How to determine the humidity in the apartment: available methods

The well-being and health of its owners depends on the state of the microclimate in the apartment. The level of humidity is one of the main indicators characterizing the parameters of the air that people breathe in the room. Therefore, it must be periodically monitored. This indicator should remain at the level established by sanitary and hygienic standards.

Therefore, the question arises before the residents of the house, how to determine in an apartment. Various methods are used for this. Even without special devices, everyone can measure the level of humidity in the room. Existing methods will be discussed in detail below.

Why measure humidity levels?

Studying the question, it is necessary to consider first of all what this indicator affects. This will assess the importance of such a procedure.

The humidity in the room should not be higher or lower than the specified range. Being indoors, a person may not immediately notice the inconsistency of the surrounding conditions with the requirements of sanitary and hygienic standards. But over time, such violations can affect the health of the owners.

Asthma and allergies develop due to high humidity. A reduced value of this indicator leads to disturbances in the state of the mucous membranes, a decrease in immunity, and skin aging. Children are especially sensitive to unfavorable environmental conditions. Therefore, parents are simply obliged to monitor the level of humidity in their apartment.

Permissible value

Studying the question how to determine the humidity in the apartment, you should consider the allowable values ​​of this indicator. Note that humidity is measured as a percentage. This is a fraction of the primary mass volume of moisture.

Experts claim that optimal value indicator for the premises is 45%. In this case, its deviation in both directions is allowed. Thus, the humidity in the apartment should not go out of the range from 30 to 60%.

There are norms that determine the parameters of air depending on the purpose of the room. In the living room or dining room, the range is 45-60%, and for the bedroom of adults - 40-50%. In the children's room, the humidity should be higher. Normally, it is at the level of 45-60%.

But for a library or an office, it is important to maintain this figure at the level of 30-40%. This will save documents, books from premature destruction. In a kitchen or bathroom, humidity can range from 40 to 60%.

Effects of high humidity

Going deeper into the topic how to determine the humidity in the apartment, one should clearly understand the consequences of the deviation of this indicator both in one direction and in the other. Inconsistencies are a warning sign.

The first sign of high humidity in the apartment is condensation on the windows. At the same time, all things, furniture in the room are affected by dampness. Then a specific musty smell appears, and in the corners, on interior items, a fungus begins to develop. Mold is an unsafe neighbor for humans. It causes serious deviations in well-being, causes a number of ailments.

The consequences of high humidity can be allergies or even asthma, a decrease in the functions of the immune system. Children sometimes have diathesis. Headache, diseases of cardio-vascular system are also the result of an unsuitable microclimate. Bronchitis, otitis also develop in similar conditions. Cancer cells also grow faster in high humidity.

Effects of dry air

From the above it follows that everyone should understand how to find out the humidity in the apartment. The low value of this indicator is also dangerous. Especially often this situation develops in the hot season.

First of all, all dust, wool and other particles begin to rise and move freely with air masses. They do not settle on interior items and freely fall into human body.

Moisture from the skin begins to evaporate intensively. This causes a rapid cooling of the body. Also, the mucous membranes of the body begin to dry out. Protection of organs from harmful microorganisms is reduced. There is fatigue, drowsiness.

Dry air has a particularly negative effect on the children's body. Such a microclimate in the room leads to disruption of the kidneys, and also contributes to the development of dysbacteriosis. Moreover, even an adult organism is subject to such influence.

Hygrometer

A hygrometer is the most reliable instrument for measuring indoor humidity. Its error should not be more than 1%. On sale are multifunctional devices that also show room temperature, pressure, etc.

However, many owners are interested in the question, how to determine the humidity in the apartment without a hygrometer. After all, this device is not always at hand. Buying a hygrometer is still worth it over time. But other methods can be used to estimate the humidity of the air in the room. This will allow you to quickly take measures to eliminate serious deviations.

Measuring humidity with a thermometer

One way to measure indoor humidity without a hygrometer is to use a thermometer. This is an easy procedure. How to determine the humidity in the apartment using a thermometer, should be considered in more detail.

