Types of thermometers and their application. What is the best temperature thermometer? History of the thermometer

A thermometer (or more correctly called a thermometer) is a device that can be found in any apartment. With it, you can measure the temperature of the body, soil, water or air. It is used in various areas of life: medicine, cooking, agriculture, in various industries, with scientific purposes and others. Measurement of air temperature at home and on the street allows people to navigate in weather conditions, and fever associated with an increase in body temperature is a symptom of a large number of diseases (for example, infectious). The thermometer is indispensable assistant in different situations, and submit modern life without it it is simply impossible.

There are several types of thermometers:

Liquid (alcohol thermometer, mercury thermometer),
mechanical thermometer,
optical thermometer,
Gas thermometer.

The history of the modern thermometer goes back to the Middle Ages. The inventor of thermometers is considered to be Galileo, whose students described that in 1597 he invented a device that records changes in water temperature. It was a tube filled with liquid and a ball that floated on its surface. When the water was heated, its level rose and the ball with it, when cooled, everything happened in the reverse order. However, this device could not be called a true thermometer, because with it it was impossible to determine how many degrees in the room or how much hot water, that is, he did not have any scales and graduations. And, nevertheless, this primitive device became the prototype of a real thermometer.

FROM mid-seventeenth century began the history of the first liquid thermometers. However, the first tests were not crowned with success - when the temperature dropped below zero degrees, they burst. The reason was that the tube was filled with water. The situation changed radically when ethyl alcohol was used as a liquid, which freezes at a much lower temperature.

The modern form of the thermometer acquired as a result long work scientist Fahrenheit (1723). At the beginning of his activity, he used alcohol as a liquid, and only after many years - mercury. He identified the main control points: melting ice, boiling water and body temperature. healthy person. His work was continued by another scientist - Celsius (1742). He took for 0 - the level of ice melting, and for 100 - the boiling of water and calibrated the thermometer. He also found out that these parameters depend on the level at which the device is relative to the sea.

Types of thermometers

There are several types of thermometers, each of them works according to its own special principle. Each has advantages and disadvantages, and, accordingly, the area where they best help to carry out thermometry.

A liquid thermometer is a special device for measuring temperature, the basic principle of which is based on the expansion of a certain liquid. It is widely used in various fields of science, technology and medicine. It is a capillary that contains liquid. Depending on the increase in its temperature, it increases in volume and its level rises. A special division is applied to the capillary, taking into account the fact that one degree corresponds to a certain level of rise in the column of this liquid. Various types of liquid thermometers allow you to measure temperatures from -200°C to +750°C. The most commonly used alcohol thermometer and mercury thermometer, much less often other varieties (kerosene, pentane, etc.).

mercury thermometer

A mercury thermometer is a device that not everyone has, although a few decades ago it was mandatory in any home first aid kit. It was replaced by the modern electronic thermometer and became more popular than its predecessor for safety reasons. However, a number of experts still prefer the mercury medical thermometer, since, in their opinion, its readings are more accurate.

A mercury thermometer is a device whose main element is a thin tube from which air is pumped out. At the end of it is a special reservoir with mercury (brilliant gray color). Along the tube there is a special bar on which a scale is applied. Each division of this scale indicates a certain temperature interval (1 or 0.1 ° C).

The mechanism of action of a mercury thermometer for the body is as follows: room temperature all mercury is in the tank, but when it enters a higher temperature environment, it expands and the column rises. As a result, the level stops at a level corresponding to the actual temperature, if we talk about human use, it helps to detect the presence of fever or normothermia. If the thermometer is intended to determine weather conditions or how hot it is in the apartment, then it is attached to the appropriate surface (wall, window frame, platband, etc.). As a result, a home thermometer will help determine whether it is time to ventilate the room and how to dress outside.

A medical mercury thermometer differs from the one that is designed to determine the temperature on the street or in the apartment in that after removing it from the area of the human body, the column does not fall down on its own. This is due to the special structure of the entrance to the mercury tank (it is slightly narrowed). Therefore, many people know that in order to delete the previous readings on such a thermometer, it is necessary to shake it several times.

A mercury thermometer for the body has its advantages:

Measurement accuracy (the most reliable after a gas thermometer),
Low cost(20-30 rubles),
Availability in all pharmacies of our country,
The possibility of treatment with disinfectants (therefore, a mercury thermometer for the body is used in all hospitals),
Long service life - no batteries required.

The mercury thermometer has its disadvantages:

Measurement duration (5-10 minutes),
The presence of mercury in the composition of the hazardous substance,
When falling, it breaks
Cannot be used for oral temperature measurement in children.

