout large parts of Europe, N ...

Harmonium The pump organ or reed organ is a type of organ that uses free reeds to generate sound, with air passing over vibrating thin metal strips mounted in a frame. Types include the pressure-based harmonium, the suction reed organ (which employs a va ...

and melodeon **

Portative A portative organ (from the Latin verb , "to carry"), also known during Italian Trecento as the , is a small pipe organ that consists of one rank of flue pipes, sometimes arranged in two rows, to be played while strapped to the performer at a r ...

Expansion joint applications

The term "bellows" is used by extension for a number of applications that do not involve air transfer. *Bellows are widely used in industrial and mechanical applications such as rod boots, machinery way covers, lift covers and rail covers to protect rods, bearings and seals from dirt. *Bellows are widely used on articulated buses and

trams A tram (also known as a streetcar or trolley in Canada and the United States) is an urban rail transit in which Rolling stock, vehicles, whether individual railcars or multiple-unit trains, run on tramway tracks on urban public streets; some ...

, to cover the joint where the vehicle bends. *Bellows are used in mechanical aneroids by acting as a precision indicator of pressure levels based on their lateral movement. *Bellows tubing, a type of lightweight, flexible, extensible tubing may be used for delivery of gas or air at near-ambient pressure, as in early aqua-lung designs. * Folding and

view camera A view camera is a large format, large-format camera in which the large format lens, lens forms an erect image, inverted image on a ground glass, ground-glass screen directly at the film plane. The image is viewed, composed, and focused, then the ...

s use bellows to exclude light while allowing the lens to be moved relative to the film plane for focusing and, mainly in view cameras, to allow the lens to slide and tilt to control the image ( camera movements). *Piping

expansion joint A expansion joint, or movement joint, is an assembly designed to hold parts together while safely absorbing temperature-induced expansion and contraction of building materials. They are commonly found between sections of buildings, bridges, s ...

: In this application, bellows are formed in series to absorb thermal movement and vibration in piping systems that transport high temperature media such as exhaust gases or steam.

Beekeeping

Bee smokers have bellows attached to the side to provide air to a slow burning fuel. This allows for an increased rate of combustion and a temporarily higher output of smoke on command, something desirable when calming domesticated bees.

Gallery

File:Sealed urethane bellows.JPG, Urethane bellows Image:Blowing_Smoke.jpg, A large bellows creates a mushroom cloud at the

Exploratorium The Exploratorium is a museum of science museum, science, technology museum, technology, and art museum, arts in San Francisco, California. Founded by physicist and educator Frank Oppenheimer in 1969, the museum was originally located in the ...

San Francisco, California San Francisco, officially the City and County of San Francisco, is a commercial, Financial District, San Francisco, financial, and Culture of San Francisco, cultural center of Northern California. With a population of 827,526 residents as of ...

References

Notes

Bibliography

* *

External links

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