There is a certain course of action. You will need a regular mercury thermometer. With it, you must first measure the ambient temperature. It is better to write down the testimony so as not to forget.

Next, the tip of the thermometer should be wrapped with wet gauze or cotton. After 10 minutes, the instrument readings should also be recorded. The second value is subtracted from the first indicator. Next, according to the Assman psychometric table, you need to find the level of humidity in the room.

Glass of water

Another simple method is the technique with a glass of water. This approach is not very accurate, but it will help to identify significant deviations in the microclimate of the room. , discussed below.

In the house there will always be the necessary items for research. Glass beaker needs to be filled cold water. The contents should have a temperature of 3-5 °C. The glass must be placed in the room. There should be no heating devices nearby.

If the walls of the glass are fogged up, but after 10 minutes. dried out, the humidity level in the room is very low. If, after this period of time, drops of a misted glass flow from its surface, the indicator is very high. If the humidity is within allowable rate, the condensate is not collected in drops and does not flow from the glass.

Solution

Having considered how to determine the humidity in the apartment without devices, you should learn the methods of dealing with the discrepancy between the microclimate and the standards. With a lower value of the indicator, special humidifiers are used. They are presented in a wide range for sale. You can also put a damp towel or a container of water on the battery. Care should also be taken to dilute a sufficient amount indoor plants.

If the humidity is high, you can purchase special devices. They use various methods to remove excess water from the air. Experts also advise regular airing. This must be done even in rainy weather. Some rooms may require an extractor fan.

Having become familiar with the methods how to determine the humidity in the apartment, you can quickly and accurately assess the state of the microclimate in the room. This will allow you to take appropriate measures in time and return the indicator within the limits of the standards. The health and well-being of people living in a house or apartment depends on this. Therefore, special attention should be paid to the issues of measuring humidity.

The air we breathe is one of the main factors affecting our health. In this article, we will talk about how to measure the humidity in a room so that you can always stay in good health and feel cheerful, comfortable and full of energy.

Optimum air humidity in the apartment

The air that is comfortable for the whole body should have a humidity within 45%. But for each room, this parameter can fluctuate within acceptable limits:

• Office and library - 40-45%.
• Dining room, bathroom, kitchen and living room - 40-60%.
• Adult bedroom - 40-50%.
• Children's room - 45-60%.

• change of seasons;
• weather change;
• operation of heating devices and air conditioning;
• features of materials used for interior and facade decoration.

Therefore, you need to know how to measure the humidity in the room in order to maintain the optimal mode.

Important! These factors can reduce the level of humidity by at least 20%.

The danger of high humidity

A visible sign of a violation of the level of humidity in its greater direction in the room is foggy “weeping” windows. Things acquire excessive dampness, an unpleasant musty smell appears, mold begins to develop in the corners.

As you know, mold fungus is a microorganism that is not safe for human health. It can cause serious illnesses:

• Allergies that turn into asthma.
• Decreased immunity.
• Diathesis in infants.
• Frequent headaches.
• Rapid development of cancer cells.
• Otitis.
• Bronchitis.
• Diseases of the cardiovascular system.

And this is only the beginning of the list of those terrible health disorders that high humidity can lead to. Therefore, it is necessary to be able to determine the humidity of the air at home in order to eliminate such problems.

Important! The process of recovery at air humidity above 60% is long and incomplete.

Dry air danger

The problem of dry air is especially relevant in the hot season, when the ambient temperature rises significantly. This leads to the fact that dust, plant pollen, animal hair and other allergens easily move around the rooms and do not settle on pieces of furniture. Thus, it is easier for them to enter the human body through the respiratory tract and cause a serious reaction. This is especially dangerous for small children.

Important! When staying for a long time in a room with dry air, moisture evaporates from the skin. This leads to cooling of the body.

In addition, dry air causes the mucous membranes of the respiratory tract to dry out, which makes the organs vulnerable to the action of microbes. It is difficult to work in a room with dry air, even for a very efficient person, as the body quickly gets tired. A person constantly experiences a feeling of drowsiness. Increased static electricity is also a characteristic phenomenon in such rooms.

