A device for determining indoor air humidity. Instruments for measuring relative air humidity. Hair room hygrometer

What you breathe directly affects your health, reflects your standard of living, and builds your immune system. Therefore, the issue of air humidification is important, namely how and with what to measure the air humidity in the apartment in order to remain in good health, feel a surge of vigor, and be in unity with harmony and energy.

What indicator is used to determine the optimal level of humidity in a room?

In order for the entire body to feel comfortable, the air must be humid, but this figure must be within 45%. This is an average value, but for rooms with different functional purposes the humidity level is different:

for an office and library it is 40-45%;
for the dining room, bathroom, kitchen, living room - 40-60%;
For adult bedroom - 40-50%;
for a children's bedroom - 45-60%.

To find out whether your health has worsened due to non-optimal levels of air humidity, you need to know how to measure the air humidity in an apartment, which changes even throughout the day. Dynamic changes are characterized by a change:

seasons;
weather conditions;
work heating devices and air conditioning systems;
features of the materials used in finishing the interior of the apartment and the facade of the house.

Important! Under the influence of the above factors, the humidity level can drop to 20%.

Therefore, it is worth understanding these subtleties in order to be able to normalize humidity at any time.

How to determine the level of humidity in a room

If there is excess moisture in the air or it seems to you that the microclimate in the apartment is too dry, take some measures to help normalize the optimal level of air humidity. But when starting such work, it is necessary to find out exactly how to calculate the value and what instruments can be used in the process. Of the whole list, only three methods are the most popular. Let's analyze them.

Hygrometer

The surest and easiest way is to use special device. You can measure the air humidity in an apartment using a hygrometer with an accuracy of 0.1%.

Important! These are multifunctional devices widely available on the market. Electronic models, in addition to humidity, can show other characteristics of the indoor microclimate: temperature, pressure, clock, etc.

Glass tumbler

This method is characterized by the least accuracy, but in the absence of the ability to diagnose air humidity using a more reliable device, it will do. To measure air humidity in an apartment without a device:

Fill a dry glass container with cold water.
Cool the contents of the glass until its temperature drops by 3-5 o C.
Place the glass on a cabinet in the room where the measurement is to be taken, away from heating appliances.
Evaluate the outcome by analyzing the process.
The walls of the vessel fogged up, but after about 10 minutes they became dry again - the humidity is extremely low.
After 5-10 minutes, the fogged walls have not dried, and the condensation rolls into large drops into the glass - the air humidity is increased.
The glass fogs up evenly, moisture does not evaporate from it, but does not roll down the walls - the moisture is within normal limits.

Thermometer

Do you know what device is used to measure air humidity in an apartment? Thermometer. This device works on the same principle as a psychrometer. The procedure is determined by four stages, during which:

Measure the air temperature using a traditional mercury thermometer. Record your results.
Wrap the tip of the thermometer with a damp cloth or cotton wool. After leaving it in this state for 10 minutes, check the indicators and evaluate the result. Record the temperature again.
Make the calculation: t 1 -t 2.
Use Assmann’s special psychrometric table and determine the humidity level by comparing the value with the number suggested in the manual for a specific type of room.

How to help increase humidity

Knowing how to measure air humidity in an apartment and how to do it correctly, you can restore an approximate picture of the real situation. Based on this, you can determine which measure of air saturation with moisture will be the most effective option.

Humidifier

This compact device is designed for humidification of rooms up to 150 m2. It works according to the following principle: hidden under the attractive-looking body is a small reservoir intended for water. Liquid is poured into it to a certain level, which gradually evaporates during the operation of the humidifier, thereby saturating the air with its molecules.

The entire range of purchased air humidification devices is divided into three volume groups. It is clear how you can measure the air humidity in an apartment, and what measures to take to increase it.

Traditional humidifiers

The mechanical device operates due to the built-in fan. The cooler forces air through a special reservoir of water, where it is saturated with water molecules and simultaneously cleaned of dust. As a result, you breathe clean, humidified air.

Important! A significant drawback of this type of device is the high level of noise it produces during the air filtration process. Ionization capabilities are also limited, because a traditional humidifier can only raise air humidity to 60%.

Steam humidifiers

The operating principle of such devices is reminiscent of the operation of a kettle. Inside the container, the water boils, and the steam formed during the reaction comes out. Some of the models of steam humidifiers are even equipped with special nozzles for inhalation, which allows you to use the device for health benefits.

Important! After measuring the air humidity in the apartment where the steam humidifier, the maximum humidity reaches 60%.

Users also highlight some disadvantages of the devices:

Hot steam with a temperature of up to 60°C, if handled carelessly, can cause burns and damage nearby objects and the surface of furniture.
Too noisy during operation.
Consumes a lot of electricity.

