Bunsen
burner is a very common heating device widely used in chemistry laboratories
for heating substances for different experiments. Bunsen burner provides a
hot, steady, and smokeless flame. It is a small gas burner with the function
of an adjustable flame. The amount of gas and air admitted into the burner
is controlled from the base. Bunsen burner produces a single open flame that
is used for combustion, heating, and sterilization.
Design of Bunsen Burner
A
Bunsen burner is made of the following components. It includes a vertical
metal tube that is connected to a weighted base. The base has a nozzle,
which connects with a fuel source, a gas valve. It has flow adjuster to
control how much air is admitted through small air holes at the base of the
tube. The fuel mixes with air at the bottom of the tube and rises to the top
of the Bunsen burner where it is lit with a match.
- Fuel Source : The Bunsen burner safely burns a continuous
stream of any flammable gas such as natural gas (principally methane) or
a liquefied petroleum gas like butane or propane or a mixture of both.
When it was invented, it would have mostly burnt coal gas.
- Base & Barrel : The burner possess a heavy base so that
it may stand firmly on an even surface. The base is provided with a
vertical tube (barrel) and a connector for a gas line (hose barb). The
hose barb connects the gas nozzle on the lab bench with rubber tubing.
Most of the lab benches are attached with several gas nozzles connected
to a central gas source, nitrogen, vacuum, and steam nozzles. The gas
passes through the base through a small hole at the bottom of the barrel
and flow upward. The open air slots provided in the side of the tube
bottom allows air to enter the stream via the Venturi effect. Once the
gas reaches the top of the barrel it is ignited by a flame or spark.
- Air Hole : The completeness of the combustion reaction is
affected by the amount of air mixed with the gas stream. Lesser amount
of air results in an incomplete and cooler reaction. Whereas fuel stream
well mixed with air provides oxygen in an equimolar amount and thus
complete combustion is obtained. The air flow is controlled by opening
or closing the slot openings at the base of the barrel.
History of Burners
Robert Bunsen (1811-1899)
 Robert
Wilhelm Eberhard Bunsen, a German chemist and physicist, is known for
his work in inorganic chemistry. He invented the burner in 1855, which
was named after him. Bunsen invented or improved on the electrochemical
battery (Bunsen battery), the spectroscope, and the photometer. He was
one of the founders of the field of spectroscopy. |
Heating is required for a number of chemical reactions in chemistry
laboratories ans so the burners. Whether changing sand into glass,
transforming dull rock into gleaming metal or separating mixtures into
intoxicating vapors, a hot flame has always played a starring role in the
laboratory. Heating was a problem for all chemists well into the 19th
century. Charcoal burners and furnaces were used for calcinations but
delicate experiments like distillation demanded something more subtle. The
oil-based heaters had the problem of sootiness of the flame, which blackened
the flasks and reduced the amount of heat the lamp could deliver. Spirit
lamp was a better option. The amount of alcohol in the spirit was crucial.
As pure ethanol burns with a luminous, sooty flame, so adding water reduced
the soot but also the combustion temperature. In 1855, an efficient burner
was invented by Mr. Robert Bunsen and his assistant, which was named as
Bunsen burner.
Safety Guidelines for Using
Bunsen Burner
While using Bunsen burners there are always the chances of fire hazards.
These burners burn at a high temperature and produce an open flame. It is
very important to follow certain guidelines for the safety and convenience
of all lab personnel.
- All combustible materials, papers, notebooks and excess chemicals
should be removed from the surrounding.
- The Bunsen burner should be placed away from any overhead equipment,
light fixtures or shelving.
- Inspect the hose for holes, pinched points, cracks, or any other
defect and ensure that the hose fits securely on the gas valve and the
Bunsen burner.
- Loose clothing, long hairs or dangling jeweleries should be tied at
the time of using the burner.
- The hoses having any defect must be replaced before using.
- All other lab personnel should be notified that the burner will be in
use.
- The open burners should not be unattended. Never leave the laboratory
putting the burner on.
- Always shut off the gas supply when its use is done.
