The Bunsen lamp - also known as the Bunsen burner - is a burner. Found in all chemical laboratories, it is fuelled by gas to heat substances collected to carry out reactions. It is now a disused system because the open flame is unsafe. But in many laboratories it is still used. As an alternative, electric heaters are used, which are safer. In certain cases, it is mandatory to use electric heating because there must be no traces of combustion, which are detected with flame heating.
Bunsen lamp safety
Although superseded by other technologies, the Bunsen lamp is still designed to ensure a certain degree of safety. In fact, the burner is fitted with a valve that prevents the gas from flowing back into the tube and thus to the cylinder. It burns natural gas in a continuous flow, mainly methane with traces of propane and butane. Liquid petroleum gas is also sometimes used.
How the Bunsen burner is made
The Bunsen burner has a base and a tube at the end of which the gas is accessed. A pipe is connected to the base of the tube, from which the gas arrives at the end of the tube near a nozzle. The tube contains two holes to let air into it. The tube is covered by a sleeve that also has two holes. By rotating the sleeve, the holes can be matched to allow air to enter. By rotating the sleeve by different degrees, different amounts of air can be drawn in. This is sucked in by Venturi's law.
The presence of different amounts of air makes it possible to obtain a flame of a different nature. When the flame is blue it is oxidising. When the flame is orange it is reducing. This is also the case with the open flame when the appliance is not in use. A screw also allows the gas flow rate to be modulated.
Various processes in the laboratory are carried out with the flame. Some substances even have to be heated to over 1400 °C. The curious aspect of Bunsen lamps is that they were not invented by the German chemist and physicist after whom they are named. The refinement of the design was instead carried out by his assistant Peter Desaga, who completed an earlier work by Michael Faraday.