If you are in the country where there is no access to a gas main, then you have probably encountered the need to use a device of the type Quite often, people use stoves or stoves that operate from gas cylinders. alternative solution can speak homemade device, which operates on liquid fuel. If you are the owner suburban area, and periodically try to solve the problem of heating rooms and cooking, then, quite possibly, an alcohol burner will suit you. It can become an indispensable attribute even if you prefer to go to free time on overnight trips.

Main advantages of devices

The mentioned burner can easily be made by you yourself. You can take it with you to the garage, to the country house or on a hike, as well as to those places where there is no electricity, main gas or wood stoves. Using such a device, you can quickly heat water, cook food or heat a room. This invention is suitable for those places where it is impossible to make a fire, since the device produces a flame that is almost invisible, but it will be enough for cooking. An alcohol burner has many advantages, among them good performance in difficult weather conditions. And this is true even if the outside air temperature drops to -40 degrees. If you make such a device yourself, you will be able to feel how easy it is to use, compact, economical and affordable in terms of purchasing fuel. The last factor can be called one of the most important advantages of such burners, since alcohol can be purchased everywhere. Among other things, the cost of such fuel is low, especially when compared with kerosene or gas.

Burner manufacturing technology

An alcohol burner can be made in one of several ways. If you are new to this business, then you should choose the maximum simple technique, which does not involve the use of technology involves the use of two empty tin cans; they must first be cleaned and rinsed running water. After this, the products should dry well. In the central part of one of the cans, 4 punctures should be made using nails. The same holes should be made around the perimeter of the rim of the jar. This element will become a blank for the future burner, from which a flame will burst out when used.

This part must be cut off from the can so that the length of the side is equal to three centimeters. To do this, you can use household scissors, since the tin is quite thin and can be easily cut with any sharp object. When an alcohol burner is made, next stage in the second jar you need to cut off the bottom, this must be done as carefully as possible so that there are no nicks. Otherwise, you will need to use a file or sandpaper.

Methodology of work

A piece of cotton wool is placed on the bottom of the burner, which should first be moistened in alcohol. Next, the structure is covered with the upper part so that it acts as a sealed lid. If you do not ensure tight contact of the parts, then in the cracks you can install strips of tin that remain from cutting the products. When you make an alcohol burner with your own hands, it must be used according to a certain principle. Alcohol should be poured onto top part structures where holes are made. This must be done in such a way that the composition gets on the rim. The latter should also have holes. Next, the alcohol is set on fire, the tin is heated, and the heat is transferred to the cotton wool, which is soaked in alcohol. As a result, vapors begin to be released that will support the flame.

Final works

On last stage We have to make supports on which the cooking pot will be located. To do this, you should use two metal rods, which are driven in the shape of the letter P into the ground parallel to each other. During the cooking process, ensure that the device does not tip over. If you decide to make a product such as an alcohol burner with your own hands, then you should remember that such a device is disposable, since cans They won't be useful for next time.

Alternative manufacturing option

Useful homemade products may turn out to be somewhat more complex than the option described above. However, such a design will be characterized by higher reliability, durability and strength. We'll talk about it further.

Preparatory work

In order to make a device with your own hands, you should prepare a compressor; it is best to use a car tube, which you can borrow from a truck. It will need to be pumped up from time to time. An alternative solution is a compressor from an old refrigerator. You should prepare a receiver; a plastic canister with a volume of 10 liters or less is perfect for this. The cork should be solid, it is advisable to choose a translucent one. Such useful homemade products are made of several elements, among which the fuel tank should be highlighted; for this you need to use a two-liter steel container, into the lid of which two tubes are soldered. One of them should be long, the other short. The first one sinks to the bottom of the tank.

Work technology

Alcohol ones can be purchased at the store, but the design is so simple that you can make them yourself. The fuel tank should be filled with alcohol, but not more than 1/2 full. A simple filter is installed at the compressor inlet. You can do it yourself, using a funnel on which a segment is stretched. The principle of operation of the device is ensured by pumping air with a compressor, as well as its further entry into the receiver under some pressure. It smooths out pressure pulsations. The air is then sent into a container with fuel, where it is mixed with alcohol vapor. The resulting mixture goes to the burner. The combustion intensity can be adjusted using a special screw located on the burner.

Third manufacturing method

If you are wondering how to do alcohol burner, then you will need to prepare a flat metal jar, which can be a container for canned food or cosmetic cream. You will need pumice, as well as alcohol. The mechanism of such a device is extremely simple and does not require an application special effort during manufacture. To create the device, you need to pack pumice into the container as tightly as possible, and then pour a certain amount of fuel on top of everything. These manipulations must be performed as carefully as possible so that the liquid is absorbed and does not splash out. Thanks to the presence of pumice, the flame will burn for 15 minutes, since due to its porous structure it will act as a fuel distributor. Such an alcohol burner made from cans will allow you to cook food, as well as heat it sufficiently small room by type of garage or change house. To heat food, you need to build a stand for dishes, which is made of stones, wire or other material. The main thing is to take into account the requirement that the dishes need to be stable.

