Mercury thermometer diagram. Mercury thermometer

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In our time, when digital and electronic technologies are actively developing and are entering all spheres of human activity, playing an increasingly important role and becoming more and more indispensable for each of us, there are ordinary objects and things from our everyday use that will serve us for a long time and be useful.

Such items include the well-known “ thermometer", or as it is more correct to call it - mercury medical thermometer.

Even after the appearance of a large number of models of electronic thermometers, the mercury thermometer has not lost its popularity and is the most common device for measuring the temperature of the human body.

The main element of a mercury thermometer is a capillary tube. The tube is sealed on both sides and the air is pumped out of the inside of it. At one end of the tube there is a reservoir of mercury. There is a special scale for measuring temperature. The scale is marked on a bar attached to the tube. The measurement range of the scale is from 34 to 42 degrees Celsius. To accurately measure body temperature, each degree on the scale consists of 10 divisions equal to 0.1 degrees Celsius.

The fundamental difference between a medical thermometer and conventional mercury thermometers for measuring ambient temperature is that the junction of the reservoir with mercury and the capillary tube is specially curved and slightly narrowed, which in turn makes it difficult for the mercury to move in the opposite direction.

Thanks to this design of the “thermometer”, when measuring the temperature of a person’s body, mercury heats up, expands and slowly reaches its maximum level, showing the correct temperature.

But at the same time, after stopping the temperature measurement and influencing the thermometer, the mercury does not change its position and the reading on the scale is fixed at the maximum value that was achieved during the measurement. That is why the medical thermometer is called maximum.

To return the thermometer to its initial position in order to further application and measuring temperature, you need to shake the “thermometer”, thereby returning the mercury back to the reservoir.

Advantages of a mercury thermometer:

A mercury medical thermometer, due to its characteristics, is the most accurate in its performance and is close in readings to a gas thermometer, which is considered a reference thermometer. Therefore, a mercury thermometer measures the temperature of the human body more accurately than other thermometers.
At the same time, a mercury thermometer is less susceptible than others to the influence of extraneous factors and temperature measurement conditions.
The design of the mercury “thermometer” allows its disinfection with complete immersion in a disinfectant solution, therefore it is suitable for healthcare and medical institutions.
Compared to electronic thermometers, a regular “thermometer” is very attractive for its price to any buyer (the cost of a medical mercury thermometer is 25-50 rubles). But here the following feature should be taken into account. A mercury thermometer is quite difficult to produce. Requires mercury High Quality and special cleaning. Required special equipment for environmentally friendly production. Therefore, mercury thermometers are being produced less and less, and electronic thermometers are being produced more and more. And with the subsequent development of technology, electronic thermometers will become significantly cheaper over time.
The most primitive design of the thermometer ensures simplicity and accessibility of use.

Disadvantages of a mercury thermometer:

It takes a long time to measure body temperature. On average, temperature measurement should last at least 5-6 minutes, and the most accurate measurement requires 10 minutes.
But the main disadvantage of a mercury thermometer is the mercury itself. It is the presence of mercury (about 2 grams) that is a dangerous substance for human health, and the glass design of the “thermometer,” which easily breaks, negates all the advantages of a mercury thermometer compared to all others.

Mercury is a liquid with a silver-metallic sheen that begins to evaporate at temperatures of +18°C and above.

Mercury is a silvery-white metal. But the metal is unusual, in our traditional understanding. The melting point of mercury is very low for metals and is equal to -38.9 degrees Celsius.

Due to this specific property, normal conditions, for example, at room temperature, mercury is a readily mobile liquid, which, when struck lightly, separates into small balls, and when combined, easily reunites into a single ball.

Another property of mercury is that it begins to evaporate already at a temperature of +18°C and above.

If it crashes in a room or apartment mercury thermometer, then the mercury after impact breaks into many small drops and spreads throughout the room. At the same time, mercury can easily penetrate into the pile of carpets, into cracks in floors, and into the cracks between the baseboard and the floor. Then mercury, actively evaporating, pollutes and poisons all available air in the room.