An alcohol thermometer is also widely used by people, like a mercury one. It has a similar principle of operation as the last one. Only unlike him, the tube contains not mercury, but alcohol. It is very easy to distinguish between these two types of thermometer: by the color of the liquid in the tank. In a mercury thermometer it is brilliant gray, and in an alcohol thermometer it is red, because it is this shade that special dyes give this solution. The red bar is clearly visible from a distance. However, the alcohol thermometer has not found its application for measuring body temperature, its niche is to determine the number of degrees in the room and on the street, temperature various liquids(in laboratories, in production, in cooking). It has a gradation from -40°С to +50°С.

Other types of liquid thermometers

In addition to the mercury and alcohol thermometers, kerosene and pentane are also classified as liquid. The first allows you to determine the temperature level in the range from -20°C to +300°C, the second - from -200°C to +20°C. Kerosene thermometers are used to obtain information about the course of technological processes, pentane thermometers are used in the manufacture of various alloys from several metals.

Mechanical thermometer

A mechanical thermometer has the same principle of operation as a liquid one. That is, the ability to expand is taken as the basis various materials under the influence of elevated temperature. A distinctive feature of a mechanical thermometer is the presence of two tapes with different physical properties. When the temperature rises, they begin to move relative to each other, which is reflected on the dial.

Mechanical thermometers have not found their application in medicine. Their niche is the determination of temperature in various electrical appliances or mechanical devices (for example, in a toaster), they also produce mechanical thermometers to determine the temperature in a room.

The electronic thermometer went on sale several decades ago, but its popularity is growing every day. Many families, especially those with babies, prefer this particular temperature device and believe that this is the best thermometer for children.

The principle of operation of an electronic thermometer is based on determining the temperature level by a special sensor built into its housing. The measurement result is displayed on the display, the measurement accuracy is 0.1°C. It has found its use exclusively in medicine, as it quickly determines body temperature anywhere (in the mouth, armpit, vagina or rectum).

An electronic thermometer for the body has its advantages:

Durable: won't break when dropped.
It does not contain a hazardous substance - mercury.
Thanks to the presence of a case, this is the best thermometer for trips and travel.
Fast results (less than 1 minute).
The ideal thermometer for children - allows you to determine the temperature even in the mouth without fear that the baby will bite off the tip or accidentally drop it on the floor.
Modern.

The production of mercury thermometers is decreasing every year. This means that the electronic medical thermometer will gradually completely replace it from household use. After all, it is much more convenient, safer, faster to use. However, it also has certain disadvantages:

The cost ranges from 200-1000 rubles, which is not affordable for every family.
Available for sale mainly in cities, rural and rural pharmacies are not always able to provide customers with an electronic thermometer.
Inaccurate readings. When changing the temperature level in the same person in the same place several times in a row, it can give results that differ by a few tenths of a degree.
It can break down (like any electronic device), require repair or even replacement.
The battery needs to be changed regularly.
After a beep has sounded indicating that the temperature has been measured, the level may rise further if the measurement is continued. This should be taken into account.
It is not treated with disinfectants and sterilized, that is, it is not suitable for use in a large number of people (clinic or hospital). Therefore, it is a home thermometer that is suitable for use by members of the same family.
Runs on small batteries that can be taken out and swallowed by very smart kids. Therefore, the question of whether a thermometer is dangerous can be answered in the affirmative.

Optical thermometer

An optical thermometer is a rather complicated device in which the temperature is measured using various photocells and photomultipliers. They evaluate the brightness of the incident light, which bodies with different temperatures give off with different intensity. For comparison, heat is taken from a light bulb heated to 600-800 ° C. Naturally, such a device is not suitable for household use or for measuring body temperature. Its role is the use in production, in laboratories, etc.

gas thermometer

The gas thermometer is based on the Charles principle. It lies in the fact that while maintaining the same volume, the same increase in body temperature leads to the same increase in pressure. A change in temperature leads to a fluctuation in pressure. A vessel with gas is connected to a pressure gauge (a device for measuring the pressure level), respectively, the temperature can be determined from this indicator using a special calibration.

Hydrogen or helium is used as the gas, although it has been proven that the specific type does not affect the final result. A gas thermometer is the most accurate of all existing ones, but it cannot be definitely called a home thermometer: it is used in experiments, experiments, and in production.

An infrared thermometer is a novelty in the world of thermometers, which is gaining popularity among buyers. The principle of operation of this device is associated with the registration of infrared radiation emanating from a certain surface, the level of which directly depends on temperature. A sensitive sensor captures this radiation and transforms this indicator into a temperature level, the result can be seen on the display.

The infrared thermometer has found wide application in pediatrics. It allows you to quickly and accurately measure the temperature of a sleeping child without having to wake him up. There is a forehead and ear version of this thermometer, for thermometry it is necessary to attach it to the corresponding area for a few seconds.