Main types of alcohol burners

Alcohol homemade burner may be open or closed type. Each of the above designs has its own advantages and disadvantages. If we're talking about about the device open type, then you may encounter not so high efficiency, combustion will proceed at larger area. This will promote abundant evaporation of fuel. Among other things, closed-type burners do not provide the ability to control the amount of remaining fuel. Such burners require external ignition, which increases the fire hazard. However, each of the listed burners can be made independently. It is important to remember that the operation of burners is based on the combustion of fuel mixture vapors. Therefore, it is strictly forbidden to use substances that contain acetone or gasoline as fuel.

experimental part

The capacity of the tank can be equal to 70 milliliters, the nozzles need to be made in the amount of 16 pieces, the distance between them should be one centimeter. The estimated burning time can be 25 minutes per refill. As practice shows, the duration and intensity of combustion of such devices depends on the type of fuel. The best combustion occurs from medical alcohol vapor. If we are talking about situations where salicylic acid is used, then it does not burn as intensely. If the burner is filled with edible alcohol, it will show the shortest burning time.

The temperature of the alcohol burner is high enough to heat the tent and cook food. When using alcohol devices, solutions that contain about 50-70% ethanol should be used. This allows you to extend the operating period, although it reduces the intensity of the flame. The design has the ability to boil 0.5 liters of water in 7 minutes, which is enough to brew tea or steam noodles instant cooking. During operation, do not overturn the device, as this may pose a fire hazard. As practice shows, if you throw cotton wool on top and then set it on fire, overheating can cause the alcohol to begin to evaporate greatly, causing the burner to simply break in half. The design of the burner is very simple, but before making it, many people wonder why use liquid alcohol when there is dry alcohol. The answer to this question will be higher heat transfer, which indicates the possibility of heating water faster.

Finally

Using a few, you can make your own alcohol burner, which will be able to help you out outside the city and on a camping trip on vacation. It is noteworthy that you can make such a device without additional tools. That is why it is so attractive to home craftsmen, who often prefer to relax outside the city. There is no need to take such a device with you; it will be enough to use tin cans, which can be prepared in nature. And after the first use, the device can be disposed of.

For liquid fuel, containing a reservoir for alcohol, equipped with a lid through which a wick is passed, the lower end of which is placed in the reservoir, and the upper end outside it.

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Alcohol lamp from a flashlight.

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Application

Used in tourism for cooking; in chemical and school laboratories for heating and melting materials, for heating small laboratory vessels (test tubes, flasks for chemical work, etc.) and other similar thermal processes; in medical institutions for sterilization of medical instruments in an open flame; and also wherever the use of an open flame of low thermal power is required.

Design

The container for alcohol is the main supporting part of a laboratory alcohol lamp, and its most important and main part is the wick, which transfers liquid fuel (alcohol) from the container to the end of the wick, where this fuel burns and is used for heating. The alcohol container is made in the form of a reservoir into which the lower end of the wick is lowered. The reservoir has a neck, which is equipped with a lid. The lid is necessary to separate the alcohol combustion zone from the internal volume of the tank where the liquid fuel is located. The tank cover can be placed both inside the neck and outside it, covering the latter with outside. A guide tube is usually installed in the hole in the lid through which the wick passes. The wick must be placed in the tube in such a way that, on the one hand, it can move smoothly and easily in the tube, and on the other hand, the contact of the tube with the wick must be tight enough so that the wick does not fall out of the tube. The lid of the spirit lamp may have a device for adjusting the protruding length of the wick, the recommended value of which is no more than 15 mm.

Typically, fuel for a spirit lamp is poured through the top hole of the tank after removing the lid. However, there are alcohol lamps whose tank has a side filler neck with a ground-in cap. The amount of fuel poured is determined by the internal volume of the tank. The alcohol from the reservoir rises up the wick due to capillary pressure and evaporates when it reaches the upper end of the protruding part of the wick. The alcohol vapor is ignited and the alcohol lamp burns with a flame temperature of no higher than 900° Celsius. Most alcohol lamps have a metal or glass cap, which is used both to extinguish the flame of the alcohol lamp and to prevent evaporation of the fuel.