If a person breathes this air constantly, over time, mercury begins to accumulate in the body, which in turn leads to chronic mercury intoxication, which can manifest itself as a metallic taste in the mouth, headaches, diarrhea, kidney damage, stomatitis, salivation, anemia, dermatitis, tremors limbs.

How to use a mercury thermometer correctly?

Before each measurement of body temperature, it is necessary to check the thermometer by carefully inspecting it. If the mercury reading exceeds 35 C, you must shake off the thermometer.

Shaking the thermometer is done as follows:

Take top part thermometer into your fist so that the head of the thermometer rests securely in your palm, the reservoir of mercury points down, and the middle of the thermometer is between your thumb and forefinger
Several times, with a jerky movement at the elbow joint, forcefully lower your hand down, while making a sharp stop of the hand, so that the “thermometer” actually shakes.
After measuring the temperature, the mercury thermometer must be disinfected, but in no case should you wash the mercury thermometer with hot water. If exposed to hot water, it may lose its accuracy or even deteriorate or even crack.

Before eliminating the consequences of a broken mercury thermometer, you need to prepare:

A glass jar with a tight-fitting lid for preserving collected mercury.
Medical cotton wool, pieces of plaster, a sheet of thick paper, and rags.
Large plastic bags for disposal of items that may be contaminated with mercury.
A knitting needle or a thick needle, a medical syringe.
A flashlight or table lamp with an extension cord for lighting.
Latex gloves.
Chemicals that have oxidizing (bleaching or disinfecting) properties and containing chlorine compounds (bleach, chlorinol, etc.). A solution of potassium permanganate from the first aid kit may be useful.

The first stage of mercury removal is demercurization.

Demercurization is the collection of droplets of mercury. This is the most important and time-consuming stage.

Never use a vacuum cleaner to remove dust. There are two main reasons for this.

Firstly, the vacuum cleaner itself will become contaminated with mercury particles, and it will be impossible and dangerous to use it in the future.

Secondly, the filters of the vacuum cleaner will not retain all the mercury, and most of it, already in sprayed form, will again end up in the room and settle on all possible surfaces (from which it will be difficult to collect it), and in large quantities will get into your lungs.

Remove all people not involved in cleaning from the room. Be sure to remove children and pets from the apartment. Keeping children and animals in a contaminated room is dangerous to their health, and they can spread mercury throughout the room or even ingest it.
First of all, conduct a thorough inspection of all objects, surfaces and objects that may have received droplets of mercury. It is worth considering that elastic mercury balls roll very well on any surface, and can be very small in size.
It is better to use a flashlight prepared in advance to illuminate all corners, crevices, cracks in the floor, recesses and irregularities. Due to its metallic luster, mercury is easier to see in bright light.
All items susceptible to mercury contamination must be collected and placed in plastic bags and taken out into fresh air from the contaminated room.
When inspecting horizontal surfaces and floors, especially parquet or laminate flooring, it is necessary to mark in advance with chalk or pencil the places where mercury particles were found. Avoid stepping on these contaminated areas to avoid getting mercury on your shoes.
The collection of mercury must begin with the largest drops so that they do not break into smaller droplets. To make it easier to clean up mercury, it is best to use a thick sheet of paper, folded in half, or in the shape of a scoop. To roll drops of mercury onto a sheet of paper, use a thick needle or knitting needle.
By carefully bringing the drops closer to each other, you can combine several small drops into one large one. Carefully place large drops into the prepared glass jar.
To collect very small drops of mercury, use a small piece of plaster or adhesive tape. Small drops of mercury should be retained by the sticky side of the patch. Place the patch with drops of mercury stuck to it in a glass jar.
Drops of mercury can be removed from cracks in the floor, parquet or other objects using a needle with a cotton swab wrapped around it. To be effective, the tampon should be soaked in a solution of potassium permanganate. Place the tampon with drops of mercury stuck to it in a glass jar.
Drops of mercury can also be removed from the cracks using a medical syringe with a thick needle.
If you suspect that mercury particles have gotten behind the baseboard, under the laminate or under the parquet floorboard, they should be removed and carefully inspected.
Collecting mercury particles from a broken thermometer may take you several hours. For the safety of your health and to avoid mercury vapor poisoning, every 10-15 minutes you should take a break and go out into the fresh air.