Important! Pediatricians claim that dry air is the cause of the change normal operation kidneys and the development of dysbacteriosis even in healthy children.

How to determine the humidity in the apartment?

If the air in your apartment is too humid or vice versa - dry, then you need to take some measures to establish its optimal level. But first you should familiarize yourself with how to determine the humidity of the air at home. There are several ways to do this.

Hygrometer

Using this device is the easiest and surest option. When choosing a hygrometer, you should pay attention to its accuracy. The measurement deviation should be no more than 1%.

Important! Such devices on the modern market are multifunctional devices. In addition to measuring humidity, they can display temperature, pressure, hours, and other data.

glass cup

This method is not accurate, but if necessary, it will help to understand the values ​​\u200b\u200bof humidity. The necessary items for the implementation of such a task are probably in the arsenal of every housewife.

Procedure:

1. Fill a glass vessel with cold water.
2. Cool the contents of the glass to 3-5 degrees.
3. Place the vessel in the room away from heating devices, and analyze the result.

Result evaluation:

• The walls of the vessel were fogged up, but after about 10 minutes they were dry. This result indicates an extremely low level of humidity.
• The misted walls of the glass have not dried up even after 5-10 minutes and the drops flow into the glass. Such indicators indicate high humidity.
• The condensate formed on the walls of the glass container has not evaporated, but it does not flow down in large drops either. This effect indicates that the moisture in the air is within the normal range.

Thermometer

Measurement of air humidity with a thermometer is carried out according to the principle of operation of a psychrometer.

Procedure:

1. First you need to measure the air temperature using a standard mercury thermometer. Record your readings.
2. Wrap the head of the device with damp wet cotton wool or gauze and after 10 minutes evaluate the thermometer readings.
3. Subtract from the dry-bulb temperature number the wet-bulb reading number.
4. Find the resulting difference according to the values ​​​​of the special Assmann psychometric table, determining the level of air humidity in the room you need.

How to increase air humidity?

Knowing how to check the humidity in the apartment, you will see, albeit not an accurate, but approximate picture of the real situation. Thanks to this, you can take the following measures to saturate it with moisture.

Humidifier

As a rule, such devices are designed to work in rooms up to 150 square meters. The principle of its operation is as follows: water is poured into a special tank to a certain level. During operation of the humidifier, water evaporates and saturates the air with its molecules.

There are three types of humidifiers.

traditional type

The mechanical humidifier fulfills its mission with the built-in fan. It drives air through a special container with water, as a result of which the air is cleaned of dust and saturated with moisture.

Important! A significant disadvantage of such a device is the high noise level during operation and the limited possibility of humidification. A traditional humidifier can raise the humidity of the air only up to 60%.

Steam type

A similar device works in the same way as a kettle. The water boils and comes out as steam. Some models have special nozzles for inhalation. Thus, the device can be used not only to increase air humidity, but also to treat the respiratory tract.

Important! A steam humidifier can increase the air humidity to over 60%.

Flaws:

• Hot steam, the temperature of which reaches 60 degrees, can lead, if safety rules are not followed, to damage human skin and the surface of nearby objects.
• High noise level during operation.
• Fairly high power consumption.

ultrasonic type

Such a device, thanks to the built-in special membrane, turns water into steam. It is less noisy than mechanical and steam humidifiers. The presence of a water heating function contributes to effective fight with microbes in the air.

Works only with distilled water or with special cleaning cartridges to clean and soften the liquid. The latter should be changed regularly.

Important! When choosing a humidifier, be sure to consider the size of the room. Otherwise, its use can lead to excessive moisture.

Folk ways to increase humidity

In the absence of a humidifier, you can use simple folk methods not only to determine the humidity in the room at home, but also to correct the situation.

In this case, the following measures are suitable:

• The easiest way is to place a wet towel or sheet on the radiator. When the fabric is heated, the water from it will begin to evaporate. After drying the towel, it should be wetted again.
• An analogue of the first method is the placement of water containers on heaters. It will be necessary to add water inside the tank every few days.
• You can arrange a container of water on pieces of furniture, such as a closet. With this method, water does not evaporate as quickly as on a battery, but still, the humidity rises.