By structural elements laboratory alcohol lamps differ from each other in the following parameters:

• tank material (metal or glass);
• tank shape (round or faceted);
• internal volume of the tank;
• wick material and thickness;
• the presence or absence of a device for regulating the protruding part of the wick;

The tank material should be selected based on the operating conditions of the alcohol lamp. If the alcohol lamp is used in conditions where it is possible that the alcohol lamp may accidentally fall onto a stone or metal floor, then from a safety point of view it is preferable to use a spirit lamp with a metal reservoir. Alcohol lamps with a glass body are much cheaper than metal ones. In addition, when operating a spirit lamp, you can always monitor the level of alcohol in the tank. However, glass is a brittle material that has little resistance to impact, and therefore there is always the possibility of destruction of the spirit lamp tank if it falls on a hard floor, which can cause a spill of burning alcohol. Therefore, in rooms with increased requirements for fire safety The use of glass spirit lamps, especially those made of thin laboratory glass, is not recommended.

The round shape of the tank is most widely used. Faceted spirit lamps are more expensive than round ones and should be used only when performing a number of specific jobs, for example, those associated with heating low-melting materials such as waxes, in order to prevent drops of heated material from getting onto the wick of the spirit lamp.

The internal volume of the alcohol lamp tank must be chosen such that during its operation, at a minimum, there would be no need to refill the alcohol lamp during one hour of its continuous operation.

Wick material and thickness important elements for the operation of an alcohol lamp. Wicks are used from cotton fabric and asbestos cord. Most widespread received wicks made of cotton fabric, as they give a more stable and even flame compared to asbestos wicks. As for the thickness of the wicks, we must proceed from the fact that the thicker the wick, the more fuel it supplies to the combustion zone. Thicker wicks also produce a larger flame with a higher flame height. As a result thermal power alcohol lamps with a thicker wick are slightly higher, but the alcohol consumption is also higher. For most laboratory work When performed using alcohol lamps, a wick thickness of at least 4.8 mm and no more than 6.4 mm is sufficient. Thicker wicks are necessary for some professional jobs that require a high, voluminous flame. It is advisable to have alcohol lamps with different thicknesses wicks and use them depending on the technological requirements for the work being performed.

A device for adjusting the size of the protruding part of the wick provides great convenience when working with alcohol lamps, since it is not necessary to extinguish the flame of the alcohol lamp each time in order to adjust the flame parameters (height and volume) by changing the size of the protruding part of the wick. Alcohol lamps with devices for adjusting the protruding part of the wick are more expensive than alcohol lamps without these devices. However, the slightly higher price is more than covered by the amenities for professional work that this device provides.

Fuel

All alcohol lamps primarily use ethyl alcohol as fuel. There are three types of ethyl alcohol on sale: rectified ethyl alcohol from food raw materials, hydrolytic technical alcohol from wood raw materials and synthetic alcohol obtained chemically. Industrial alcohol and synthetic alcohol are sometimes colored blue-violet with the addition of certain substances with a pungent odor. This alcohol is called denatured alcohol. All these types of alcohols can be used as liquid fuel for alcohol lamps.

Other types of fuel, such as isopropyl or methyl alcohol, are not recommended for use in laboratory alcohol lamps, since these alcohols have a maximum permissible concentration in the air that is two or more orders of magnitude lower than that of ethyl alcohol and is therefore hazardous to health.

Safety precautions

When working with laboratory alcohol lamps, safety rules are as follows. It is necessary to use the alcohol lamp only for the intended purpose specified in its technical passport. Do not refuel the alcohol lamp near open flame devices. Do not fill the alcohol lamp with fuel more than half the tank volume. Do not move or carry a spirit lamp with a burning wick. It is strictly forbidden to light the wick of a spirit lamp using another spirit lamp. Fill the alcohol lamp only with ethyl alcohol. Extinguish the flame of the alcohol lamp only with the cap. Do not keep flammable substances and materials that can ignite from short-term exposure to an ignition source with low thermal energy (match flame, alcohol lamp) on the workbench where an alcohol lamp is used. The room in which work with alcohol lamp(s) is carried out must be equipped with primary fire extinguishing means, for example, a powder fire extinguisher.

Advantages

• Light weight - no more than 220 g.
• Ease of use - you only need to add alcohol to the alcohol lamp tank, and then the alcohol is independently supplied to the combustion area.
• Reliability - all design elements are practically trouble-free in operation.
• Quiet operation.
• No pungent odors - the smell of ethyl alcohol before it is ignited is negligible compared to the smell of gaseous fuel in similar cases.
• Not required Maintenance- there is no need to carry out regulatory, as well as repair work for adjusting and cleaning structural elements.
• Safety at work - ethyl alcohol in small quantities is not explosive, and spilled burning alcohol can be easily extinguished using standard fire extinguishing agents (powder fire extinguishers).
• Easy to store fuel - it is possible to store ethyl alcohol in a regular plastic bottle or plastic canister.
• Low price - the cost of alcohol lamps is significantly lower than laboratory ones gas burners or other types of burners using liquid fuel (kerosene, gasoline).
• Ecologically clean fuel- does not pollute environment(safe when released into water and soil and does not form toxic substances when burned).