Once you have collected all the mercury, it should be handled very carefully and with care. Close the jar of mercury with a tight lid to prevent mercury vapor from escaping. Under no circumstances should you throw mercury into the trash, garbage chute, or toilet. This will only lead to new, very difficult to remove pollution. A jar of collected mercury can be temporarily placed on a balcony or in a garage, providing all means for its integrity, and then handed over to representatives of the rescue service.

The second stage of mercury removal is chemical demercurization.

It is necessary to proceed to the stage of chemical demercurization only if all visible droplets of mercury have been removed and all objects and things susceptible to contamination have been collected and removed from the room.

To do this, you will need chemicals available at home. Most accessible remedy, which can be found in any first aid kit, is potassium permanganate. Depending on the area of the surface to be treated, we prepare a solution of potassium permanganate. To be on the safe side, it is better to prepare one liter at once.

To prepare the solution, pour water into a jar and add a few crystals of potassium permanganate to obtain an almost opaque dark brown solution. Based on the proportion per liter of water, add and dissolve a tablespoon of table salt, as well as a tablespoon of vinegar essence or a pinch citric acid. Mix the resulting solution carefully and thoroughly so that no particles remain.
We put on rubber gloves and begin to treat the contaminated surface with the resulting solution. When treating surfaces, special attention should be paid to cracks, crevices and corners where mercury particles could remain. You can even pour a little solution into such places for more reliable treatment.
After applying the solution to the surface, leave it for 7-8 hours. As the solution dries, it is necessary to periodically moisten the treated surface with clean water.
After time has passed, the treated surface is thoroughly washed using detergents and cleaning agents. chemicals. After which you need to do a high-quality wet cleaning throughout the entire apartment.
To prevent the consequences of a broken thermometer, daily wet cleaning of the apartment and frequent long-term ventilation are carried out.
Usually, after a week of high-quality cleaning and ventilation, it is possible to completely get rid of mercury particles in the apartment.

What to do after eliminating the consequences:

After collecting mercury, you must contact the Ministry of Emergency Situations for help by calling 101 to transfer them a jar of mercury.
Drink as much liquid as possible (water, tea, coffee, juices), since mercury formations are eliminated from the human body through the kidneys.
If you suspect that mercury is still present in your apartment, call specialists with a mercury gas analyzer. For measurements, please contact the regional centers of hygiene and epidemiology.

What not to do:

Do not throw a broken thermometer or mercury particles into the trash or into the garbage chute. Two grams of mercury contained in a thermometer is enough to pollute six thousand cubic meters of ambient air.
Do not flush mercury down the drain. It tends to settle in sewer pipes, and it is almost impossible to extract mercury from the sewer.
Do not collect mercury using a vacuum cleaner. A vacuum cleaner, blowing air with mercury, will evaporate the liquid metal, thereby polluting the surrounding air in the room. In this case, you will have to throw away the vacuum cleaner, as it will be dangerous to use.
Do not sweep up mercury particles with a broom. The hard rods of the broom will only crush the poisonous balls of mercury into fine mercury dust, which will immediately enter your lungs.
You cannot wash things, clothes and shoes that have come into contact with mercury, either with your hands or with the help of washing machine. It's better to throw these things away altogether.

Maybe it's time to get rid of the mercury in the house?

The fact that mercury thermometers are dangerous has been recognized in the EU and in a number of other countries. That is why the use of mercury thermometers is prohibited in medical and healthcare institutions. Sales are prohibited measuring instruments containing mercury, including thermometers and thermometers. This measure can significantly reduce the amount of toxic mercury entering the environment with household waste.