The infrared medical thermometer has several advantages:

Security. A child cannot break it, injure a hand on glass, or inhale mercury vapor.
The best thermometer for travel or trips.
Quick measurement result within seconds.
An infrared thermometer for children is an excellent choice, it allows you to take thermometry from a sleeping baby.
In addition to body thermometry, it allows you to measure the temperature of any liquids or solids, for this you need to configure a specific mode.

However, in addition to the advantages of an infrared thermometer, it also has certain disadvantages:

High cost (2000-3000 rubles).
Runs on batteries so keep a spare.
Ear and forehead thermometers only measure temperature in these areas.
In order for the thermometer to show the correct result, a person must sit still for several seconds. With kids, this is very difficult to achieve.
Not entirely reliable result (the error is 0.5-1.0 ° C).
In order to re-measure, you must wait a few seconds.
Ear thermometer does not show correct result at , the tip does not fit into the ear canal of the smallest patients. With active movements of newborns, it can injure the ear, so such a thermometer can be dangerous for them. Also, you need to buy special nozzles for it.

A non-contact thermometer is one of the varieties of infrared, distinctive feature which no need to touch the device to the skin. This is the most ideal thermometer for children, because it can take thermometry without disturbing the child (who can sleep, play or eat mother's milk).

A non-contact thermometer is more properly called a pyrometer. The principle of its operation is to measure the power of thermal radiation from an object (which can be a person, a liquid or a solid object). However, the device takes into account only infrared radiation and transforms the result into a certain temperature indicator.

The advantages of a non-contact thermometer are similar to those already described for all infrared thermometers. However, a feature of this particular type is that it allows you to measure the temperature on any part of the body without touching it. This is especially true for babies who cannot take thermometry with a mercury or electronic thermometer.

The disadvantages of a non-contact thermometer are also similar to all infrared ones. However, its cost is even higher than ear or frontal ones (3-4 thousand rubles), but given that this is a one-time purchase, this amount can be allocated from family budget almost every family. In addition, the readings of a non-contact thermometer are somewhat dependent on environment so the temperature in the room should not be too low or too high.

Dummy thermometer

The pacifier thermometer is another trendy invention for pediatric thermometry. He is the best thermometer for children younger age who have not yet weaned from the pacifier. This device has a special sensor built into the body, which determines the temperature in the same way as an electronic thermometer. The result becomes visible on the display 60 seconds after the start of the measurement.

The dummy thermometer is a truly unique invention. It cannot be broken, which can happen with a mercury thermometer. The process of thermometry does not cause discomfort to the baby. However, it also has disadvantages:

Batteries need to be changed.
The cost is about 400 rubles.
Like any device, it can break.
Unlike a regular pacifier, it cannot be fully sterilized or boiled.
Not suitable for children who do not like to suck on a pacifier (and there are many).

Thus, we see that a home thermometer can be selected according to needs. Each of them has its own advantages, disadvantages and scope.

A thermometer is a multifunctional device that a person uses in various areas of life. Its main role in medicine is the determination of body temperature, because it the most important parameter state of the body. The normal indicator fluctuates in the range of 36.6-37.1 ° C (in the armpit). In the mouth and rectum, it may differ slightly, depending on various parameters (hot food intake, phase menstrual cycle etc.). Temperature in the range of 37.1-37.9°C is subfebrile, 38.0-38.9°C is febrile, 39.0-41.0°C is pyretic and above 41.0°C is hyperpyretic and potentially dangerous for life.

The task of a medical thermometer is to determine body temperature as quickly and accurately as possible. This indicator affects correct setting diagnosis and timely treatment. An elevated temperature without a thermometer can also be detected quite simply, but sometimes minutes count and it is simply pointless to neglect such an elementary device (especially for young children).

In medicine, the following types of thermometers are used:

mercury,
electronic,
infrared, including non-contact.

In hospitals and clinics, preference is still given to mercury thermometers due to the fact that the durable glass case is easily disinfected in various antiseptic solutions. After all, quite often a lot of people will use it during the day, so the issue of cleanliness in this aspect is very important.

For home use electronic or infrared thermometers are more suitable, since in the vast majority of cases they are used by members of the same family and special treatment with disinfectants is not required. However, they sometimes give errors, therefore, in order to determine whether the thermometer is correct or not, its readings should be checked periodically with a standard mercury thermometer, whose operation is not affected by anything.

Measuring body temperature with a thermometer

Measuring body temperature or thermometry is an important procedure that allows you to detect the presence of fever, as a symptom of a large number of serious illnesses. The most important rules, which determine in which place it is better to take a measurement and how long to hold the thermometer, help to do this as efficiently as possible. Therefore, each person should know how to carry out thermometry in order to recognize a fever in time and seek help from a doctor.

