LABORATORY HEATING INSTRUMENTS
In a chemical laboratory, various heating devices are used:
alcohol and gas burners, electric furnaces, baths, muffle furnaces, bulb heaters, etc.
Alcohol burners are usually glass with a ground cap.
. Denatured alcohol is poured into them and supplied with a wick of untwisted threads. Alcohol burners give a not very hot flame
Fig. 8. Alcohol burner:
2 - tube with a disk,
3 - wick, 4 - cap
An alcohol burner is ignited by a burning match or torch. You can not light it from another burning spirit lamp. In the laboratory, it is forbidden to carry the alcohol burner in a lit state. To control the flame size, it is necessary to extinguish the burner and increase
or reduce the length of the outside of the wick.
After the work is completed, the burner is closed with a cap so that the alcohol does not evaporate.
When conducting experiments and syntheses in a chemical laboratory are used
gas burners Teklu, Bunsen and soldering torches.
Bunsen burner. The Bunsen burner arrangement is shown schematically in
fig. 9, b. The Bunsen burner consists of a stand on which there is a side
branch for connection to a gas valve (1), tubes with a through hole
at the bottom (6) of a rotating coupling with an opening (5) that is put on the tube and
serves to regulate the flow of air.
Fig. 9. Gas burners: a) - Teklu burner, b) - Bunsen burner, c) soldering
burner, d) - burner with dovetail nozzle, e) - flame structure,
1 - lateral branch, 2 - valve, 3 - disk, 4 - conical tube,
5 - rotary coupling, 6 - tube for mixing gas with air, 7 - tap
gas supply, 8 - air supply valve, 9 - recovery zone,
10 - oxidation zone
To light a Bunsen burner:
1. Turn off the air supply to the burner by turning the coupling,
2. Open the gas valve and wait 2 to 3 seconds to bring a lit match to the edge of the burner opening. Do not bend over the burner!
3. Light the gas, and then adjust the burner flame, gradually opening
through hole on the tube by turning the sleeve,
4. To turn off the burner, close the gas valve.
Teklu burner is more perfect, because its design allows
finely regulate the flow of air and gas. The Teklu burner arrangement is shown schematically in fig. 9 a. Gas enters through a side outlet (1) into a cone-shaped tube (4), where it is mixed with air. Gas supply is regulated by valve (2).
Air enters the tube through the gap between the conically-shaped base of the tube and the disk (3), mounted on a screw thread. Turning
disk, you can change the width of the slit and thereby regulate the flow of air into the burner.
To light the Teklu burner:
1. Shut off the air supply to the burner by turning the disc close to the conically-expanded base of the tube,
2. Ensure that the gas control valve is closed,
3. Open the gas valve and, after waiting 2 - 3 s, raise a lit match to the side of the burner mouth,
4. Light the gas, then adjust the gas and air supply,
5. To turn off the burner, first close the gas supply valve and then the gas valve.
Gas burners must not be used to heat flammable and combustible liquids. It is not allowed to leave the switched on gas burners unattended!
The flame of a properly burning burner is transparent and has a bluish tint.
It does not glow and does not smoke. With a lack of air, the flame turns yellow and smoky. In fig. 9, the temperature distribution inside a non-luminous flame is schematically shown.
Two main combustion zones are distinguished: a low-temperature reduction zone (internal) and a high-temperature oxidative (external zone). For better heating, heated objects should be placed in the upper high-temperature part of the flame. The inner zone of the flame has a temperature of 300 - 500 ºС. The highest temperature up to 1500 ºС is achieved in the outer zone, where the gas burns most vigorously due to the large influx of air.
When using faulty burners, ignoring ignition rules
or shutting down the burners and with a decrease in gas supply, a flame may slip into the burner. Usually, a characteristic pop is heard during a breakthrough, the flame becomes narrow, the burner tube is very hot. The type of flame and the characteristic noise of the working burner change. When a flame passes, it is necessary to immediately close the gas valve and inform laboratory assistants or a teacher. Students are not allowed to troubleshoot gas appliances on their own. To obtain a wide and flat flame, a special dovetail nozzle is put on the gas burner (Fig. 9, d).
In a laboratory workshop, sometimes a higher temperature is required than that given by alcohol or gas burners. In this case, soldering torches are used (Fig. 9, c).