Electronic thermometers are the best alternative to mercury thermometers. Since there is no mercury or glass in their body, they are absolutely safe to use for humans, including when measuring in the mouth. And the speed of measurement and the presence of memory distinguishes them favorably from the old mercury thermometer./p>

What to do if a mercury thermometer breaks? This is the most important question that those who prefer to use this device have to face at least once in their lives. Mercury vapor is very harmful to the body and can cause serious illness.

To understand this issue, you must first become familiar with the operating principle of this device and how to use it correctly.

The thermometer consists of a capillary tube in which there is no air. It is hermetically sealed on both sides. At one end of the tube there is a container with mercury.

A capillary tube with mercury is attached to a bar with a printed scale. The scale values range from 32 to 42 ºС. Each degree is divided in turn into another 10 divisions for more accurate measurements. One mark is equal to 0.1 ºС.

A medical thermometer differs from a conventional thermometer, which measures the ambient temperature, in that the movement of mercury in the opposite direction is difficult. This occurs due to a narrowed channel that connects the capillary tube to the mercury reservoir.

First, the patient’s temperature is measured with a thermometer: the mercury heats up, expands and rises through the tube, showing the maximum value. After stopping the measurement procedure, the mercury in the thermometer remains below its maximum value for a long time. This property of the thermometer is very convenient for monitoring the patient’s condition until the doctor arrives.

To “return the mercury” to its original position, just shake the thermometer vigorously several times. But this must be done carefully so as not to drop the fragile instrument..

Advantages of a mercury thermometer:

It is more accurate, unlike its modern counterparts.
Practically does not respond to changes in environmental conditions. That is, under any conditions, a mercury instrument will show the most objective indicator of the temperature of the human body.
It can be easily disinfected by dipping it in a special solution that is used by medical institutions.
The reasonable price makes it accessible to a wide range of consumers.

Disadvantages of a medical thermometer:

Measures temperature long time: about 7-10 minutes.
Mercury poisoning from breaking a thermometer. The thermometer has a very thin glass shell, which easily loses its integrity when it hits the floor.

Before using the thermometer, shake it well so that the mercury liquid returns to its original position.
Keep the thermometer on your body for at least 10 minutes.
After each use, the device should be disinfected, but not with hot water. To do this, you can wipe it with a cotton swab soaked in hydrogen peroxide.
Do not leave a fragile item without its case.
Don't fall asleep with him.
Do not give to children.

Advice: If he lives at home Small child, which through carelessness can break a fragile device, it is better to purchase an electronic instrument for measuring temperature.

A mercury thermometer has broken - what to do?

So the biggest disadvantage of this home appliance is the loss of its integral structure. If a thermometer is broken, what should you do? Droplets of mercury should be collected as quickly as possible and the room should be disinfected. But this must also be done correctly, since mercury has its own specific properties.

Why is mercury and its vapor dangerous?

Mercury is a silvery liquid with a metallic tint. It begins to evaporate already at a temperature of +18 ºС. Mercury is a metal that begins to melt at a temperature of -38.9 ºС. It is traditionally believed that metals are solids with a very high melting point.

If a thermometer breaks in an apartment, the silvery liquid that was inside it disintegrates on the surface in the form of small balls. At the same time, these microparticles can get into the carpet pile, sofa upholstery, under the bed, on children's toys, in the crevices of baseboards and furniture.

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Then these droplets will begin to evaporate at room temperature and enter the air that households breathe. Excess mercury in the body can lead to the following diseases:

headache;
gastrointestinal disorder;
disorder in the functioning of the kidneys;
stomatitis;
anemia;
dermatitis;
increased heart rate;
blurred vision;
neuroses;
convulsions.

So, to the question: “the thermometer broke, is it dangerous?”, you can answer this way:

Mercury is hazardous to health in large quantities. Even if a person does not immediately feel a deterioration in his condition, then later the evaporating mercury will make itself felt.
It is especially dangerous for pregnant women and children to breathe mercury vapor.

Thus, it is necessary to eliminate the broken thermometer as quickly as possible and collect droplets of silvery liquid.