Ultrasonic humidifiers

A special membrane is built inside the device, which is responsible for converting water into steam. This device is less noisy than previous options. Availability additional function heating water in the process of turning it into steam allows you to disinfect the air without unnecessary effort, getting rid of germs.

These humidifiers operate on distilled water, which is poured into tanks with special cleaning cartridges. Filters must be replaced regularly.

Important! When choosing a device, do not forget to take into account the area of the room where the humidifier will be used. The device will be useless if placed in a room with an area larger than the recommended one and will not bring any benefit.

Traditional methods of increasing air humidity

You know how to measure air humidity in an apartment, but none of the described methods for increasing humidity are suitable for you... You can try to do it “grandmother’s way.” The following methods are suitable:

The simplest and most effective is a damp towel on the batteries. As the fabric heats up, it begins to release moisture, gradually humidifying the air in the bedroom. This procedure can be carried out as many times as necessary until the desired result is achieved.
A large number of indoor plants the apartment is good in itself. Green friends have a beneficial effect on the indoor microclimate, normalizing humidity levels.
Do not close the shower or bath door after taking a shower. water procedures. Excess moisture will come out of the bath, thereby saturating the air in other rooms.

How to effectively reduce indoor humidity

Using a device to determine the air humidity in the apartment, you noticed that the indicator is too high, which is also not good for health. Then the air in the room should be dehumidified due to the high concentration of moisture.

Air dryers

This device is designed to effectively absorb excess moisture. During the treatment process, air passes through a special evaporating membrane, which turns moisture into condensate. Drops of water are collected inside the device in a special container. The air is reheated and comes out, clean but devoid of moisture.

Important! When purchasing such a unit, do not forget to pay attention to the performance of the device and the maximum permissible volume of water that the dehumidifier can process per day.

Household dehumidifiers are capable of drying from 12 to 300 liters of water in 24 hours. They are:

Portable. This model is lightweight and portable and can be placed in any room.
Stationary. The dehumidifier is mounted on the wall, so it cannot be transported from one room to another.

Important! Such devices can even be used in refrigerated rooms. This will at least promote the formation of frost. When the tank is completely filled with water, due to untimely emptying of the tank, the dehumidifier automatically turns off.

Moisture absorbers

Such devices are convenient to use for rooms with large area. Using a special tablet inserted into the device, water is absorbed from the air. This technique is designed to drain an area of up to 30 m2.

Important! The only one, but significant drawback moisture absorber - the need for frequent controlled tablet changes.

This device is most often used during heating season when the air humidity is highest.

Important! This is a convenient and easy to use thing. It does not make noise during operation, is compact and not overpriced.

As you can see, determining the air humidity in an apartment is as important as maintaining it at optimal mode, important.

Effective folk methods

You can do without special equipment, saving money on the purchase, but if with high humidity you have to fight, try one of several effective methods which were used in the old days:

Ventilate the room regularly, regardless of weather conditions. This helps reduce moisture in the apartment. The more often you carry out the procedure, the better the air in the room dries.
Don't curtain the windows. Sun rays passing through the glass help dry the room.

Installing a modern air conditioner in a room will help regulate not only temperature, but also air humidity.

The problem of abnormal humidity in an apartment should be taken seriously. If there is a need to regulate its level, then this issue should not be delayed, since this will subsequently result, at a minimum, in the form of poor health of the inhabitants of the house. The presence of a device for measuring air humidity in the apartment will always keep the situation under control.

We regularly monitor the cleanliness of the apartment in which we live, regularly wash the floors, wipe the dust, wash the dishes, but we rarely think about the air humidity in the apartment. After all, this also affects a person’s well-being, the condition depends on it household appliances located in the house. It is extremely important to monitor the indicator in the apartment for favorable conditions life activity.

Determination of air humidity

It is very important to determine the humidity in the room. The degree of this indicator depends on several factors:

Climate in the region.
State of construction.
Operation of the premises.
Technogenic impact.

As a rule, for maximum approaching normality or creating comfortable conditions special devices are used to humidify the space in the house. In addition, there are special air conditioners that can independently measure the moisture level in a room and automatically maintain its condition.

Units

There are two types of humidity: absolute and relative. Absolute - means the amount of water vapor in a certain volume of air; it is measured in g/m3. Relative humidity is the mass of water vapor in a specific volume of air; measured as a percentage.

You can independently measure the level of humidity in the apartment using special devices, as well as using improvised means. For example, fir cone will help you find out what is the condition of the air in your apartment?. If the room is dry, the scales of the pine cone will open. You can also check this by monitoring the condition of the condensate. If the air is humidified in sufficient quantities, the evaporation process will proceed rather slowly.

Simple method

We can measure the level of moisture using a glass.

The steps are as follows:

Don't forget to time it! It will take approximately ten minutes to observe the behavior of the condensate.

