Bunsen burner is a gas burner that produces smokeless, nonluminous flame used for heating, sterilizing, and combustion purposes in laboratory experiments. It was named after Robert Bunsen, a German scientist who designed it in 1857. A.D.
Bunsen burner ignites by the fusion of fuel and air (oxygen). There are two primary fuel sources for bunsen burner: natural gas (methane) and liquified petroleum gas (propane, butane, or a mixture of both).
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The Bunsen burner is an essential part of laboratory equipment used for heating materials in the laboratory. It consists of seven major components: the base, barrel (chimney), air regulator (collar), air holes, gas valve, gas nozzle, and gas intake tube.
Base: It is a wide and weighty part, present in the bottom of the Bunsen burner, available in variable shapes. It helps to provide support to the burner. It also helps to provide direct contact of the burner with the work surface.
Barrel: It is also known as a chimney. It is a 5 inches long metal tube that rests on the base of the burner. It consists of two holes near the bottom end, known as an air intake opening that allows passage of air into the barrel. When natural gas passes through the air intake opening, the gas and air mixture ignites at its upper end.
The air regulator (collar): It is a short metallic cylindrical structure around the air holes at the bottom end of the barrel. The primary function of the collar is to control the amount of air entering the barrel. It works on the screw mechanism; a clockwise turn increases air intake, whereas anticlockwise rotation decreases air intake.
Air holes: Two air holes are present near the bottom end of the barrel. It allows air to enter the burner to make a mixture of air or any other liquid fluid and gas.
Gas valve: It is connected internally with the gas nozzle, the gas receiving part. The gas supply to the burner can be controlled by rotating the gas valve right or left.
Gas nozzle: A plastic or rubber pipe is connected to the gas source. It helps to allow natural gas to enter the burner.
Gas intake tube: Ruber tubes transfer gas into a bunsen burner.
Bunsen burner is generally fitted with spiky fittings at the base of the barrel that helps to connect the rubber tube, which is responsible for feeding gas to the burner. The gas passing through the rubber tube goes up the barrel from the bottom of the burner.
The principle of the bunsen burner is based on its ability to mix gases with oxygen by venturi effect before the mixture is ignited. The venturi effect states that the pressure decreases due to an increase in the velocity of the fluid that flows through the constricted pipe or hole. Likewise, in the case of a bunsen burner, gas flowing through the chimney has low pressure than the steady air surrounding it. This variation in pressure causes air to be drawn into the air hole as the gas flowing passes through it with the help of the venturi effect. As a result, the flame burning at the top of the barrel occurs on the mixing of gas and oxygen.
Thus, the amount of air supplied, which can be regulated by the collar (adjustable valve), is directly proportional to the strength and color of the flame. With a closed valve, a minimal amount of air (oxygen) passes, and a smoky yellow (low temperature) flame is produced. Whereas, with opened valve, a sufficient amount of air enters, and the roaring flame is produced hot, nearly colorless.
Generally, the flame produced by the burner can be controlled by two factors; fuel to air ratio
and amount of energy.
Fuel-to-air ratio: It determines the intensity and type of flame produced. The amount of air is controlled by an air valve.
Amount of fuel: The amount of fuel is controlled by a gas valve.
Based on the above two factors, the burner produces different flames. These include; safety flame, medium flame, and roaring flame.
There are different types of Bunsen burners to choose from, depending on the gas source and experimental conditions, which include; the tirrill burner, teclu burner, and meker burner.
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