What to do with a broken thermometer

First steps if the thermometer breaks:

All household members, including animals, must leave the premises. At the time of cleaning the apartment, no one should be at home.
Close tightly the room where the device fell and open all windows. But drafts in in this case unacceptable.
To eliminate traces of a broken thermometer, you need special equipment: rubber gloves and a cotton-gauze bandage. The mask should be moistened in a solution of water and soda. If you have a respirator, you can use it.
It is necessary to prepare a flashlight or lamp to provide good illumination of the scene of the incident.
Put shoe covers or plastic bags on your feet so they can be thrown away later.
First, remove the fragments of the thermometer, and then proceed to the mercury.

How to collect mercury from a thermometer:

rubber syringe;
copper plate;
syringe or knitting needle;
wet cotton wool;
brush;
wet newspaper.

You can’t just throw silver balls into a bucket, so you need to prepare a glass jar with water. Water will prevent the mercury from evaporating and spreading through the air.

All tools that were involved in cleaning up the toxic liquid are wrapped tightly in a plastic bag and then taken out of the apartment to the trash. The jar of water in which the mercury was collected is also tightly closed and handed over to the Ministry of Emergency Situations employees.

Stages of cleaning a broken thermometer

As soon as all the tools for cleaning the thermometer have been prepared and the first steps have been taken, you can begin cleaning the room. This process is divided into the following stages:

demercurization – removal of mercury globules;
chemical demercurization - disinfection of the premises;
calling the Ministry of Emergency Situations.

Stage No. 1: remove metal balls from all objects in the apartment

First of all, it is necessary to conduct a thorough inspection of all surfaces and objects in the apartment. It should be noted that mercury material is very fine and can roll into the most inaccessible places: under the bed, between cabinets, into the carpet. Therefore, for inspection you need to use a bright flashlight.

If affected items can be thrown away, it is better to get rid of them. This applies to clothes and toys. If items contaminated with mercury cannot be thrown away, then they should be taken outside or onto the balcony so that they are cleared of toxic fumes.

When inspecting the floor, the affected areas should be marked (circled with a pencil) so as not to accidentally step on mercury. After all, the metal balls will remain unnoticeably on the shoes and begin to evaporate.

Large drops are collected first so that they are not separated into small fractions. To do this, take a thick sheet of paper and bend it in half in the form of a scoop. Next, take a copper plate (knitting needle, needle, syringe) and collect balls with this object onto a sheet of paper.
The drops are moved into one pile so that they are reunited into one whole piece.
Small balls can be collected onto a patch.
To get mercury liquid out of the cracks of furniture, take a cotton swab and dip it in a solution of potassium permanganate. This stick is used to get mercury in hard-to-reach places.
If the cracks are very tight, then in this case you can use a syringe with a thick needle.
You can collect drops from the carpet with a syringe. Drops of it are sucked out of the thick pile, and the syringe itself is wrapped in a plastic bag and thrown away. The carpet itself should be taken out into the fresh air so that all traces of harmful metal evaporate from it.
The collected particles are placed in a glass jar. Band-aids and cotton swabs are also placed there. The jar is tightly closed and then handed over to the Ministry of Emergency Situations employees.

Demercurization may take several hours. In order not to be poisoned by harmful fumes, you need to go out into the fresh air every 15 minutes, and carry out work in a cotton-gauze bandage or a respirator.

What not to do if the thermometer breaks:

Touch the mercury balls with your bare hands.
Collect crushed metal with a magnet. Mercury is diamagnetic, meaning it has a very weak magnetic field. It will not be attracted to the magnet, but rather, on the contrary, repelled from it.
Remove metal balls using a magnet and a vacuum cleaner. When a vacuum cleaner blows air, it can release mercury back into the air. In addition, mercury heated by a vacuum cleaner will begin to evaporate intensively into the air. It will no longer be possible to remove mercury from a vacuum cleaner; the household appliance will only have to be thrown away.
You should also not use a broom to remove toxic particles. Hard rods will crush the mercury balls even more, which will evaporate faster and settle on the lungs.
Throw away the remaining mercury thermometer down the drain and into the trash. Silver liquid in a volume of 2 grams can pollute 6000 cubic meters of air.
Items that were involved in eliminating traces of the accident cannot be washed. It's better to throw them away.