If there is condensation on the walls of your container dries in such a short period of time, this means that the room is quite dry. If the walls of a glass or other dish remain wet, this is a good result, meaning that the air in the room is sufficiently humidified. If drops of condensation flow down the walls of the selected container, this is a sign that the air in the room is too humidified and the amount of water vapor is increased. This method will not give you complete accuracy and specific numbers, but it’s quite possible to see the lack or excess of moisture in this way.

Indoor devices

A device for measuring indoor air humidity is called a hygrometer. It is important to know what a hygrometer measures and how to use it correctly.

There are different types of hygrometer:

At home, electronic, hair and psychometric hygrometers are most often used. Considered one of the easiest to use hair hygrometer. The principle of its operation is simple: just look at the arrow indicating the level of humidity, the indicator of which is an ordinary hair. That's why the hygrometer is called a hair hygrometer. This device is highly sensitive and is usually used at home.

The most reliable the measurement method is a psychrometer. The principle of its operation is based on the fact that the presence of moisture in the room lowers the temperature. The thermometer has two thermometers: dry and wet. In order to determine the humidity level, you simply need to find the difference between these two temperatures. The percentage we need is determined by crossing two lines: the temperature measured by a dry bulb thermometer and the difference in readings. Find the temperature difference between dry and damp room can be calculated using a special psychrometric table.

One of the modern determinants of this type is considered to be an electronic or digital hygrometer. Determination occurs by measuring resistance electric current when the electrolyte humidity changes. This hygrometer is quite convenient, but it requires connecting the device to an electrical outlet. Sometimes it runs on batteries.

There are also room humidity meters that can have a built-in hygrometer; the device can measure both humidity and temperature in the room. Now you know what instruments are used to determine air humidity.

Even if you were able to measure an indicator using one of the above methods, you need to know what the optimal indicators are to focus on. For example, a humidity level of 45% will be very comfortable for a living space, but, on average, the indicator may indicate a designation in the range from 30 to 60%. If you do not know how to measure air humidity at home, use the special device described above.

Methods of moisturizing

In order to bring the humidity level in the room closer to normal, you can do the following:

Try one or more of their suggested methods and strive for optimal performance air humidity in the apartment, because this is very important for your health.

Attention, TODAY only!

To determine the absolute humidity of the air, two types of instruments are used, called a psychrometer (from the Greek Psychros - cold): the August station psychrometer and the Assmann aspiration psychrometer.

The principle of psychrometry is to determine the readings of two thermometers, the reservoir of one of which is moistened. Moisture evaporating from at different speeds depending on humidity and air speed, it takes heat away from the thermometer, so wet bulb readings will generally be lower than dry bulb readings.

Station psychrometer Augusta consists of two identical alcohol thermometers, the reservoir of one of which is wrapped in a piece of thin hygroscopic fabric, one end lowered into a glass of distilled water room temperature. Due to the evaporation of water, the temperature of the wet bulb will be lower than the temperature of the second (dry) bulb. Thermometer readings are taken 15 minutes after one of them is moistened.

Hygrometer(from the Greek hygros - wet) - a device for directly determining the relative humidity of the air. There are different types of hygrometers, but the most common of them are hair hygrometers, based on the ability of hair, due to its hygroscopicity, to lengthen in a humid atmosphere and shorten in a dry atmosphere.

Hygrograph. The operating principle of a hygrograph is similar to that of a barograph and thermograph. The device is used to record continuous measurements of relative humidity and consists of a sensing element - a tuft of defatted hair, a rotating drum with tape, connecting levers and a pen with ink.

Methods for determining air humidity

Calculation of absolute humidity when working with the August psychrometer is carried out using the Regnault formula:

K = f-Q (t-t,)-B,

where K is the desired absolute humidity, g/m3;

f - the maximum voltage of water vapor at the wet-bulb temperature is determined from the table (see note);

Q is the psychrometric coefficient, which is assumed to be equal for an open atmosphere 0,00074, and for indoor air - 0.0011;

t - dry bulb temperature;

ti is the wet bulb temperature;

B - barometric pressure at the time of the study, mm Hg. st;

0.5 - constant psychrometric coefficient;

755 - average barometric pressure, mm Hg. Art.

Table No. 2

ELASTICITY OF SATURATED WATER VAPOR /selectively/

Air temperature in degrees	Water vapor tension in mmHg.	Air temperature in degrees	Water vapor tension in mmHg.

Calculation of relative humidity: Converting the found absolute humidity to relative humidity is carried out using the formula:

where R is relative humidity, %;

K - absolute humidity, g/m3;

F - maximum humidity at dry bulb temperature (see table in note).

If the observation is carried out in a room where the air moves uniformly, then to make it easier, you can use special tables in which the corresponding relative humidity is directly found from the temperature of the dry and wet thermometers.