Important! An aquarium with fish also has a beneficial effect on air humidity, like any other container with water.

• For the next method, you will need a bowl of water and a bandage. Having placed a cup of water near the battery, one end of the bandage should be placed in water, and the other should be fixed on the heating element. Water will constantly rise up the threads of the bandage and evaporate into the air with the help of the heat coming from the battery.
• If the air is too dry, drying your laundry indoors can moisten it.
• Availability a large number indoor plants have a beneficial effect on the normalization of the level of humidity in the air.
• Leave the bathroom door open after showering. Thus, you will get rid of excess moisture in the bathroom and saturate the air of other rooms with it.

How to lower humidity?

If there is a high level of humidity in the rooms, then you should start dehumidifying the air.

Air Dryer

A special device will effectively and quickly remove excess moisture from the air. It drives the air through the “evaporator”, where, due to the temperature difference, moisture turns into condensate. Drops of water flow into a specially designed container. The air warms up again and returns to the room.

Important! When buying such a unit, you should pay attention to its performance, which is measured by the number of liters per day.

A dehumidifier for domestic needs can absorb from 12 to 300 liters of water per day and can be of two types: portable and stationary:

1. The first version of the device can be transferred from one room to another.
2. The second one cannot be moved to another room, since it is mounted on the wall.

Important! Dehumidifiers can be used even in cold rooms. Frost formed during operation is automatically removed. When the water tank is completely filled and untimely emptying of the water tank, the dehumidifier automatically turns off.

Moisture absorber

Such a device is very convenient to use in small rooms. A special tablet, which is included in the device, adsorbs water from the air. It is designed mainly for an area of ​​\u200b\u200bup to 20 square meters.

Important! The main disadvantage of the absorber is the need for frequent tablet changes.

As a rule, such a device is used when high humidity occurs during a certain season.

Important! The absorber is very convenient to use, does not make noise during operation, has compact dimensions and favorable cost.

Folk methods for lowering humidity

In order not to spend money on the purchase of special devices, and if the issue of high humidity is not critical, then you can use one of simple ways available to everyone:

• Regular airing, even in rainy weather, helps to reduce the amount of moisture in the air of the room. The more often airing is carried out, the more the air dries.
• Sunshine through open windows helps dry the room.
• In rooms where ventilation is not possible, such as in a toilet or bathroom, it is necessary to get rid of excess moisture with an exhaust hood. However, they often do not cope with a large load. The installation of an exhaust fan comes to the rescue.

In addition, household appliances that are used for other purposes can also help.

• An oil cooler with a built-in fan is able to rid the air of a small room of excess moisture.
• Modern air conditioners regulate not only the air temperature in the room, but also the level of humidity.

Important! Interestingly, air temperature and humidity are important not only for humans:

• indoor plants also need a certain moisture value - from 40 to 70%;
• household appliances and electronics are well preserved at a humidity of 45-60%;
• antiques, furniture and books - at 40-60% humidity.

Take seriously the problem of overdried or too humid air. If there are problems with this, then it is necessary to solve them quickly, because they can result, at least, in poor health.

MEASUREMENT OF PHYSICAL AND CHEMICAL PROPERTIES OF SUBSTANCES - MOISTURE CONTENT

Measuring the moisture content of substances in the chemical industry is necessary to determine the moisture content in gases, solids or bulk materials.

So, to control the moisture-thermal regime in furnaces, chambers and other technological devices, it is necessary to control the current value of air or gas humidity.

In chemical engineering and other industries, it is possible to single out a drying process based on a change in humidity, which is unthinkable without measuring the current values ​​of the moisture content of products. This is an energy-intensive technological process, which consumes up to 15% of the fuel consumed in the country, for example, removing moisture from mineral fertilizers before packaging in hermetic bags, drying cement and other target products.

1. Measuring the humidity of gases

It is difficult to name an area of ​​human activity where it would not be required to measure the moisture content in gases. The process closest to us is the removal of moisture from the air intended for use in pneumatic automation systems in the petrochemical and chemical industries.

