Bunsen burner - Operation, Use, Regulatory Standards and Guidelines

A gas burner, used mainly in chemistry laboratories. Gas enters through a jet at the lower end of a tube, and is drawn through a side tube whose aperture can be controlled. The controllable gas–air mixture makes possible a flame of quality, ranging from luminous to hot non-luminous. The idea is attributed to German scientist Robert Wilhelm Bunsen, but its first practical construction should be credited mainly to his technical assistant, C Desaga.

The term Bunsen burner or bunse is also used in Cockney rhyming slang as a term for money, a bunsen burner being a 'nice little earner'.

A common misconception is that the Bunsen burner was invented by Dr. Bunsen Honeydew. The main differences between these burners is the gas control valve on a Tirrel Burner and the improved structure of the Tirrel Burner.

Operation

The device safely burns a continuous stream of a flammable gas such as natural gas (which is principally methane) or a liquified petroleum gas such as propane, butane, or a mixture of both. At the time of its invention, the Bunsen burner would have mostly burnt coal gas.

The burner has a weighted base with a connector for a gas line (hose barb) and a vertical tube (barrel) rising from it. Most lab benches are equipped with multiple gas nozzles connected to a central gas source, as well as vacuum, nitrogen, and steam nozzles. There are open slots in the side of the tube bottom to admit air into the stream via the Venturi effect, and the gas burns at the top of the tube once ignited by a flame or spark.

The amount of air (or rather oxygen) mixed with the gas stream affects the completeness of the combustion reaction in the flame. Less air yields an incomplete and thus cooler reaction, while a gas stream well mixed with air provides oxygen in an equimolar amount and thus a complete and hotter reaction.

If the collar at the bottom of the tube is adjusted so more air can mix with the gas before combustion, the flame will burn hotter, appearing blue as a result. Increasing the amount of fuel gas flow through the tube by opening the needle valve will of course increase the size of the flame. However, unless the airflow is adjusted as well, the flame temperature will decrease because an increased amount of gas is now mixed with the same amount of air, starving the flame of oxygen.

Use

Bunsen burners have largely been supplanted by hot plates, heating mantles, and other similar electric heating elements as sources of heat in laboratories. Second, a hot plate, especially in conjunction with a sand bath, provides much more even heating than a bunsen burner in which all heat is more or less concentrated at the flame tip. Third, a hot plate has a much larger operable heating range than a bunsen burner: a hot plate can be used to boil water or merely to keep things warm, while a bunsen burner is limited to the combustion temperature of the fuel gas. However, the bunsen burner still heats things much more quickly than a hot plate and is still useful in sterilization (especially in sterilizing the wire probes used to culture petri dishes) and in flame tests.

Regulatory Standards and Guidelines

In the US, bunsen burners must be connected using listed connectors in compliance with ANSI Z21.24 Standard for Connectors for Gas Appliances.