Developing students’ skills in organizing and conducting preventive (hygienic) measures, conducting and promoting healthy image life, skills to use factors environment, in this case physical properties air (temperature, humidity, atmospheric pressure), for health purposes, is based on a conscious understanding of the connection between human health and the environment, factors and living conditions, work activity, therefore students must have information on mastering the methodology of preventive medicine, acquire hygienic knowledge and skills in assessing the impact of environmental factors on human and population health.

Topic: “sanitary and hygienic assessment of the microclimate of premises (temperature, humidity, atmospheric pressure) » reveals issues related to the basic concepts of microclimate, heat exchange and the factors that determine and regulate them. Hygienic requirements to the temperature and humidity conditions of the premises. Indicators, standards.

Indoor air humidity is one of the most important indicators that determine the microclimate in the house. If temperature and speed air flow You can approximately determine by personal feelings, then you can’t say how much water in the volume of the room “by eye”. How to determine air humidity? To do this, use either a device for measuring indoor air humidity or improvised means.

They all have individual precision and order of use.

Humidity is the content of water vapor in the air. The comfortable existence of living organisms, the possibility of the development of living nature, and the safety of materials are possible only with certain values of this parameter.

It happens:

absolute;
relative.

Absolute shows the amount of water vapor in a certain volume. Most often measured in g/m3. It has no practical significance, since it is impossible to determine whether the humidity is normal or not, knowing that the amount of water vapor is 10 g/m3.

Maximum performance change depending on the air temperature. At – 30 o C this parameter is equal to 0.29 g/m 3 , at 0 o C – 4.8 g/m 3 , at + 30 o C – 30.4 g/m 3 . The maximum value is reached at a temperature of 100 o C (boiling point of water) and is equal to 598 g/m 3.

Relative is determined by dividing the current humidity value by the maximum possible at certain temperature, multiplied by 100. Humidity is measured as a percentage. It is widely used in weather forecasts, the composition of food products, and the characteristics of industrial, warehouse and residential premises.

What are the dangers of insufficient and excess moisture?

It's flowing through the windows

Excessive moisture in the air literally has a deplorable effect on the condition of the objects around us. Inner surface The windows are covered with drops of moisture, which flows onto the windowsill. Bed linen, clothing, fur products are purchased bad smell dampness, they are inconvenient and unpleasant to use.

Food spoils and is impossible to eat. Enclosing structures and finishing become covered with mold. Its spores spread through the air and can cause allergic reactions and a sharp decrease in immunity. A person gets sick more often, and the recovery process takes longer.

Like in the desert

Lack of moisture in the air at low temperatures leads to hypothermia and dehydration due to increased sweating.

In such air, the level of static electricity increases and the amount of dust increases. Mucous surfaces dry out human body. There is a sore throat, dryness in the nasal cavity, and burning in the eyes.

We use devices

The easiest way to measure air humidity is with a device. It's called a hygrometer. According to the principle of action it happens:

by weight;
hair;
film;
electrolytic;
ceramic;
condensation;
electronic;
psychrometric.

In domestic conditions, psychrometric, hair, and electronic hygrometers are used. To obtain reliable results, know how they measure air humidity.

The most reliable

Determining air humidity using a psychrometer (from Greek - cold) is not difficult. The operation of the device is based on the fact that the presence of moisture lowers the temperature. The panel is equipped with 2 thermometers and a psychrometric table. The first thermometer is dry, the second is wet. To measure, you need to find the difference in temperature readings. The table shows the air temperature measured by a dry thermometer vertically and the difference in readings horizontally. The intersection of these two lines shows the relative air humidity as a percentage.

The psychrometer is a reliable, fairly simple device for determining humidity, providing accurate information. Requires constant monitoring for the presence of water in the wet thermometer container. Allows you to simultaneously monitor air temperature and humidity.

Simplest

The oldest and simplest device for measuring humidity is the hair hygrometer. How to find out air humidity using it?

Just look at the arrow, under which there is a scale with divisions every 1%. The principle of operation is based on changing the linear dimensions of objects depending on their saturation with moisture. For such an item, ordinary fat-free hair is used. This is where the name of the device “hair” comes from.

The disadvantage is the large measurement error (about 10%). The advantages are:

high sensitivity;
quick response to changes in humidity;
large measurement range - from 30 to 100%.

Used to determine the relative air humidity in residential areas. Often it is a beautifully designed piece of furniture.

Most modern

How is humidity measured in interiors? modern classics and hi-tech? Modern design requires modern devices. One of these is a digital (electronic) hygrometer. It is based on measuring the resistance of electric current when the humidity of the electrolyte changes.

The disadvantage of this air humidity detector is the need to connect to an electrical network or use batteries.

The liquid crystal display also displays time and temperature. There is a backlight for use at night. The update rate of readings is from 10 to 20 seconds. The error in measuring indoor air humidity is 5%.

Themselves with a mustache

How to measure humidity if there is no device, and there is no need to buy it due to rare use? Ingenuity, experience of generations, simple objects that are in every home will come to the rescue.

