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Propane burner used with forced air into a metal melting furnace.
Propane burner used with forced air into a metal melting furnace.
Propane burner with a Bunsen flame
Propane burner with a Bunsen flame
Oxy-Acetylene for cutting through steel rails
Oxy-Acetylene for cutting through steel rails
Flame of a gas and oil, in a dual burner
Flame of a gas and oil, in a dual burner

A gas burner is a device that produces a controlled flame by mixing a fuel gas such as acetylene, natural gas, or propane with an oxidizer such as the ambient air or supplied oxygen, and allowing for ignition and combustion.

The flame is generally used for the heat, infrared radiation, or visible light it produces. Some burners, such as gas flares, dispose of unwanted or uncontainable flammable gases. Some burners are operated to produce carbon black.

The gas burner has many applications such as soldering, brazing, and welding, the latter using oxygen instead of air for producing a hotter flame, which is required for melting steel. Chemistry laboratories use natural-gas fueled Bunsen burners. In domestic and commercial settings gas burners are commonly used in gas stoves and cooktops. For melting metals with melting points of up to 1100 °C (such as copper, silver, and gold), a propane burner with a natural drag of air can be used. For higher temperatures, acetylene is commonly used in combination with oxygen.

Flame temperatures of common gases and fuels

Gas / Fuels Flame temperature
Propane in air 1980 °C 3596 °F
Butane in air 1970 °C 3578 °F
Wood in air (normally not reached in a wood stove) 1980 °C 3596 °F
Acetylene in air 2550 °C 4622 °F
Methane (natural gas) in air 1950 °C 3542 °F
Hydrogen in air 2111 °C 3831 °F
Propane with oxygen 2800 °C 5072 °F
Acetylene in oxygen 3100 °C 5612 °F
Propane-butane mix with air 1970 °C 3578 °F
Coal in air (blast furnace) 1900 °C 3452 °F
Cyanogen (C2N2) in oxygen 4525 °C 8177 °F
Dicyanoacetylene (C4N2) in oxygen (highest flame temperature) 4982 °C 9000 °F

The above data is given with the following assumptions:

Flammability limits and ignition temperatures of common gases

Flammability limit lower, in % Flammability limit upper, in % Ignition temperatures
Natural gas 4.7 15 482-632 °C
Propane 2.15 9.6 493-604 °C
Butane 1.9 8.5 482-538 °C
Acetylene 2.5 81 305 °C
Hydrogen 4 75 500 °C
Ammonia 16 25 651 °C
Carbon monoxide 12.5 74 609 °C
Ethylene 3.4 10.8 490 °C

(Atmosphere is air at 20 degrees Celsius.)

Combustion values of common gases

Gas Combustion value
(Btu/ft³) (MJ/m³)
Natural gas (methane) 950 to 1,150 35 to 43
Propane 2,572 95.8
Propane-butane mix 2,500 to 3,200 90 to 120
Butane 3,225 120.1