Flaws

• Low thermal power - the calorific value of ethyl alcohol is lower than that of other types of liquid fuel (kerosene, gasoline) and gaseous fuel (methane, propane).
• Unreliable operation low temperatures- poor evaporation of alcohol from the protruding upper part of the wick at sub-zero temperatures.
• Small mechanical strength- parts of alcohol lamps have low strength and can be deformed or destroyed even under slight mechanical stress.

During the combustion process, a flame is formed, the structure of which is determined by the reacting substances. Its structure is divided into areas depending on temperature indicators.

Definition

Flame refers to gases in hot form, in which plasma components or substances are present in solid dispersed form. Transformations of physical and chemical types are carried out in them, accompanied by glow, release of thermal energy and heating.

The presence of ionic and radical particles in a gaseous medium characterizes its electrical conductivity and special behavior in an electromagnetic field.

What are flames

This is usually the name given to processes associated with combustion. Compared to air, gas density is lower, but high temperatures cause gas to rise. This is how flames are formed, which can be long or short. Happens often smooth transition one form into another.

Flame: structure and structure

For determining appearance It is enough to ignite the described phenomenon. The non-luminous flame that appears cannot be called homogeneous. Visually, three main areas can be distinguished. By the way, studying the structure of the flame shows that various substances burn with education various types torch.

When a mixture of gas and air burns, a short flame is first formed, the color of which is blue and purple shades. The core is visible in it - green-blue, reminiscent of a cone. Let's consider this flame. Its structure is divided into three zones:

1. A preparatory area is identified in which the mixture of gas and air is heated as it exits the burner opening.
2. This is followed by the zone in which combustion occurs. It occupies the top of the cone.
3. When there is a deficiency air flow, the gas does not burn completely. Carbon divalent oxide and hydrogen residues are released. Their combustion takes place in the third region, where there is oxygen access.

Now let's look separately different processes combustion.

Burning candle

Burning a candle is similar to burning a match or lighter. And the structure of a candle flame resembles a hot gas stream, which is pulled upward due to buoyancy forces. The process begins with heating the wick, followed by evaporation of the wax.

The lowest zone, located inside and adjacent to the thread, is called the first region. It has a slight glow due to large quantity fuel, but a small volume of oxygen mixture. Here, the process of incomplete combustion of substances occurs, releasing which is subsequently oxidized.

The first zone is surrounded by a luminous second shell, which characterizes the structure of the candle flame. A larger volume of oxygen enters it, which causes the continuation of the oxidation reaction with the participation of fuel molecules. Temperatures here will be higher than in the dark zone, but not sufficient for final decomposition. It is in the first two areas that when droplets of unburned fuel and coal particles are strongly heated, a luminous effect appears.

The second zone is surrounded by a low-visibility shell with high temperature values. Many oxygen molecules enter it, which contributes to the complete combustion of fuel particles. After the oxidation of substances, the luminous effect is not observed in the third zone.

Schematic illustration

For clarity, we present to your attention an image of a burning candle. Flame circuit includes:

1. The first or dark area.
2. Second luminous zone.
3. The third transparent shell.

The candle thread does not burn, but only charring of the bent end occurs.

Burning alcohol lamp

For chemical experiments Small containers of alcohol are often used. They are called alcohol lamps. The burner wick is soaked with liquid fuel poured through the hole. This is facilitated by capillary pressure. When the free top of the wick is reached, the alcohol begins to evaporate. In the vapor state, it is ignited and burns at a temperature of no more than 900 °C.

The flame of an alcohol lamp has a normal shape, it is almost colorless, with a slight tint of blue. Its zones are not as clearly visible as those of a candle.

Named after the scientist Barthel, the beginning of the fire is located above the burner grid. This deepening of the flame leads to a decrease in the inner dark cone, and the middle section, which is considered the hottest, emerges from the hole.

Color characteristic

Various radiations are caused by electronic transitions. They are also called thermal. Thus, as a result of combustion of the hydrocarbon component in air environment, blue flame due to the release H-C connections. And with radiation particles C-C, the torch turns orange-red.

It is difficult to consider the structure of a flame, the chemistry of which includes compounds of water, carbon dioxide and carbon monoxide, and the OH bond. Its tongues are practically colorless, since the above particles, when burned, emit radiation in the ultraviolet and infrared spectrum.

The color of the flame is interconnected with temperature indicators, with the presence of ionic particles in it, which belong to a certain emission or optical spectrum. Thus, the combustion of certain elements leads to a change in the color of the fire in the burner. Differences in the color of the torch are associated with the arrangement of elements in different groups periodic system.

Fire is examined with a spectroscope for the presence of radiation in the visible spectrum. It was found that simple substances from general subgroup have a similar coloring of the flame. For clarity, sodium combustion is used as a test for this metal. When brought into the flame, the tongues turn bright yellow. Based color characteristics highlight the sodium line in the emission spectrum.