Burn, burn my candle

Introducing the old-fashioned way to determine the humidity in a room. To do this, it is enough to make a moisture meter from a simple candle and a match. Before measuring air humidity:

close the doors leading to adjacent rooms;
ensure there are no drafts;
light a candle;
watch the flame.

If the flame sways and the halo has a crimson color, there is a lot of water vapor in the air. If the combustion is evenly vertical and the flame is orange-yellow, the presence of water vapor is normal.

Water, glass, refrigerator

This method makes it possible to measure air humidity at home. This device has only three moisture readings:

redundant;
normal;
insufficient.

Before checking the humidity in the apartment, pour plain tap water into a glass beaker. cold water. Place in the refrigerator for 5-6 hours. The water temperature should be 6 o C.

You can measure it either using outdoor thermometer or a bathroom thermometer. Then place the glass on the table in the room, 1 meter away from the windows and walls. After 10 minutes, evaluate the result:

condensation on the outer walls of the glass has concentrated into drops that flow onto the table - excess;
the physical state of the condensate has not changed - normal;
the condensate has evaporated or it has become significantly less - insufficient.

Make your own psychrometer

To determine air humidity, you can use an ordinary room temperature mercury thermometer. It can be used to measure air humidity using a psychrometric method. Before measuring the humidity in the room, prepare an ordinary rag and water.

The procedure for checking the presence of water vapor in the air volume with your own hands is as follows:

measure the air temperature in the room and record it;
wrap the mercury flask of the thermometer with a damp cloth;
wait 10 minutes;
take and record thermometer readings;
calculate the difference between dry and wet measurements;
download the psychrometric table;
find the humidity level in the room.

Such an air humidity meter does not take up much space, does not require additional costs, and provides the necessary measurement accuracy.

Normal indicators

It is not enough to determine the air humidity in the room. It is also necessary to know whether the data obtained is normal. The optimal and most comfortable value is 45%. In this case, the acceptable range of changes in air humidity in the apartment is 30 – 60%. In different ways functional purpose indoors it is recommended to maintain different quantities water vapor:

hall, dining room, living room, kitchen, bathroom – 40-60%;
bedroom for adults and teenagers – 40-50%;
children's room - 45-60%;
office - library - 30-40%.

Achieving different indicators of the presence of moisture even in small rooms is quite troublesome. First of all, you need to ensure the humidity level. Most modern living spaces lack it due to large quantity heating and electrical appliances.

This makes you feel worse and reduces your performance. Children suffer the most from this.

We bring it to normal

To ensure a comfortable stay, it is necessary to regulate the relative humidity of the air. To do this you need:

Ventilate the premises regularly, at least twice a day. It is best to do this after waking up and before going to bed. In winter, it is better to carry out short-term ventilation with wide open window to prevent cooling of walls and floors. In summer, when the amount of moisture outside is insufficient, you can open the windows not widely for a long time.
Increase the number of indoor plants. Moistening occurs due to the evaporation of moisture from the soil surface. Wrinkled, drooping, dried leaves will indicate a lack of air moisture.
Set up an aquarium. The evaporation of water from its surface greatly humidifies the air. This is noticeable even without measurements. If you don’t want to get involved in aquarium farming, you can place water containers in your apartment. Not so aesthetically pleasing, but very practical.
Carry out regularly wet cleaning. The absence of dust will allow more moisture is in suspension.
Buy a special device for humidifying the air. This is especially true if there are infants and young children.
Spray water using a spray bottle for watering plants or ironing clothes.

AQUARIUM AND AIR HUMIDITY

Whether you choose one method or use a set of measures does not matter. The main thing is that the temperature and humidity indicators are within normal limits.

We need the right humidity, humidity is very important to us. This main conclusion can be drawn by reading the article. Maintain the air humidity in the apartment within normal limits and take care of your own health.

The principle of psychrometry is to determine the readings of two thermometers, the reservoir of one of which is moistened. Moisture, evaporating at different rates depending on humidity and air speed, removes heat from the thermometer, so wet-bulb readings will generally be lower than dry-bulb readings.

Station psychrometer Augusta consists of two identical alcohol thermometers, the reservoir of one of which is wrapped in a piece of thin hygroscopic fabric, one end of which is lowered into a glass of distilled water at room temperature. Due to the evaporation of water, the temperature of the wet bulb will be lower than the temperature of the second (dry) bulb. Thermometer readings are taken 15 minutes after one of them is moistened.

Hygrometer(from the Greek hygros - wet) - a device for directly determining the relative humidity of the air. Exist Various types hygrometers, but the most common of them are hair ones, based on the ability of hair, due to hygroscopicity, to lengthen in a humid atmosphere and shorten in a dry atmosphere.