Air Blow Solder Torch It is used for glass-blowing operations, as well as for calcining substances in iron crucibles. The soldering torch consists of two tubes inserted one into the other. Gas enters the outer tube through a side outlet with a tap (7), and through the inner tube with a tap
(8) - air under pressure, due to which the flame temperature rises significantly.
Special care is required when igniting a soldering torch.
To light a soldering torch:
1. Before igniting the burner, make sure that the gas and air supply taps
closed on the burner
2. Open the taps on the rack, light a match, hold it from the bottom to the mouth of the burner,
3. Carefully open the gas cock and set fire to the gas without bending over
4. Adjust the burner flame with the gas and air valves.
5. To turn off the burner, first shut off the air with a tap and then gas
tap (not vice versa) and close the gas tap.
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Gas burner device mod. 2610 (2611)
The picture on the left shows the Bunsen 2610 (2611) burner.
Refers to burners with adjustable flame characteristics. At the bottom of the burner there is a fitting for supplying gas to the burner (pos. 1) and a shut-off valve handle (pos. 2). The shut-off needle valve is used to adjust the thermal power of the burner by changing the height of the flame of the latter.
There is a stationary pilot burner for the auxiliary ignition flame (item 3). The adjustment of the height of the flame of the pilot burner is ensured by a needle adjusting device by means of a screw with a slot for a screwdriver (item 4).
The main flame tube (pos. 5) has openings (pos. 6) for air to enter it. The amount of air injected into the tube is adjusted by rotating the latter after releasing the lock nut (key 7). When the tube is rotated clockwise or counterclockwise, the holes either partially overlap or fully open.
The following are specific works for which the mod burner is used. 2610 (2611).
- heating of materials and parts,
- open flame sterilization,
- heating of small laboratory vessels (test tubes, flasks, etc.),
- other works associated with the use of high-temperature flame of small thermal power.
Ignition and extinguish the flame
1. Before using the burner for the first time without connecting it to the gas network, turn the screw (key 4) a quarter of a turn counterclockwise. Supply gas to the burner through the nozzle (key 1). Light the flame of the ignition burner (key 3). Adjust the height of the ignition burner flame with the screw (key 4). After completing work with the burner, do not change the set position of the ignition burner screw and, if you use the burner later, after supplying gas to it, ignite the flame of the ignition burner without any preliminary adjustment work with the screw (pos. 4).
2. Turn the stopcock handle to the left (key 2) to light the burner.
3. During flame burning, the torch can be resized.
- Turning the handle of the stopcock clockwise reduces the torch length.
- If you turn the handle of the stopcock counterclockwise, the length of the torch increases.
4. In order to extinguish the burner, turn the handle of the stopcock fully clockwise.
Flame color adjustment - blue or red
5. While the flame is burning, loosen the lock nut (key 7) by turning it counterclockwise by hand. Rotate the handset (key 5) clockwise if you need a blue flame or counterclockwise if you need a red flame.
6. After you finish adjusting the color of the flame, lock the tube (key 5) by turning the lock nut (key 7) fully clockwise.
- Be sure to read the operating instructions before starting the burner for the first time.
- Use indoors at a temperature of +10 to +35 degrees Celsius.
- Connect a natural gas burner (mod. 2610) to the gas network with a nominal pressure of 1.2. 1.7 kPa.
- Connect the liquefied gas burner (mod. 2611) through the gearbox to the propane tank. The working pressure of the gas (propane) must not exceed 2.2 kPa.
- Do not use the burner near flammable liquids and materials.
- Do not use a burner that has external damage or partially inoperative control levers.
- It is strictly forbidden to make any technical changes to the burner.
When working with the 2610 (2611) burner, to avoid emergency situations, you should strictly follow only this instruction. For all issues related to the operation of the burners should contact the manufacturer at the details specified below.
This manual is written
company FIRMA BST-3 LLC (www.bst-3.ru) .
Copyrigt © 2009-2013 Author F.A. Bronin.
All rights reserved.
Principle of operation
The Bunsen burner was first described in publications by Robert Bunsen in collaboration with the English chemist Henry Roscoe in 1857. In his autobiography, Roscoe argues that the burner was based on a prototype used at the Royal College of Chemistry and brought from England to Germany.