To characterize the humidity in air or gases, i.e., the content of water vapor in them, a number of quantities are used:

Absolute humidity Q is the mass of water vapor contained in a unit volume of gas - wet or dry.

Volumetric moisture content x is the ratio of the volume of water vapor to the volume of gas. This timeless quantity is expressed in relation to the volume of dry or wet gas.

Partial pressureℓ is the elasticity of water vapor. It is expressed in units of pressure, most often in mm Hg.

Dew point temperatureτ is the temperature that a wet gas will take if it is cooled to full saturation with respect to a flat water surface.

Relative Humidityφ is the ratio of the actual gas moisture to the maximum possible gas moisture at a given temperature. Relative humidity is expressed either in relative units - φ ≤ 1 or as a percentage φ ≤ 100%.

φ = ℓ / E or φ = 100*ℓ / E,

where ℓ is the elasticity of water vapor in the air;

E is the elasticity of saturated water vapor at a given temperature.

The main methods for measuring the humidity of gases are the following:

1. Psychrometric method, which is based on measuring the temperature of two thermometers - "dry" and "wet". The difference between them is the basis for determining the humidity of gases.

2. dew points, is to determine the temperature at which the gas is in a state of saturation, i.e., water vapor condenses.

3. Sorption method, is based on the use of hygroscopic bodies that can change depending on the absorbed moisture.

4. Complete absorption, which consists in passing a given volume of gas through a certain substance, while the substance must absorb water vapor and measure its properties. There are two varieties of this method - weight and chemical.

With the weight method, the moisture content is determined by the weight gain of the sorbent that absorbs water. And in the chemical - the moisture contained in the gas under study enters into a chemical reaction. For example, with calcium carbide, some gas is released or the temperature rises.

The above moisture measurement methods are direct or absolute, have high measurement accuracy and are used in laboratory research and as standard instruments for calibrating various means of instrumentation that record the current moisture content of gases.

5. condensation method, which consists in the fact that the gas is cooled in the refrigerator until the moisture is completely condensed, which is then measured, it is also absolute, but requires more time-consuming operations that are unacceptable, for example, when calibrating instruments.

6. thermal method, uses the effect of different thermal conductivity of dry and wet gases.

7. radiation method, is based on the dependence of the degree of absorption of infrared radiation passing through the volume of gas and depending on its humidity.

8. capacitive method, is based on the principles of operation of a capacitor, if there is no moisture between its plates, then the capacitance value is much greater than when there is wet gas in the gas between the capacitor plates.

9. Conductometric method, the dependence of gas humidity on its electrical conductivity is used, with an increase in humidity, the electrical conductivity of gases increases.

The list could go on, but the first three methods are of particular interest to us, and we will look at them in more detail.

Psychometric method

The method is based on measuring the temperature of the medium, the humidity of which must be determined using two thermometers, one of which is used under normal conditions - it is called “dry”, and the other, the so-called “wet”, is wetted by water and is in thermodynamic equilibrium with environment. Evaporation from the “wet” is the more intense, the lower the humidity of the measured gas, and therefore, its temperature will be lower than that of the “dry”. The temperature difference between dry and wet thermometers is used to judge the humidity of air or gas. The semi-imperial formula is used to determine the moisture content:

ℓ \u003d Em-A * P * (tc-tm)

ℓ - elasticity of water vapor in the measured medium;

Em is the maximum possible vapor pressure at temperature tm;

R - Atmosphere pressure;

A - psychometric coefficient

tc and tm are readings of “dry” and “wet” thermometers.

The psychometric coefficient A depends on many factors, including the size and shape of the sensing element, the condition of the wetting wick to protect thermometers from radiation, etc. and is determined by special psychometric tables compiled for certain designs of psychrometers.

Of particular importance, obviously, is the speed of the air. With increasing air velocity, A rapidly decreases, but at speeds of more than 2.5-3 m/s, it practically becomes constant. Therefore, when using industrial psychrometers, it is necessary to provide for a constant flow velocity of at least 3-4 m/s.