Methods for determining air humidity

Calculation of absolute humidity when working with the August psychrometer is carried out using the Regnault formula:

K = f-Q (t-t,)-B,

where K is the desired absolute humidity, g/m3;

f - the maximum voltage of water vapor at the wet-bulb temperature is determined from the table (see note);

Q is the psychrometric coefficient, which is assumed to be equal for an open atmosphere 0,00074, and for indoor air - 0.0011;

t - dry bulb temperature;

ti is the wet bulb temperature;

B - barometric pressure at the time of the study, mm Hg. st;

0.5 - constant psychrometric coefficient;

755 - average barometric pressure, mm Hg. Art.

Table No. 2

ELASTICITY OF SATURATED WATER VAPOR /selectively/

Air temperature in degrees	Air temperature in degrees	Water vapor tension in mmHg.	Air temperature in degrees	Water vapor tension in mmHg.

Calculation of relative humidity: Converting the found absolute humidity to relative humidity is carried out using the formula:

where R is relative humidity, %;

K - absolute humidity, g/m3;

F - maximum humidity at dry bulb temperature (see table in note).

Developing in students the skills of organizing and carrying out preventive (hygienic) measures, maintaining and promoting a healthy lifestyle, the ability to use environmental factors, in this case the physical properties of air (temperature, humidity, atmospheric pressure), for health purposes, is based on a conscious understanding of the relationship human health with the environment, factors and living conditions, labor activity Therefore, students must have information on mastering the methodology of preventive medicine, acquire hygienic knowledge and skills in assessing the influence of environmental factors on human and population health.

Topic: “sanitary and hygienic assessment of the microclimate of premises (temperature, humidity, atmospheric pressure) » reveals issues related to the basic concepts of microclimate, heat exchange and the factors that determine and regulate them. Hygienic requirements for temperature and humidity conditions of premises. Indicators, standards.

How to choose a device for measuring air humidity

We all understand how important it is to support optimal humidity indoors, especially where the child lives. After all, his health depends on it. There are too many allergens in the dry, dusty air of apartments, and a damp room can cause your baby to develop chronic diseases. But how to measure indoor air humidity? This is what we will talk about today.

How to measure humidity with a glass

Of course, if you don’t have a special device, you can use the old method. To do this, a glass filled with water must be placed in the refrigerator until the water cools to a temperature of -5°C (these are average values for refrigeration chamber). Then put this homemade device to measure the air humidity in the room away from the battery and observe it. The walls of the glass will fog up, but if after five minutes they turn out to be dry, the room insufficient humidity. If after this time they still become foggy, the indicators are normal. But water flowing down the walls in streams signals that the room is too damp.

But you understand that such indicators are too approximate. In order to establish accurate numbers, a hygrometer is needed. There are several types of these devices.

Device for measuring air humidity: thermohygrometer

This is a rather complex device that measures not only humidity, but also temperature in the room. In addition, the thermohygrometer demonstrates indicators measured at different ends of the room: where the sensor is attached, and at the installation site of the device itself.

The cable of the digital thermohygrometer has a length of 1.5 m, and the range of indicators is from 0 to 90%. Wireless devices, among other things, are also equipped with an alarm function in case of critical humidity in the room.

Working principle of hair and film hygrometer

The hair hygrometer is created on the basis of synthetic fat-free hair, or rather its ability to change its length depending on the air condition. It is stretched between the end of the arrow and the spring. Fluctuations in its length cause the hand to move across the dial. This device for measuring air humidity is capable of determining it over a wide range (from 0 to 100%), it is easy to use, and can be mounted on a wall.

A film hygrometer has a sensing element made of organic film. It stretches or contracts with changes in humidity. Changes in the position of its center are transmitted to the arrow.

Under low temperature conditions, these two kinds of hygrometer are the main instruments for measuring humidity levels.

How to make the right choice

It is up to the buyer to decide which hygrometer to choose: wall-mounted, table-top, mechanical or digital. But when purchasing, you must follow several rules.

First of all, decide how accurate the data you need, because there are models that can measure absolute indicators, and those that demonstrate relative results.
Think about where you will place or hang your air humidity meter.
Check its contents: a quality device must have indicators and a psychometric table.
Don't forget the receipt. This way you can always return low-quality goods.

Condensation hygrometer. Hygrometer for measuring air humidity

A widely used instrument for measuring air humidity (and other gases) is a condensation hygrometer. Its operating principle is to measure the temperature, called the dew point, at which moisture begins to condense from the air.

What is air humidity

A hygrometer measures the moisture content in the air, which can be expressed as an absolute or relative value. The first of them simply gives the mass of water vapor in 1 cubic meter. m of air at a given temperature. But the second shows how close water vapor in the air is to a state of saturation, i.e. to dynamic equilibrium with its liquid phase - when there is no evaporation or condensation. It is equal to the ratio of the measured absolute humidity of the air to its absolute humidity in a state of saturation. When water vapor in the air is saturated (again, at a given temperature), the relative humidity of that air is 100%. In air with unsaturated water vapor it is correspondingly less.

