Gas burner

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

A gas burner is a device which is used to generate a flame, in order to heat up products using a gaseous fuel such as acetylene, natural gas, or propane. Some burners have an air inlet to mix the fuel gas with air, to enable complete combustion. Acetylene is commonly used in combination with oxygen.

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. For laboratory uses, a natural-gas fueled Bunsen burner is used. 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.

Flame temperatures of common gases and fuels[edit]

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 3542 °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:

  • The flame is adiabatic
  • The surrounding air is at 20°C, 1 bar atm
  • Complete combustion (no soot, and more blue-like flame is the key) (Stoichiometric)
  • Peak Temperature
  • Speed of Combustion (has no effect on temp, but more energy released per second (as adiabatic) compared to normal flame)
  • Spectral bands also affect colour of flame, as of what part and elements of combustion
  • Blackbody radiation (colour appearance only because of heat)
  • Atmosphere - affects temperature of flame and colour due to the atmospheric colour effect

Explosive limits and ignition temperatures of common gases[edit]

Explosive limits (lower & 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

Note: Atmosphere is air at 20 degrees Celsius.

Combustion values of common gases[edit]

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

References[edit]

  • Pocket Guide to Fire and Arson Investigation, second edition, FM Global, Table 1,2 and 3