The simplest, however, the most common, is a psychrometer, consisting of 2 identical mercury stick thermometers located side by side. The mercury cartridge of one of the thermometers is wrapped in a cloth, the end of which is in a tank of water. Thus, the barrel of this thermometer is always wet, and therefore its temperature is always lower than that of the “dry” thermometer adjacent to it.

Fundamentally, electrical psychrometers do not differ from the simplest ones, except that in the sensors of electrical psychrometers, thermocouples, metal resistance thermometers, or semiconductor thermal resistances (RTs) are used to determine the temperature.

Thermoelectric sensors are made in the form of thermopiles, divided into two groups. One of these groups is wetted by water. The EMF measured at the terminals of the thermopile is proportional to the psychrometric temperature difference.

The schematic diagram of the measuring circuit of the psychrometer is shown in fig. 1 and consists of two bridges having one common point and independent power sources ( U 1 And U 2).

Rice. 1. Schematic diagram of the psychrometer

Bridge I contains a “dry” vehicle as a shoulder - R with, and the bridge II contains “wet” vehicle – R m. In the diagonal of the bridge I included rheochord R p, and to the output of the zero pointer H output voltage difference U m bridge II and stress U p between the beginning of the reochord R p and his engine. With an appropriate selection of constant resistances included in the bridges I And II, you can write:

UM = K1 * (tm - ta)

UP = K2 * (tc - tb)

the disadvantage is that the readings of psychrometers depend on the speed of air or gases.

dew point method

Thus, the rheochord scale can be calibrated as a percentage relative to humidity. A big disadvantage of psychrometers using "dry" and "wet" thermometers is the inability to use them at temperatures below the freezing point of water. In some special occasions liquids with a freezing point below the freezing point of water are used, however, this significantly reduces the accuracy of the measurement. Another significant drawback is the dependence of psychrometer readings on air or gas velocity.

dew point method

The dew point method, previously used exclusively as a laboratory method, with the development of automation has become one of the main methods for controlling the humidity of air and gases, especially at sub-zero temperatures and at any pressure. In this method, the test gas is cooled until saturation occurs, i.e. to the dew point.

Knowing the dew point temperature τ and test gas temperature θ g, it is easy to determine its relative humidity:

where E τ is the elasticity of saturated vapor at temperature τ, and E θ
saturated vapor pressure at temperature θ g

At constant pressure, the dew point does not depend on the temperature of the gas under study. Due to this, it is possible to install the sensor outside the investigated medium at a considerable distance and supply gas to it through a gas pipeline.

The dew point measurement itself is reduced to temperature measurement, the temperature measurement technique is the most well developed, and accurately high enough. To determine the moment of occurrence of the dew point, a metal cooled mirror is usually used, the temperature of which at the moment of condensation on it is fixed as the dew point. In this case, the surface of the mirror must be degreased and cleaned of dust. The dew point is fixed in automatic devices using photocells or by measuring the electrical resistance of the surface layer of the mirror. A diagram of one of the types of devices based on the use of the dew point method is shown in fig. 2.

Rice. 2. Block diagram of the instrument using the dew point method

The mirror is polished surface hollow cylinder through which coolant flows. Her temperature controlled by the heater. A photocell (PV) is illuminated by a light flux reflected from a mirror surface, the constant source of which is an incandescent lamp. The secondary device is most often a device with a falling darling. When fog appears on the mirror, the PV gives a signal, the darling falls and presses the arrow to the indicating scale of the device.

Sorption method

The sorption method for measuring moisture content is based on the ability of some substances with a porous structure to adsorb (absorb) moisture on the pore surface.

Rice. 3

The high magnification view of the pore is shown in Fig. 3. The amount of water adsorbed on the surface of the pore will be the greater, the higher the humidity of the gas, as a result, the properties of the material from which the sensor is made will change. These properties include mechanical, electrical, weight, color, etc. As a rule, changes in the mechanical and electrical properties of sorbents are most often used to assess changes in their moisture content.