It is characterized by the property of rapid excitation of light radiation from atomic particles. When non-volatile compounds of such elements are introduced into the fire of a Bunsen burner, it becomes colored.

Spectroscopic examination shows characteristic lines in the area visible to the human eye. The speed of excitation of light radiation and the simple spectral structure are closely related to the high electropositive characteristics of these metals.

Characteristic

The flame classification is based on the following characteristics:

• aggregate state of burning compounds. They come in gaseous, airborne, solid and liquid forms;
• type of radiation, which can be colorless, luminous and colored;
• distribution speed. There is fast and slow spread;
• flame height. The structure can be short or long;
• nature of movement of reacting mixtures. There are pulsating, laminar, turbulent movement;
• visual perception. Substances burn with the release of a smoky, colored or transparent flame;
• temperature indicator. The flame can be low temperature, cold and high temperature.
• state of the fuel - oxidizing reagent phase.

Combustion occurs as a result of diffusion or pre-mixing of the active components.

Oxidative and reduction region

The oxidation process occurs in a barely noticeable zone. It is the hottest and is located at the top. In it, fuel particles are exposed complete combustion. And the presence of oxygen excess and combustible deficiency leads to an intense oxidation process. This feature should be used when heating objects over the burner. That is why the substance is immersed in the upper part of the flame. This combustion proceeds much faster.

Reduction reactions take place in the central and lower parts of the flame. It contains a large supply of flammable substances and a small amount of O 2 molecules that carry out combustion. When introduced into these areas, the O element is eliminated.

As an example of a reducing flame, the process of splitting ferrous sulfate is used. If FeSO 4 gets into central part burner torch, it is first heated, and then decomposed into ferric oxide, anhydride and sulfur dioxide. In this reaction, reduction of S with a charge of +6 to +4 is observed.

Welding flame

This type of fire is formed as a result of the combustion of a mixture of gas or liquid vapor with oxygen from clean air.

An example is the formation of an oxyacetylene flame. It distinguishes:

• core zone;
• middle recovery area;
• flare extreme zone.

This is how many gas-oxygen mixtures burn. Differences in the ratio of acetylene and oxidizing agent lead to different types flame. It can be of normal, carburizing (acetylenic) and oxidizing structure.

Theoretically, the process of incomplete combustion of acetylene in pure oxygen can be characterized by the following equation: HCCH + O 2 → H 2 + CO + CO (one mole of O 2 is required for the reaction).

The resulting molecular hydrogen and carbon monoxide react with air oxygen. The final products are water and tetravalent carbon oxide. The equation looks like this: CO + CO + H 2 + 1½O 2 → CO 2 + CO 2 +H 2 O. This reaction requires 1.5 moles of oxygen. When summing up O 2, it turns out that 2.5 moles are spent per 1 mole of HCCH. And since in practice it is difficult to find ideally pure oxygen (often it is slightly contaminated with impurities), the ratio of O 2 to HCCH will be 1.10 to 1.20.

When the oxygen to acetylene ratio is less than 1.10, a carburizing flame occurs. Its structure has an enlarged core, its outlines become blurry. Soot is released from such a fire due to a lack of oxygen molecules.

If the gas ratio is greater than 1.20, then an oxidizing flame with an excess of oxygen is obtained. Its excess molecules destroy iron atoms and other components of the steel burner. In such a flame, the nuclear part becomes short and has points.

Temperature indicators

Each fire zone of a candle or burner has its own values, determined by the supply of oxygen molecules. The temperature of the open flame in its different parts ranges from 300 °C to 1600 °C.

An example is a diffusion and laminar flame, which is formed by three shells. Its cone consists of a dark area with a temperature of up to 360 °C and a lack of oxidizing substances. Above it is a glow zone. Its temperature ranges from 550 to 850 °C, which promotes thermal decomposition of the combustible mixture and its combustion.

The outer area is barely noticeable. In it, the flame temperature reaches 1560 °C, which is due to natural characteristics fuel molecules and the speed of entry of the oxidizing agent. This is where the combustion is most energetic.

Substances ignite at different temperature conditions. Thus, magnesium metal burns only at 2210 °C. For many solids the flame temperature is around 350°C. Matches and kerosene can ignite at 800 °C, while wood can ignite from 850 °C to 950 °C.

The cigarette burns with a flame whose temperature varies from 690 to 790 °C, and in a propane-butane mixture - from 790 °C to 1960 °C. Gasoline ignites at 1350 °C. The alcohol combustion flame has a temperature of no more than 900 °C.

Safety rules when working in a chemical laboratory

1. Conduct experiments only with those substances indicated by the teacher. Do not take more substance for the experiment than is necessary.

2. Strictly follow the precautions specified by the teacher, otherwise an accident may occur.

3. Do not taste substances.

4. Take solids from jars only with a dry spoon or dry test tube. Pour liquid and pour solids carefully into the test tube. First check to see if the bottom of the test tube is broken or cracked.