Measuring body temperature is a procedure that directly depends on what type of thermometer is used for this.

Rules for thermometry with a mercury thermometer

When measuring temperature with a mercury thermometer, the first thing to find out is what are the readings from the previous thermometry on the device (after all, as mentioned above, the level of the mercury column does not return to the minimum mark on its own). If the indicator is above 35 ° C, then the thermometer should be gently shaken several times. Then re-evaluate the level. Next, the device must be placed in the armpit. The question of how long to keep the thermometer is very important, because if you remove it ahead of time, you can get an underestimated unreliable result. The duration of the mercury thermometer in the armpit should be at least 5-6 minutes, ideally - 10. After that, it should be removed and the readings evaluated.

Rules for thermometry with an electronic thermometer

The rules for using an electronic thermometer are described in the instructions for this device. Before using it for the first time, as well as any other, you should read it carefully. Each electronic thermometer has its own characteristics that relate to thermometry technology. Before starting the procedure, you need to look at the display and reset the previous readings (although for some devices this happens automatically). Then place it in the armpit, mouth or rectum. The waiting period for the result is determined by the appearance of a special sound signal. However, for greater accuracy, you should continue measuring the temperature for another 1-2 minutes, sometimes these results differ.

Rules for thermometry with an infrared thermometer

An infrared thermometer is a device that also requires reading the instructions. Each manufacturer makes its own nuances in the process of thermometry, so this should always be remembered. The question of how long to keep such a thermometer should also be clarified in the text of the instructions, but usually the result is displayed on the display for 1 minute.

It must be remembered that periodically any thermometer needs to be processed. A mercury thermometer can be rinsed with an antiseptic solution (you can use a weak alcohol one), but electronic and infrared thermometers can fail after such a procedure. They should simply be wiped with a clean, damp cloth after each use.

The question of how long to keep the thermometer is very important. After all, its premature extraction leads to an underestimated result. The result is an underestimation of the severity of your condition. Therefore, for different types of thermometers, this parameter is individual:

Mercury thermometer.

Preferably 5-6 minutes, ideally 10 minutes.

Preferably - before the sound signal (1-2 minutes), ideally - 1-2 minutes after the sound signal.

Preferably - before the sound signal (60 seconds). After that, further measurement is meaningless. A non-contact thermometer shows the result on the display after 30 seconds.

How to determine elevated temperature without a thermometer

Fever is a symptom that, as a rule, has a very specific effect on the patient's well-being. Therefore, elevated temperature without a thermometer can also be diagnosed quickly enough. Here are a few signs to suspect a fever:

Feeling, trembling (during the process of raising the temperature), or heat - when it has already risen to high numbers.
Redness of the skin of the face, chest.
Headache, dizziness, weakness, drowsiness.
Pain in muscles, joints, bones, a feeling of aching in the body.
Thirst, dry mouth, loss of appetite.

Children behave in a very specific way when they have a fever. They become lethargic, whiny, refuse to eat and play, ask to be held by their parents. It is possible to determine the presence of a high temperature without a thermometer, however, only the device can determine its specific level, so do not neglect it.

Young children often get sick, and colds occur in them much more often than in adults due to immaturity. immune system. Fever in a child often develops, and it can quickly reach pyretic numbers. Babies in the first 2 years of life are very vulnerable to high fever, because one of its potential complications is febrile convulsions. They occur against the background of an increase in body temperature to a level of 39 ° C and above and are the result of underdevelopment nervous system. To prevent their occurrence, it is necessary to determine the presence of a fever in the baby as soon as possible and urgently take measures to reduce body temperature. Therefore, the presence of a thermometer in a house where there are children is mandatory, and its absence is a negligent crime of parents.

best thermometer for baby

An increase in body temperature in infants up to a year is extremely serious and dangerous symptom. Any mother should be able to measure this indicator, despite the fact that the child himself may not be enthusiastic about this procedure. Fortunately, today there are different kinds thermometers that help to carry out thermometry in the smallest patients. These include thermometers - pacifiers, electronic and infrared thermometers. Most best option: non-contact thermometer, it helps to measure the sleeping baby.

A mercury thermometer is the most extreme option, because a baby can react specifically to a cold glass device - by hitting a handle or a leg, break the thermometer.

The right thermometer for preschool children

Children between the ages of 1 and 6 years differ greatly in terms of development. Six-year-old children are conscious people who can sit quite calmly for several minutes while measuring temperature with any kind of thermometer, which cannot be said about two-year-olds: this procedure can cause a storm of negative emotions in them. Therefore, when choosing the type of thermometer, you must first take into account the temperament of the baby. A dummy is an option that will only suit one year old baby, therefore, after 2 years, infrared, non-contact or electronic thermometers should be preferred.