Stage No. 2: carry out chemical disinfection

This requires chemicals that have disinfectant properties and contain chlorine molecules. The simplest substance in this case may be ordinary potassium permanganate, which is found in the first aid kit of every apartment.

To prepare the solution, you need to add several crystals of calcium permanganate into a jar of water until the liquid turns dark brown. Next, add 1 tablespoon of table salt to 1 liter of water, and the same amount of vinegar, as well as a pinch of citric acid. Everything should be mixed thoroughly.

Wearing rubber gloves, disinfect the room:

Using a soft cloth soaked in the prepared solution, wipe all places where mercury could get in: the floor, furniture. Particular attention should be paid to cracks and corners.
The applied solution is left on the surface for 8 hours. After this, wipe the floor and all surfaces with plain clean water.
Next, do wet cleaning using conventional cleaning products.
The apartment is cleaned daily during the week. This is the only way to finally get rid of traces of the incident.

Instead of potassium permanganate, you can use ferric chloride. Make a 20% solution and wipe all objects with it.

A good alternative to disinfection is regular bleach.. For 5 liters of water take 1 liter of bleach. This liquid is used to wash the floor, baseboards and walls. After 20 minutes, the chlorine solution is washed off plain water and provide ventilation without drafts. There is no need to overcool the room, as this will make the mercury evaporate worse.

However, you cannot wipe laminate and wallpaper with bleach - this can ruin the material. Bleach is used mainly in medical and government institutions: hospitals, kindergartens, schools.

Stage No. 3: what to do after eliminating a broken thermometer

When the apartment is cleaned and ventilated, the last steps should be taken:

Contact the Ministry of Emergency Situations by calling 101 and give their employees a jar containing the collected poison.
If there are still suspicions that mercury balls remain somewhere in the apartment, then you need to call the employees of the sanitary and epidemiological station who have special devices, determining the level of harmful vapors. There are special centers that deal with the disposal of mercury and the remains of a broken thermometer.
After the incident, mercury in small doses, one way or another, enters our body. Therefore, you need to drink more liquid: juices, water, compote, tea, in order to remove harmful substances from the body.

It should be noted that there are cases when a small child swallows mercury from a broken thermometer. This comes as a shock to many mothers. But it's in vain!

Mercury drops that enter the body are not absorbed by the intestines, but are excreted along with feces. Much more dangerous than mercury vapor, which affects the lungs. But in this case, you must definitely apply for medical care see a specialist.

How long does it take for mercury to disappear if a thermometer breaks in an apartment? The remaining mercury evaporates within a few hours. However, the room where the thermometer crashed must be ventilated for at least a day, without people or animals being there.

If the thermometer breaks at home, it’s not a problem. Required knowledge and proper cleaning will rid the room of harmful fumes and eliminate all signs of danger.

Today it is almost impossible to imagine life without a thermometer. Of course, you can find out about the temperature outside from the weather report. But how can you determine the heat level in the room, oven, drying chamber or a greenhouse? There is no way to do this without a thermometer.

There are several types:

liquid;
mechanical;
gas;
electrical;
optical.

Liquid

The operating principle of such a device is based on the effect of expansion or compression of a liquid that fills a flask and changes its volume as its own temperature fluctuates. Usually, mercury or alcohol is poured into it, which subtly react to minimal changes in heat in the environment.

In medicine, mercury thermometers are usually used, but in meteorology they are filled with alcohol, since the mercury column can freeze at -38 degrees.

Mechanical

The operating principle of this type of device is also based on expansion. But with its help, the temperature is determined depending on the expansion of the bimetallic strip or metal spiral.

These are characterized by high accuracy, they are reliable and easy to use.

However, they are not used as a separate, independent model; they are usually used in automated systems.

Gas

Gas type temperature meter works on the same principle as liquid device. It uses some inert gas as a working substance.