5. When identifying the smell of substances, do not bring the container close to your face, as inhalation of vapors and gases can cause irritation of the respiratory tract. To get acquainted with the smell, you need to make a movement with the palm of your hand from the opening of the vessel to your nose (Fig. 115).

Rice. 115.
Familiarization with the smell of a substance

6. When heating a test tube with liquid, hold it so that its open end is directed away from both yourself and its neighbors. Perform experiments only above the table.

7. In the event of a burn, cut, or contact of caustic or hot liquids with your skin or clothing, contact your teacher or laboratory assistant immediately.

8. Do not start the experiment without knowing what and how to do.

9. Don't clutter yours workplace items that are not required to complete the experiment. Work calmly, without fuss, without disturbing your neighbors.

10. Perform experiments only in clean containers. When finished, wash the dishes. Close jars and bottles with the same stoppers or lids with which they were closed. Place the stoppers of the bottles on the table only with the end that does not go into the neck of the bottle.

11. Handle glassware, substances and laboratory supplies with care.

12. When you finish work, put your workplace in order.

Laboratory equipment

In progress practical work in a chemical laboratory they use a laboratory stand and heating devices. First familiarize yourself with their structure and the basic techniques for handling them.

1. Laboratory stand setup. The tripod (Fig. 116) serves to strengthen parts of chemical installations when performing experiments. It consists of a massive cast iron stand (2), into which a rod (2) is screwed. The massive stand gives the tripod stability. A foot (4) and a ring (5) are secured to the rod using couplings (3).

Rice. 116.
Laboratory tripod

Couplings with a claw and rings attached to them can be moved along the rod and secured in the desired position. To do this, use a screw to loosen the fastening of the coupling to the rod and, placing it at the required height, secure it.

2. Using a laboratory stand. Remove the foot and ring from the tripod installed on the table as follows. Loosen the screw securing the coupling to the rod and, lifting the coupling with the tab or ring up, remove it from the tripod rod. Then release the tab and ring from the coupling. To do this, turn the screw holding the tab and ring counterclockwise and remove them from the coupling. Consider the design of the coupling.

Place the coupling on the tripod rod so that the screw securing it is to the right of the tripod rod, and the rods of the legs or rings are strengthened in such a way that they are supported not only by the screw, but also by the coupling (see Fig. 116). With the ring and claw fastened in this way, they will never fall out of the coupling.

Attach a ring to one sleeve and a foot to the other. Place the test tube in the paw in a vertical position, with the hole facing up. The test tube is properly secured if it can be turned in the claw without much effort. A test tube that is clamped too tightly may burst, especially when heated. The test tube is usually clamped near the hole. Turn the same test tube into a horizontal position so that the foot screw is on top.

Place a net on one ring of the tripod and place a glass on it. Place a porcelain cup without a mesh on the second ring.

3. Techniques for working with an alcohol lamp (gas burner). An alcohol lamp (Fig. 117) consists of a vessel (reservoir) (1) into which alcohol is poured, a wick (2) mounted in a metal tube with a disk (3), and a cap (7). Remove the cap from the spirit lamp and place it on the table. Check whether the disk fits tightly to the opening of the vessel; it must be completely closed, otherwise the alcohol in the vessel may ignite.

Rice. 117. Alcohol lamp

Light the alcohol lamp with a burning match. You cannot light it from another burning alcohol lamp! This may cause a fire. Extinguish the alcohol lamp by covering the flame with the cap.

4. Flame structure. Light the alcohol lamp again and look at the structure of the flame. The flame (see Fig. 117) has three zones. The dark zone (4) is at the bottom of the flame and is the coldest. Behind it is the brightest part of the flame (5). The temperature here is higher than in the dark zone, but the most heat- in zone 6. This zone is in the upper third of the alcohol lamp flame.

To make sure that different zones of the flame have different temperatures, you can perform the following experiment. Let's place a splinter (match) in the flame of a spirit lamp so that it passes through zone 4. After a while we will see that where the splinter crossed zones 5 and 6, it becomes more charred. Therefore, the flame in these zones is hotter.

Observation shows that for the fastest heating, you need to use the hottest part of the flame (c). A heated object is placed in it.

5. Dishes. Most experiments are carried out in glassware: test tubes, beakers, flasks (Fig. 118). During the experiment, they have to mix the contents. As a rule, small quantities of substances (no more than 2 ml) are mixed in a test tube. The height of the liquid column when mixing solutions in a test tube should not exceed 2 cm.

Rice. 118. Samples of chemical glassware: a - test tube; b - beaker; c - flask

Do not shake the test tube while covering the hole with your finger. Firstly, getting any quantities chemical reagents dangerous on skin; secondly, in this case, contaminants may get into the test tube, and the experiment will not work.