Cases when preschool children accidentally broke a thermometer are not uncommon. That's why this option should be left first of all in order to find out whether the correct thermometer is infrared or electronic, or whether the batteries or the device itself should be replaced.

The question of whether a thermometer containing mercury is dangerous and whether mercury poisoning from a thermometer is possible worries all owners of this device. Around him there have always been many myths and legends that are not entirely true. Therefore, this issue, as well as what to do if the thermometer is broken and how the thermometers are disposed of, should be given special attention.

Is mercury poisoning possible from a thermometer?

Is mercury poisoning possible from a thermometer? Here main question, which is spinning in the head of a person who sees small shiny balls of this liquid metal on the floor, which got there as a result of careless handling of the thermometer. However, experts say that the dose of this substance in one device is so small that real mercury poisoning from a thermometer is very unlikely. However, the chances increase if the balls hit a hot stove, frying pan, then the metal evaporates and this increases the likelihood of them getting into the respiratory tract.

Also, the likelihood of getting chronic mercury poisoning from a thermometer increases if the balls rolled somewhere in a secluded place and stayed there for long time. To prevent this from happening, it is necessary, after breaking the thermometer, to carry out all necessary measures prevention of this serious condition.

What to do if the thermometer is broken

If such a situation has occurred in the house, the first thing to do is to isolate all animals and children in a separate room. After that, you need to tightly close the doors, open the window wide open and start collecting mercury balls. This must be done in rubber gloves, by gluing them on adhesive tape or paper in a large glass jar. After a thorough inspection of the scene of the incident, it is necessary to close the jar tightly and call the rescue service so that they conduct a control measurement of the residual level of mercury and dispose of the thermometer.

How is the disposal of mercury thermometers

An old or broken mercury thermometer is a potential environmental hazard. Therefore, the disposal of thermometers based on mercury is the task of specialists. Ideally, they must be handed over in a tightly closed bag or bank to the employees of the city rescue service. Do not throw them in the trash or take them to the landfill yourself.

Disposal of mercury thermometers is a serious job that must be carried out by specially trained professionals.

The article describes the various types of thermometers used to determine the temperature, focuses on the principle of operation and features.

It also tells about the types of medical devices according to the method of their use, there are characteristics of rectal, ear, head-on devices.

Popular manufacturers and the approximate cost of devices are also indicated.

Thermometers for determining body temperature - what are they

For diagnosis various diseases do not do without thermometers.

There are various types of thermometers. Let's list them:

mercury;
electronic;
rectal;
ear;
on the forehead;
infrared.

These types of medical thermometers are used to detect deviations in the temperature of the human body.

High rates may be evidence of various pathologies - this may relate to inflammatory diseases, brain diseases, oncological diseases, etc.

About the principles of operation of various types of thermometers

An electronic thermometer consists of a thermistor, which is the main component of this device.

When the reading fluctuates, it changes the resistance level. To protect the electronic thermometer from damage, its body is made of materials that do not allow moisture to pass through.

After the measurement, a beep can be heard. You can find out the result by looking at the display of the medical device.

Electronic medical thermometer: body temperature is shown on the display. For convenient storage transparent case included

A feature of this model is the presence of interchangeable caps, they are needed for hygienic purposes, they are included.

In order to use the electronic thermometer, you need to press only one button. The result can be seen on the LCD display.

For an accurate result, it is best to use it in the rectum or mouth.

Advantages of electronic thermometers:

affordable price;
in a maximum of 3 minutes you can find out the result;
they are safe in operation - even if the device breaks down, it will not bring harm to human health;
universality;
there will be no problems if the device falls into water or on the floor;
Availability additional features in some devices - they can measure the temperature in the room, remind you of the need for what should be measured again;
you can find completely waterproof models.

Electronic thermometer

There are also disadvantages of such devices. Let's list them:

if you try to measure with a device under your arm, then most likely it will give inaccurate readings;
it takes 5 to 10 minutes to measure under the arm, and this is despite the fact that the end of the process signal will sound earlier.

Different types of thermometers allow you to choose any you like, but the most common is mercury.

mercury thermometer

Its peculiarity is that it can remember the last reading. Now this product is the leader in sales.

However, mercury is the sending substance. Fragility - main disadvantage device. then the mercury will come out.

To minimize damage, mercury variants are sold in capsule shells. Even if the thermometer breaks, the mercury will remain inside the capsule.

We list the advantages of mercury thermometers:

easy to use;
affordable;
measure the temperature in different parts of the body.

This type of thermometer has its drawbacks:

fragile glass;
mercury is dangerous for human well-being;
the device may fall and break;
if it breaks, you can get hurt by the glass.