The psychrometric method consists in evaluating the characteristics of dry and wet thermometer readings (psychrometric difference) using psychrometric tables. The most widespread are two types of psychrometers: August and Assman.

August psychrometer consists of two thermometers. The dry bulb indicates the temperature of the surrounding air; the thermosensitive element of the second thermometer is wrapped with an hygroscopic cloth, the end of which is lowered into a vessel with water. Due to the evaporation of moisture from the surface of the fabric, the temperature of the latter decreases, reaching in the steady state at a really 100% humidity of the temperature according to the wet thermometer t m. This process meets the condition i = const, since for air the amount of heat introduced with evaporated moisture is exactly equal to the costs heat for its evaporation. The evaporation surface temperature will depend on relative humidity air φ: the lower the value of φ, the more intense the process of evaporation of moisture and the lower the value of t m will be. The difference between the readings of dry (t c) and wet (t m) thermometers is called psychrometric difference. At t m \u003d t c, the relative humidity of the air is 100%. Knowing the psychrometric difference and air temperature, you can use the i-d diagram or attached to the device psychrometric tables determine φ.

Assmann psychrometer belongs to the aspiration type due to the creation artificial ventilation thermometers for guaranteed fulfillment of the condition of equality of the temperatures of the sensors to the values ​​of t m and t c . Screening of mercury capsules with metal tubes and blowing air through them using a special fan with imported or electric drive increase the accuracy of measurements (external thermal radiation to the device is eliminated and the heat exchange of air with the sensitive elements of thermometers is improved). Relative humidity φ is determined with an accuracy of 1 ... 2%.

Hygrometric method

The hygrometric method is based on the effect of changing the length of a thread made of one or another hygroscopic material (fat-free hair, nylon thread, etc.) when the ambient humidity changes. Devices that implement this method are called hygrometers. The drier the air, the shorter the sensitive element of the device becomes (a thread connected by a system of levers with an arrow indicating the current value of relative humidity φ on a graduated scale). Hair hygrometers such as MV-1 and MVK, film hygrometers M-39, etc., became widespread.

Psychrometric and hygrometric are practical methods for determining air humidity. There are also two more methods for determining air humidity - this is a remote measurement and a mass method, we will consider them in more detail.

Remote measurement

Remote measurement of relative air humidity allows you to control it without depressurization of the cargo chamber. For this, a remote hygrometer is used, which consists of: a hygroscopic thread, an induction coil, a magnetic core and a measuring device.

To automatically record the relative humidity of the air for a given period of time, a device called hygrograph. Instead of an arrow, a pen is placed in it, on which ink is continuously supplied. Registration is carried out using paper on a drum with an hourly or daily winding. Thus, a continuous curved line of passable values ​​of φ is drawn. Other devices also implement the principle of measuring the electrical resistance of a thread during fluctuations in air humidity.

Bulk method

This method is based on the precise measurement of the moisture content in the air. The investigated air, the volume of which is controlled by a special counter, is driven through tubes filled with a moisture absorber (silica gel, calcium chloride, etc.). The difference between the masses of the tubes with the adsorbent before and after passing air shows the amount of absorbed moisture. By dividing the mass of moisture by the volume of air passed, the density ρ p is obtained, that is, the absolute humidity of the air. Knowing the temperature t c , according to the table of saturated air, its density in the saturation state ρ p. n and relative humidity are determined: φ = ρ p / ρ p.

Humidity control in the cargo area of ​​a refrigerated car is carried out in an integrated way - by introducing restrictions on the ventilation mode with outside air

Control and organization of regulation of air humidity in railway transport

The regulation of air humidity is carried out only in passenger cars by using humidifiers - devices with nozzles for spraying water. Such devices are switched on from sensors located in the cars. Humidity management in the cargo area of ​​a refrigerated car is carried out by organizational methods - by introducing restrictions on the route and the appropriate technology for unloading LNG (perishable goods).

The humidity regime during LNG transportation in insulated wagons is not controlled and regulated, and therefore is not standardized by the rules. This is due to the lack of reliable devices for remote control of relative air humidity and technical means of influencing it in the cargo spaces of cars on isothermal rolling stock.