Mixing solutions in a test tube is done with quick, energetic movements (tapping), as shown in Figure 119. In a flask, the contents are mixed in a circular motion, and in a glass, with a glass rod, putting a piece of rubber tube on its end so as not to damage the wall of the glass.

Rice. 119.
Mixing solutions in a test tube

Funnels are used to pour liquids from wide-necked dishes into a vessel with a narrow neck (Fig. 120). They are also used for filtering. In this case, a paper filter (a circle of filter paper) is placed in the funnel, which is cut to the size of the funnel.

Rice. 120.
Chemical funnel

First, the filter paper must be folded and cut, as shown in Figure 121, and then placed in a funnel and moistened with water so that it fits more tightly to the walls of the funnel and so that the dry filter does not absorb the filtered liquid (if there is little of it, then you may not get a filtrate at all) .

Rice. 121.
Sequence of making a paper filter

When filtering, the liquid is poured onto the filter over a stick in a thin stream, directing it towards the wall of the funnel, and not at the fragile center of the filter, so as not to tear it. A clear filtrate passes through the filter, and sediment is retained on the filter. For subsequent work, you may need both.

Porcelain cups are used for evaporation (Fig. 122).

Rice. 122.
Porcelain evaporation cup

Evaporation is used when it is necessary to separate a solute from a solution. The solution is poured into a porcelain cup so that it occupies no more than 1/3 of the volume of the cup. Place the cup on the tripod ring and heat over an open flame with constant stirring so that evaporation occurs evenly.

Rice. 123.
Device for obtaining gases

To obtain gases, a simple device is used, which consists of a flask or test tube and tightly fitting plugs with gas outlet tubes (Fig. 123), or a Kiryushkin apparatus (Fig. 124).

Rice. 124.
Kiryushkin apparatus

A device assembled to produce gases is always first checked for leaks (Fig. 125). To do this, the tip of the gas outlet tube is lowered into a glass of water, and the flask or test tube is tightly clasped with the palm of your hand.

Rice. 125.
Checking the gas tightness of the device

From a warm palm, the air in the vessel for producing gas expands, and if the device is assembled hermetically, air bubbles come out of the gas outlet tube.

Application

Laboratory alcohol lamp

Used in tourism for cooking; in chemical and school laboratories for heating and melting materials, for heating small laboratory vessels (test tubes, flasks for chemical work, etc.) and other similar thermal processes; in medical institutions for sterilization of medical instruments in an open flame; and also wherever the use of an open flame of low thermal power is required.

Design

Trangia travel set, including dishes and alcohol lamp on the left.

The alcohol container is the main supporting part of a laboratory alcohol lamp, and its most important and main part is the wick, which transfers liquid fuel (alcohol) from the container to the end of the wick, where this fuel burns and is used for heating. The alcohol container is made in the form of a reservoir into which the lower end of the wick is lowered. The reservoir has a neck, which is equipped with a lid. The lid is necessary to separate the alcohol combustion zone from the internal volume of the tank where the liquid fuel is located. The reservoir cover can be placed both inside the neck and outside it, covering the latter from the outside. A guide tube is usually installed in the hole in the lid through which the wick passes. The wick must be placed in the tube in such a way that, on the one hand, it can move smoothly and easily in the tube, and on the other hand, the contact of the tube with the wick must be tight enough so that the wick does not fall out of the tube. The lid of the spirit lamp may have a device for adjusting the protruding length of the wick, the recommended value of which is no more than 15 mm.

Typically, fuel for a spirit lamp is poured through the top hole of the tank after removing the lid. However, there are alcohol lamps whose tank has a side filler neck with a ground-in cap. The amount of fuel poured is determined by the internal volume of the tank. The alcohol from the reservoir rises up the wick due to capillary pressure and evaporates when it reaches the upper end of the protruding part of the wick. The alcohol vapor is ignited and the alcohol lamp burns with a flame temperature of no higher than 900° Celsius. Most alcohol lamps have a metal or glass cap, which is used both to extinguish the flame of the alcohol lamp and to prevent evaporation of the fuel.

In terms of structural elements, laboratory alcohol lamps differ from each other in the following parameters:

• tank material (metal or glass);
• tank shape (round or faceted);
• internal volume of the tank;
• wick material and thickness;
• the presence or absence of a device for regulating the protruding part of the wick;

The tank material should be selected based on the operating conditions of the alcohol lamp. If the alcohol lamp is used in conditions where it is possible that the alcohol lamp may accidentally fall onto a stone or metal floor, then from a safety point of view it is preferable to use a spirit lamp with a metal reservoir. Alcohol lamps with a glass body are much cheaper than metal ones. In addition, when operating a spirit lamp, you can always monitor the level of alcohol in the tank. However, glass is a fragile material that has little resistance to impact, and therefore there is always the possibility of destruction of the spirit lamp tank if it falls on a hard floor, which can cause a spill of burning alcohol. Therefore, in rooms with increased fire safety requirements, the use of glass spirit lamps, especially those made of thin laboratory glass, is not recommended.