The principle of operation of a glass thermometer is based on the fact that mercury expands at elevated body temperature: the metal begins to rise along the glass tank.

It is believed that a mercury thermometer is able to give the most reliable readings.

The case is used to store the mercury device. The device should be stored dry, upside down.

The above classification of thermometers includes infrared thermometers. They are also used to determine the temperature of the human body.

Infrared models are most often ear thermometers: you need to insert the sensor into the ear, the results will be displayed on the screen. The end of the procedure will be signaled by a signal, just like in electronic models.

A feature of such thermometers is the presence of a backlight.

Infrared thermometer

The infrared thermometer has its advantages:

suitable for taking the temperature of a patient who is unconscious or sleeping;
you can measure the temperature in newborns;
it is not necessary to apply the device to the body;
backlit options available;
for measurement it is necessary to wait only 2 s;
very convenient to use;
the device is also suitable for measuring ambient temperature, water;
additional features include the presence of removable sterile tips and a shockproof housing.

This type of thermometer also has disadvantages:

high price;
not suitable for measuring basal temperature.

The operation of such devices is based on the presence of an ultra-sensitive component that reacts to infrared rays emanating from the human body.

All information is displayed on a liquid crystal display. The fact that the device has completed its work can be recognized by the sound signal.

If the device is backlit, then you can see the readings even at night.

Let's talk about. Please read the instructions before using them.

Rectal thermometer

With the help of such devices, you can monitor the state of human health. This device is able to show the temperature measured in the anus.

They are usually used by women. With the help of such thermometers, you can monitor the state of the reproductive function, which will help you find out hormonal background on different days.

Also used to measure body temperature in children - this should be done only when the child is calm.

The thermometer must be inserted into the anus by a maximum of 5 centimeters. It is recommended to use lubricant during the procedure. For this, a baby cream or lubricant is suitable.

They wait a few minutes, then they take out the thermometer and look at the indicators. After use, the tip of the device is treated with an antibacterial wipe.

Using a rectal thermometer

Such thermometers can also be called digital.

Rectal thermometer

We list the advantages of such thermometers:

after the end of the measurement, a sound signal is heard;
well suited for children under the age of 3 years;
the convenience of use;
since the sensor is located on the tip, it does not need to be inserted too deeply for measurement.

Rectal thermometer

Also, such thermometers have their drawbacks:

fragility;
high price.

forehead thermometer

To quickly take the temperature, use thermometers on the forehead. They can be both electronic and in the form of stickers.

Sticker thermometer

For measurement, the forehead must be clean and dry. The thermometer is applied to the middle of the forehead, while the device should be held on both sides. Don't touch the numbers with your fingers.

If you use a sticker, then 20 seconds is enough to find out the temperature. Do not use the sticker thermometer under bright lamps or direct sunlight.

The advantages of such thermometer stickers:

they can be used many times;
they measure the temperature as quickly as possible;
small size;
no batteries needed for operation;
the composition does not contain mercury and components harmful to humans;
especially convenient to use when traveling;
can be used to measure the temperature of sleeping children;
with their help, you can monitor whether the temperature drops.

Of the minuses, the following can be noted:

the sticky layer loses its properties over time, so you have to press the sticker thermometer with your hands to your forehead.

Also can be used. They are also called technical.

liquid thermometer

It consists of a scale, a capillary tube, a liquid, a bypass chamber, a thermometer ball.

The principle of its operation is in the properties of liquids to expand and contract.

When the liquid is heated, it expands, the liquid begins to rise up the capillary tube, which indicates an increase in temperature.

Advantages of liquid thermometers:

wide application;
high measurement accuracy;
ease of use.

They also have their downsides:

it is impossible to automatically record readings;
poor visibility of the scale.

A manometric device is used to measure the temperature of gaseous and liquid neutral media.

The principle of the device is based on measuring the pressure of a substance enclosed in a limited space. The readings are affected by the temperature of the sensing element.

Translated from Greek means "to measure heat". The history of the invention of the thermometer dates back to 1597, when Galileo created a thermoscope - a ball with a soldered tube - to determine the degree of heating of water. This device did not have a scale, and its readings depended on atmospheric pressure. With the development of science, the thermometer has changed. The liquid thermometer was first mentioned in 1667, and in 1742 the Swedish physicist Celsius created a thermometer with a scale where 0 was the freezing point of water and 100 was the boiling point.

We often use a thermometer to determine the temperature of the air outside or body temperature, but the use of a thermometer is by no means limited to this. Today, there are many ways to measure the temperature substances, and modern thermometers are still being improved. Let us describe the most common types of temperature meters.