The advantage of this device is that it can measure temperatures approaching absolute zero, and its measurement range ranges from -271 to +1000 degrees. This is a rather complex device that is rarely used in laboratory measurements.

Electrical

The operation of such a measuring device is related to the dependence of the resistance of the conductor used on temperature. It is known that the resistance of any metals linearly depends on the level of their heat. More accurate measurements can be obtained by replacing metal conductors with semiconductors. However, semiconductors are practically not used in such devices, since the relationship between the characteristics of the semiconductor and the heat level cannot be expressed linearly and it is almost impossible to calibrate the instrument scale.

Copper usually acts as a conductor, showing temperature changes from -50 to +180 degrees. If we take another working metal, for example, platinum, then temperature Range it will expand significantly and range from -200 to +750 degrees. Such electrical thermal sensors are used in laboratories, at experimental stands or in production.

Optical

Optical instruments or pyrometers allow you to find out the temperature by the level of luminosity of a body, analysis of its spectrum and some other parameters. This is a non-contact device capable of measuring, with an accuracy of several degrees, the level of heat in a wide range - from 100 to 3000 degrees. Most often in practice we come across infrared household thermometers. Such thermometers are very convenient because they allow you to safely, quickly and accurately determine a person’s body temperature.

There are other, more complex temperature meters, such as fiber optic or thermoelectric. These are very sensitive instruments that give the most accurate measurement results with virtually no error.

Useful tips

A thermometer is a device designed to measure the temperature of a liquid, gaseous or solid medium. The inventor of the first device for measuring temperature is Galileo Galilei. The name of the device is translated from Greek as “to measure heat.” Galileo's first prototype was significantly different from modern ones. The device appeared in a more familiar form more than 200 years later, when the Swedish physicist Celsius began studying this issue. He developed a system for measuring temperature by dividing the thermometer into a scale from 0 to 100. In honor of the physicist, temperature levels are measured in degrees Celsius.

Varieties based on operating principle

Although more than 400 years have passed since the invention of the first thermometers, these devices are still being improved. In this regard, new devices are appearing based on previously unused operating principles.

Nowadays there are 7 types of thermometers:

Liquid.
Gas.
Mechanical.
Electrical.
Thermoelectric.
Fiber optic.
Infrared.

Liquid

Thermometers are among the very first instruments. They work on the principle that liquids expand when temperature changes. When a liquid heats up, it expands, and when it cools, it contracts. The device itself consists of a very thin glass flask filled with a liquid substance. The flask is applied to a vertical scale made in the form of a ruler. The temperature of the medium being measured is equal to the division on the scale indicated by the liquid level in the flask. These devices are very accurate. Their error is rarely more than 0.1 degrees. IN various designs liquid instruments capable of measuring temperatures up to +600 degrees. Their disadvantage is that if dropped, the flask may break.

Gas

They work exactly the same as liquid ones, only their flasks are filled with inert gas. Due to the fact that gas is used as a filler, the measuring range increases. Such a thermometer can show maximum temperatures ranging from +271 to +1000 degrees. These instruments are usually used to take temperature readings of various hot substances.

Mechanical

The thermometer works on the principle of deformation of a metal spiral. Such devices are equipped with an arrow. They look a little like a clock. Similar devices are used on car dashboards and various special equipment. The main advantage of mechanical thermometers is their durability. They are not afraid of shaking or shocks, like glass models.

Electrical

The devices operate on the physical principle of changing the resistance level of a conductor at different temperatures. The hotter the metal, the more resistant it is to transmission. electric current higher. The sensitivity range of electric thermometers depends on the metal used as a conductor. For copper it ranges from -50 to +180 degrees. More expensive platinum models can indicate temperatures from -200 to +750 degrees. Such devices are used as temperature sensors in production and laboratories.

Thermoelectric

The thermometer has 2 conductors in its design that measure temperature according to the physical principle, the so-called Seebeck effect. Such devices have a wide measurement range from -100 to +2500 degrees. The accuracy of thermoelectric devices is about 0.01 degrees. They can be found in industrial production when measurement is required high temperatures over 1000 degrees.