How does a condensation hygrometer work?

The principle of operation of any device for determining air humidity, as a rule, is to measure some other quantity, such as temperature, pressure, mass, or mechanical and electrical changes in the substance that absorbs moisture. By appropriate calibration and calculation, these measured values can lead to the determination of absolute or relative humidity. A very important role in this process is played by the temperature at which steam saturation occurs, called the dew point. Typically modern electronic devices to determine air humidity, measure exactly this temperature or changes in electrical capacitance or the resistance of various moisture-absorbing substances, which are then converted (automatically) into humidity values.

Condensation hygrometer: device

His work is based precisely on measuring the water vapor content in the air using the dew point method. This method involves cooling the surface, typically a metal mirror, to a temperature at which the water on the surface of the mirror is in equilibrium with the vapor pressure of the water in the gas sample above the surface. At this temperature, the mass of water on the surface of the mirror neither increases (if the surface is too cold) nor decreases (if the surface is too warm), i.e. the steam above the mirror is in dynamic equilibrium with the water condensate on the mirror (the steam is saturated).

This mirror is made from a material with good thermal conductivity (such as silver or copper) and is coated with a layer of an inert metal such as iridium, rubidium, nickel or gold to prevent tarnishing and oxidation. The mirror is cooled using a thermoelectric cooler (Peltier effect) until condensation begins to form. A beam of light, usually from a solid-state broadband light-emitting diode, is directed at the mirror surface, and a photodetector monitors the reflected light, the flux of which is maximum when there is no condensation on the mirror.

Method of operation of a chilled mirror hygrometer

When dew drops form on the mirror surface, the reflected light is scattered. At the same time, its flow entering the photodetector decreases, which leads to a change in the output signal of the latter. This in turn is controlled by an analogue or digital thermoelectric cooler control system which maintains a stable mirror temperature at the dew point. With a properly designed system, the mirror is maintained at a temperature where the rate of condensation is exactly equal to the rate of evaporation of the dew layer. An accurate miniature platinum resistance thermometer (PRT) mounted in the mirror measures its temperature at this point, which is automatically converted into a humidity reading.

The hygrometer for measuring air humidity of the design in question also includes a vacuum pump to pump in the analyzed portion of gas, and additional elements filtration in dirty conditions.

Advantages of the hygrometers under consideration

Similar devices based on simple principle work, with a wide measurement range, high accuracy and stability of readings, are widely used in industry and in scientific research. Typical condensation hygrometer, unlike many other humidity sensors, can be made to be very stable, virtually resistant to wear, minimizing the need for recalibration. A dew point humidity hygrometer can measure dew point humidity over a temperature range of 100°C to a minimum of -70°C. In this case, the measurement accuracy is tenths of a degree.

Many hygrometers of this design are equipped with microprocessor control and, in combination with a resistive temperature sensor, are capable of calculating and displaying on an external indicator any desired humidity parameters in addition to or instead of the dew point. In addition, these devices allow the transfer of results using wireless technologies. Naturally, such devices are widely used as part of various industrial systems automated data collection and management of relevant technical processes.

How much could a hygrometer like this cost? Its price, of course, is determined mainly by the set of implemented functions, depending on the availability and complexity electronic system device control. Thus, a stationary condensation hygrometer, similar in appearance to a digital oscilloscope, costs at least $4,000. Particularly “advanced” models can cost more than $10,000. You can also find a fully functional portable hygrometer on the market. Its price ranges from 1 to 2 thousand dollars.

Disadvantages of condensation hygrometers

While the hygrometer system under consideration is considered the most effective in the measurement process, its disadvantage is the inevitable contamination of the parts of the measuring path during operation.

Hygrometers equipped with cooled mirrors tend to increase measurement inaccuracy due to the presence of soluble and insoluble contaminants deposited on the mirror. Insoluble particles affect optical characteristics mirrors Moderate dustiness or the appearance of insoluble particles on the mirror provide the presence of concentration centers where dew or frost can form, thereby increasing the response time of the device. Soluble impurities affect the vapor pressure from condensed moisture on the mirror, which shifts the dew point. Modern measuring hygrometers (at least there are more of them) complex models) include “self-check” functions that allow the device to detect and respond to contamination by making appropriate adjustments to its moisture calculation algorithms.

Regardless of the availability of such capabilities, almost all hygrometers under consideration require periodic inspection and cleaning.

Maintenance of chilled mirror hygrometers

What does the user's manual recommend in this regard? The hygrometer, which is sensitive to contamination, must be cleaned periodically to ensure consistent measurement results, although this may increase maintenance costs. Inspection of the instrument mirror is usually performed using a built-in microscope, and maintenance is performed manually after opening the measuring compartment.