The principle of operation of this type of thermometer is based on the effect of liquid expansion when heated. Thermometers that use mercury as a liquid are often used in medicine to measure body temperature. Despite the toxicity of mercury, its use allows you to determine the temperature with greater accuracy compared to other liquids, since the expansion of mercury occurs according to a linear law. In meteorology, alcohol thermometers are used. This is primarily due to the fact that mercury thickens at a value of 38 ° C and is not suitable for measuring more than low temperatures. The range of liquid thermometers is on average from 30 ° C to +600 ° C, and the accuracy does not exceed one tenth of a degree.

gas thermometer

Gas thermometers work on the same principle as liquid thermometers, only they use an inert gas as a working medium. This type of thermometer is analogous to a manometer (a device for measuring pressure), the scale of which is graduated in units of temperature. The main advantage of a gas thermometer is the ability to measure temperatures near absolute zero (its range is from 271 °C to +1000 °C). The maximum achievable measurement accuracy is 2*10 -3 °С. Obtaining a high accuracy gas thermometer is challenging task, so these thermometers are not used in laboratory measurements, but are used for the primary determination of the temperature of a substance.

This type of thermometer works by analogy with gas and liquid. The temperature of the substance is determined depending on the expansion of the metal spiral or bimetal strip. The mechanical thermometer is highly reliable and easy to use. As independent devices, such thermometers have not received wide distribution and are currently used mainly as devices for signaling and controlling temperature in automation systems.

Electric thermometer (resistance thermometer)

The operation of an electric thermometer is based on the dependence of the conductor resistance on temperature. The resistance of metals increases linearly with increasing temperature, which is why metals are used to create this type of thermometer. Semiconductors, compared with metals, provide greater measurement accuracy, however, thermometers based on them are practically not produced due to the difficulties associated with grading the scale. The range of resistance thermometers directly depends on the working metal: for example, for copper it ranges from -50 °C to +180 °C, and for platinum - from -200 °C to +750 °C. Electric thermometers are installed as temperature sensors in production, in laboratories, on experimental stands. They are often bundled with other measuring devices.

Also called thermocouple. A thermocouple is a contact between two different conductors that measure temperature based on the Seebeck effect, discovered in 1822. This effect consists in the appearance of a potential difference at the contact between two conductors in the presence of a temperature gradient between them. Thus, through the contact with a change in temperature, begins to pass electricity. The advantage of thermocouple thermometers is the ease of execution, a wide range of measurements, the possibility of grounding the junction. However, there are disadvantages: the thermocouple is subject to corrosion and other chemical processes with time. Thermocouples with electrodes made of noble metals and their alloys - platinum, platinum-rhodium, palladium, gold - have maximum accuracy. The upper limit of temperature measurement using a thermocouple is 2500 °C, the lower limit is about -100 °C. The measurement accuracy of the thermocouple sensor can reach 0.01 °C. A thermocouple-based thermometer is indispensable in industrial control and monitoring systems, as well as in measuring the temperature of liquid, solid, granular and porous substances.

Fiber Optic Thermometer

With the development of optical fiber manufacturing technologies, new opportunities for its use have arisen. Fiber-optic sensors are highly sensitive to various changes in external environment. The slightest fluctuation in temperature, pressure or tension of the fiber leads to changes in the propagation of light in it. Fiber optic temperature sensors are often used to ensure industrial safety, for fire alarms, monitoring the tightness of containers with flammable and toxic substances, leak detection, etc. The range of such sensors does not exceed +400 °C, and the maximum accuracy is 0.1 °C .

Infrared thermometer (pyrometer)

Unlike all previous types of thermometers, it is a non-contact device. You can read more about pyrometers and their characteristics in a separate one on our website. A technical pyrometer is capable of measuring temperature in the range from 100 °C to 3000 °C, with an accuracy of several degrees. Infrared thermometers are convenient not only in production conditions. Increasingly, they are used to measure body temperature. This is due to many advantages of pyrometers compared to mercury analogues: safety of use, high accuracy, minimum time for temperature measurement.

In conclusion, we note that now it is difficult to imagine life without this universal and irreplaceable device. Simple thermometers can be found in everyday life: they are used to maintain the temperature in the iron, washing machine, refrigerator, ambient temperature measurement. More complex sensors are installed in incubators, greenhouses, drying chambers, and in production.

The choice of a thermometer or temperature sensor depends on the scope of its use, the measurement range, the accuracy of the readings, and the overall dimensions. And the rest - it all depends on your imagination.

- an important indicator of the state of the body.