The round shape of the tank is most widely used. Faceted spirit lamps are more expensive than round ones and should be used only when performing a number of specific jobs, for example, those associated with heating low-melting materials such as waxes, in order to prevent drops of heated material from getting onto the wick of the spirit lamp.

The internal volume of the alcohol lamp tank must be chosen such that during its operation, at a minimum, there would be no need to refill the alcohol lamp during one hour of its continuous operation.

The material and thickness of the wick are important elements for the operation of a spirit lamp. Wicks made of cotton fabric and asbestos cord are used. The most widespread are wicks made of cotton fabric, as they give a more stable and even flame compared to asbestos wicks. As for the thickness of the wicks, we must proceed from the fact that the thicker the wick, the more fuel it supplies to the combustion zone. Thicker wicks also produce a larger flame with a higher flame height. As a result, the thermal power of alcohol lamps with a thicker wick is slightly higher, but the alcohol consumption is also higher. For most laboratory work performed using alcohol lamps, a wick thickness of at least 4.8 mm and no more than 6.4 mm is sufficient. Thicker wicks are necessary for some professional jobs that require a high, voluminous flame. It is advisable to have alcohol lamps with different wick thicknesses in the set and use them depending on the technological requirements for the work being performed.

A device for adjusting the size of the protruding part of the wick provides great convenience when working with alcohol lamps, since it is not necessary to extinguish the flame of the alcohol lamp each time in order to adjust the flame parameters (height and volume) by changing the size of the protruding part of the wick. Alcohol lamps with devices for adjusting the protruding part of the wick are more expensive than alcohol lamps without these devices. However, the slightly higher price is more than offset by the professional work amenities this device provides.

Fuel

All alcohol lamps primarily use ethyl alcohol as fuel. There are three types of ethyl alcohol on sale: rectified ethyl alcohol from food raw materials, hydrolytic technical alcohol from wood raw materials and synthetic alcohol obtained by chemical means. Industrial alcohol and synthetic alcohol are sometimes colored blue-violet with the addition of certain substances with a pungent odor. This alcohol is called denatured alcohol. All these types of alcohols can be used as liquid fuel for alcohol lamps.

Other types of fuel, such as isopropyl or methyl alcohol, are not recommended for use in laboratory alcohol lamps, since these alcohols have a maximum permissible concentration in the air that is two or more orders of magnitude lower than that of ethyl alcohol and is therefore hazardous to health.

Safety precautions

When working with laboratory alcohol lamps, safety rules are as follows. It is necessary to use the alcohol lamp only for the intended purpose specified in its technical data sheet. Do not refuel the alcohol lamp near open flame devices. Do not fill the alcohol lamp with fuel more than half the capacity of the tank. Do not move or carry a spirit lamp with a burning wick. It is strictly forbidden to light the wick of a spirit lamp using another spirit lamp. Fill the alcohol lamp only with ethyl alcohol. Extinguish the flame of the alcohol lamp only with the cap. Do not keep flammable substances and materials that can ignite from short-term exposure to an ignition source with low thermal energy (match flame, alcohol lamp) on the workbench where an alcohol lamp is used. The room in which work with alcohol lamp(s) is carried out must be equipped with primary fire extinguishing means, for example, a powder fire extinguisher.

Advantages

• Light weight - no more than 220 g.
• Ease of use - you only need to add fuel, which is independently supplied to the combustion area.
• Reliability - all design elements are practically trouble-free in operation.
• Quiet operation.
• No pungent odors - the smell of liquid fuel before it is ignited is negligible compared to the smell of gaseous fuel in similar cases.
• No maintenance required - there is no need to carry out routine or repair work to adjust and clean structural elements.
• Safety at work - the fuel used in small quantities is not explosive, spilled burning alcohol can be easily extinguished using standard fire extinguishing agents (powder fire extinguishers).
• Easy to store fuel - fuel can be stored in a regular plastic bottle or plastic canister.
• Low price - the cost of alcohol lamps is significantly lower than laboratory gas burners or other types of burners that use liquid fuel (kerosene, gasoline).
• Environmentally friendly fuel - does not pollute the environment (it is safe when released into water and soil and does not form toxic substances during combustion).

Flaws

• Low thermal power - the calorific value of ethyl alcohol is lower than that of other types of liquid fuel (kerosene, gasoline) and gaseous fuel (methane, propane).
• Unreliable operation at low temperatures - poor evaporation of fuel from the protruding upper part of the wick at sub-zero temperatures.
• Low mechanical strength - parts of alcohol lamps have low strength and can be deformed or destroyed even under slight mechanical stress.

see also

Links

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