If the surface of the mirror is cleaned at the frequency required in its operating instructions, then the accuracy of the measurements can be maintained. Convenient access to the mirror surface for cleaning is usually provided by a hinge between the optical components and the mirror. On the market now you can find any condensation hygrometer the consumer needs. The photo below shows an example of its execution.

Application of hygrometers in metrology

A properly designed and operated chilled mirror hygrometer provides humidity measurements with orders of magnitude greater accuracy than other popular humidity meters. Inherent measurement accuracy, especially when equipped with a platinum resistance thermometer for temperature measurement, a mirror and a microscope medium power for monitoring the condition of the mirror, making it ideal for metrological measurements. The possibilities of transmitting information via wireless digital communication channels open up ample opportunities the use of such hygrometers in global systems for collecting and processing meteorological information.

Use in factory laboratories and contaminated environments

These devices for determining air humidity are ideal for measuring its absolute value in factory climate laboratories. They are often used as standards to monitor the accuracy of other instruments, such as relative humidity sensors used to control climate test chambers.

The stability of the materials used in the construction of these hygrometers, as well as the ability to repeatedly clean them, make the instruments suitable for very long service in environments with the presence of most pollutants without loss of calibration. This stability of performance makes them suitable for use in gas streams where high levels contaminants in gas samples have an irreversible effect on less stable types of humidity sensors harmful effects. For example, this type of hygrometer is widely used to control the dew point during thermal hardening of surfaces metal products V air environment with special additives. In such cases, providing easy access to the mirror for cleaning is especially desirable.

Moisture sensitive production

Specialized packaging processes required in the production of pharmaceuticals, films, coatings and other products are often monitored by chilled mirror hygrometers. Again, their choice in this case is influenced by the stability of measurement accuracy and long service life. In addition, since these processes are generally less sensitive to instrumentation costs, high price hygrometer data is not a determining factor in choosing a humidity monitoring scheme.

High temperature gases and their dew points

This type of hygrometer is often chosen to measure dew point temperatures above ambient temperature. Chilled-mirror instruments were used as early as 1966 to monitor the hydrogen fuel cells of Apollo rockets operating at 250°C and 700 psi. With today's thermoelectric mirror cooling technologies, dew points of up to 100 °C (and higher, provided above atmospheric pressure) are easily measured. In such cases, all surfaces of the hygrometer measuring compartment in contact with the gas sample must be at a temperature above the highest expected dew point, otherwise condensation will occur on these surfaces and the measurement will be erroneous.

In hygrometers designed to measure the dew point of high-temperature gases, it is common practice to use electric heaters with a thermostat to maintain the temperature of the walls of the measurement compartment above the highest expected dew points. Solid-state optical components such as LEDs and detectors are maintained at their rated operating temperature (typically 85°C) to prevent them from breaking and causing the hygrometer to fail. This can be achieved by thermally isolating these components from the heated measurement compartment.

What is the name of the device for measuring air humidity?

Resilient child

I know two principles for measuring air humidity.
1. Comparing the readings of two thermometers, one of which is wrapped in a wet wick, which does not dry out because its end is immersed in water, and finding the percentage of humidity according to the table (the smaller the difference in the readings of the dry and wet thermometer, the higher the humidity). Such a device is called a psychrometer.
2. Measuring the length of the hair (it is wound at one end on a reel with an arrow and when the humidity changes, it rotates, shortening or lengthening). This is a hygrometer.

V ikh r

Hello!
"PSYCHROMETER" is a device for precise definition air humidity exists (see figure). It consists of two identical thermometers - “dry” and “moistened” (with distilled water) using a wrapped cambric, the end of which is lowered into a glass. This is professional very accurate meteorological instrument for measuring temperature and air humidity, installed in a special psychrometric booth (cm) at a height of 2 m from the soil surface. This standard is international and adopted by the WMO (World Meteorological Organization) and such booths are installed at tens of thousands of weather stations around the world.
A pair of dry-wet thermometers allows you to measure air humidity with high accuracy. Due to the fact that evaporation occurs from the surface of the wetted thermometer, the heat spent on evaporation lowers its temperature (“psychro” - cooled). The difference in readings will be greater, the lower the air humidity (the higher the evaporation rate), which is taken into account by calculating humidity depending on this difference and value atmospheric pressure(the rate of evaporation also depends on it). In life, for operational work they do not use calculations using formulas, but with special “Psychrometric tables”. It is clear that if the air is saturated with water vapor, then evaporation from the wet thermometer will stop and the temperature of both thermometers will become the same.
At negative temperature air down to -10 C, they also use the readings of a psychrometer (based on ice or unfrozen water), and at lower temperatures, humidity is determined using a HYGROMETER (hair or film), the principle of which is that defatted hair or film changes its size with changes in humidity and this is transmitted to the arrow. But this device is less accurate and is calibrated using a psychrometer.
All the best.