Body temperature is measured for:

diagnosing fever, monitoring the patient's condition, response to treatment;
diagnosis of low temperature (hypothermia) in people with prolonged exposure to conditions with low air temperature;
diagnosing elevated temperature (hyperthermia) and heat stroke in people with prolonged exposure to conditions with elevated air temperature;
testing the effectiveness of antipyretics;
determining the period of ovulation when planning pregnancy.

Preparatory measures

Like pressure indicators, each person has his own normal temperature. To determine your indicator of normal body temperature, you should measure it several times with good health in the morning and evening hours, since the readings can vary during the day by 0.6°C.

Temperature should be measured no earlier than 20-30 minutes after smoking, eating and drinking hot or cold drinks and no earlier than one hour after intensive physical activity or taking a hot bath.

Types of thermometers

Electronic thermometers- plastic devices shaped like a pencil, with a temperature probe at one end and a display at the other. They measure the speed of current flow through a built-in diode. Electronic thermometers measure the temperature in the mouth, rectum and under the arm. They are the easiest to use and give the fastest results.

Ear thermometers are also made of plastic and have different shape. Their action is based on measuring the energy of infrared radiation. The cone-shaped end of the thermometer is placed in the ear, after which the body temperature is displayed on the display. Results appear within seconds. Some models also indicate the expected temperature in the mouth and rectum.

Disposable thermometers

Disposable - thin plates with colored dot markings and temperature values \u200b\u200bat the end. The temperature is determined by the color of the dots. These thermometers can be used to measure temperature in the mouth or rectum. They can be used to measure the surface temperature of the skin in infants. Disposable thermometers are safe but not as accurate as electronic or ear thermometers. They do not contain glass, latex and mercury. You can reuse a disposable thermometer when you are sick, but then discard it.

Head thermometers

Head thermometers measure body temperature based on the temperature of the forehead skin. Some of them have a soft nozzle, when applied to the forehead, the result is displayed on the display. Others are in the form of plastic strips with temperature readings that change color or glow when applied to the forehead. These instruments are not as accurate as electronic or ear thermometers.

Thermometer teats

Pacifiers-thermometers are made in the form of pacifiers for children, on the outside they have a display to display the temperature. To measure, you just need to place the thermometer in the baby's mouth like a normal pacifier. However, when using them, the results take longer and are not as accurate as with other types of thermometers.

Mercury thermometers

Their action is based on the ability of mercury to expand with a change in temperature. They allow you to determine the temperature in the mouth, in the rectum and under the arm, but the result is shown after 5-10 minutes, which is not very convenient for children. The use of glass thermometers containing mercury is not recommended. If you have such a thermometer at home, it is advisable to take it to a medical facility.

To date, thermometers are absolutely in every home. And in Lately the installation of room devices that measure temperature has become increasingly popular. In addition, do not forget about the mercury types of thermometers, the human body. In general, the range of application of these devices is very large. According to the place of installation, window, facade, water, room and even bath thermometers are distinguished. Types of devices in composition and design are less extensive. In addition to the classic mercury, there are infrared and electronic.

Outdoor mercury types of thermometers

Photo number 1 shows us a standard window thermometer, which is probably in every apartment. Its main advantage is high measurement accuracy and low price. However, due to the use of such a dangerous metal as mercury, it is very dangerous to use it at home. And in order not to provoke depressurization of the device, it is necessary to protect it from various mechanical damages. However, for outdoor thermometers this is not as important as, for example, for household ones that measure the temperature of the human body. As for the scale, window thermometers can show temperatures from -50 to +50. They are usually installed on or on glass. But it's not all devices.

Electronic thermometers

Types of outdoor (window) devices are not limited mercury thermometers. For example, an electronic device is very interesting (indicated in the second photo). It has a small sensor, a wire and a liquid crystal display.

This design allows you to control the outside temperature without leaving the sofa. How does it work? Sensors are brought out into the street that measure the temperature and transmit a signal via wires to the display. Thus, you can mount an electronic thermometer in almost any room in order to monitor its readings from there.

Water thermometers

Types of such devices are most often intended for bathing young children. Parents use them to control the temperature of the water while bathing, which is especially important for newborns. The scale of such devices is designed for readings from +10 to +50 degrees Celsius. At the same time, some water thermometers are supplied with a red mark on a scale of 37 degrees Celsius. This indicator is just the most optimal for bathing children.

Also, some thermometers (types and varieties of mercury) can be in the form of animals and cartoon characters, which attracts the attention of a baby who is learning about the world around him. However, remember that such a thermometer can be damaged in the hands of a child. And this means that mercury can simply depressurize, which is very dangerous for human health. Therefore, in this case, select devices that are maximally protected from mechanical damage or electronic. But the latter are much more expensive than mercury thermometers. Thermometers, human bodies, can be mercury, electronic and infrared. The third option is the safest and most accurate of its kind, so keep it in your first aid kit.