Fiber Optic

Made from fiber optics. This is very sensitive sensors, which can measure temperatures up to +400 degrees. Moreover, their error does not exceed 0.1 degrees. This thermometer is based on a stretched optical fiber, which stretches or contracts when the temperature changes. A ray of light passing through it is refracted, which captures optical sensor, which compares refraction with ambient temperature.

Infrared

The thermometer, or pyrometer, is one of the most recent inventions. They have an upper measurement range from +100 to +3000 degrees. Unlike previous types of thermometers, they take readings without direct contact with the substance being measured. The device sends infrared ray onto the surface being measured, and displays its temperature on a small screen. However, the accuracy may differ by several degrees. Similar devices are used to measure the heating level of metal workpieces that are located in the furnace, engine housing, etc. Infrared thermometers can show temperatures open flame. Similar devices are used in dozens of different areas.

Varieties by purpose

Thermometers can be classified into several groups:

Medical.
Household for air.
Kitchen.
Industrial.

Medical thermometer

Medical thermometers are usually called thermometers. They have a low measuring range. This is due to the fact that the body temperature of a living person cannot be below +29.5 and above +42 degrees.

Depending on the design, medical thermometers are:

Glass.
Digital.
Pacifier.
Button.
Infrared ear.
Infrared frontal.

Glass thermometers were the first to be used for medical purposes. These devices are universal. Usually their flasks are filled with alcohol. Previously, mercury was used for such purposes. Such devices have one big drawback, namely the need for a long wait to display real body temperature. For axillary execution, the waiting time is at least 5 minutes.

Digital thermometers have a small screen on which body temperature is displayed. They are able to show accurate data 30-60 seconds after the start of measurement. When the thermometer reaches its final temperature, it creates sound signal, after which it can be removed. These devices may operate with errors if they do not fit very tightly to the body. There are cheap models of electronic thermometers that take readings no less long than glass thermometers. However, they do not create a sound signal about the end of the measurement.

Thermometers nipples made especially for small children. The device is a pacifier that is inserted into the baby's mouth. Typically, such models emit a musical signal after completing the measurement. The accuracy of the devices is 0.1 degrees. If the baby begins to breathe through his mouth or cry, the deviation from the actual temperature can be significant. The measurement duration is 3-5 minutes.

Thermometers buttons They are also used for children under three years of age. The shape of such devices resembles a pushpin, which is placed rectally. These devices take readings quickly, but have low accuracy.

Infrared ear The thermometer reads the temperature from the eardrum. Such a device is capable of taking measurements in just 2-4 seconds. It also comes with a digital display and runs on . This device is illuminated to facilitate insertion into the ear canal. The devices are suitable for measuring temperature in children over 3 years of age and adults, since infants have too thin ear canals into which the tip of the thermometer does not fit.

Infrared frontal thermometers are simply applied to the forehead. They work on the same principle as ear ones. One of the advantages of such devices is that they can operate without contact at a distance of 2.5 cm from the skin. Thus, with their help you can measure the child’s body temperature without waking him up. The speed of operation of forehead thermometers is several seconds.

Household for air

Household thermometers are used to measure air temperature outdoors or indoors. They are usually made in glass and filled with alcohol or mercury. Typically, their measurement range in outdoor settings is from -50 to +50 degrees, and in indoor settings from 0 to +50 degrees. Such devices can often be found in the form of interior decorations or refrigerator magnets.

Kitchen

Kitchen thermometers are designed to measure the temperature of various dishes and ingredients. They can be mechanical, electrical or fluid. They are used in cases where it is necessary to strictly control the temperature of the recipe, for example, when preparing caramel. Typically, such devices come complete with a sealed tube for storage.

Industrial

Industrial thermometers are designed to measure temperature in various systems. They are usually mechanical type instruments with a pointer. They can be seen in water and gas supply lines. Industrial models are electrical, infrared, mechanical, etc. They have the widest variety of shapes, sizes and measurement ranges.

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