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Air humidity, significantly affecting the heat exchange of the body with the environment, is of great importance for human life.
People usually feel better in humid air. Optimal for us is the relative humidity of 45 to 55% at a temperature of 18 - 24°C. Do you know what is common between the Sahara desert and an ordinary apartment with central heating? Air humidity! Only 20-25%!
A person develops a sore throat, dry skin, runny nose and general fatigue. But it's not just about comfort. Dry air is also a direct threat to health: the body is acutely lacking oxygen, and hence fatigue, inability to concentrate, and increased stress on the heart.
Skin ages faster. Microbes easily settle on the overdried mucous membranes of the nose and throat, which means that you catch a cold more often. Not only our health depends on the air, but also the psychological mood. In some rooms we do not feel very well, although we cannot understand the reasons for this.
At the same time, an average person spends more than 20 hours a day indoors. Humans are highly susceptible to humidity. It depends on the intensity of evaporation of moisture from the surface of the skin.
At high humidity, especially on a hot day, the evaporation of moisture from the surface of the skin decreases and therefore thermoregulation becomes more difficult human body.
In dry air, on the contrary, there is a rapid evaporation of moisture from the surface of the skin, which leads to the drying of the mucous membranes. respiratory tract.
In air with high relative humidity, evaporation slows down and cooling is negligible. Heat is more difficult to tolerate with high humidity. Under these conditions, it is difficult to remove heat due to the evaporation of moisture.
Therefore, overheating of the body is possible, which disrupts the vital activity of the body. For optimal heat transfer of the human body at a temperature of 20-25 ° C, the most favorable relative humidity is about 50%.
Thus, the following conclusion can be drawn:
- At low temperatures and high humidity, heat transfer increases and a person is exposed to greater cooling.
- At high temperatures and high humidity, heat transfer is sharply reduced, which leads to overheating of the body. High temperatures are easier to bear when the humidity is lower.
- Most favorable for a person in the middle climatic conditions is the relative humidity of 40-60%.
- Ventilation, air conditioning, etc. are used to eliminate the adverse effects of indoor air humidity.
- that everyone wants to look attractive, for a long time stay young and beautiful. Our hair, in dry air, evaporating moisture, becomes thinner and cracked, split at the ends and easily broken off when combed. Hairstyle in this case looks terrible.
Heating appliances operating in winter period, dry the air and cause evaporation of moisture from the skin. Dry air, like a sponge, seeks and absorbs moisture wherever it is found. Our skin is no exception.
To completely avoid dry skin in winter, it is enough not to expose it to the dry air that occurs during the operation of heating devices. To do this, the relative humidity in the room must be at least 50%. In winter, it usually does not exceed 20%. To maintain the desired level of humidity, you can hang wet towels or put a bath of hot water on the radiator.
- Our body consists of two-thirds of water, so the relative humidity of the air affects health and well-being. The lower the humidity, the faster the evaporation during breathing, which helps to cool the body. The consequence of dry air is the body's susceptibility to colds.
Colds and runny nose are spread by airborne droplets or through bodily contact with the sick. Main function skin - to be a barrier to bacteria. If the skin and mucous membranes of the nasopharynx are dry (and they lose moisture under the influence of dry air), then the barrier becomes less effective.
Dry air leads to a weakening of the immune system as a whole, exacerbates skin allergies. In addition, it causes dust to fly around the room, and its particles enter the respiratory system, which can lead to lung diseases.
In order to bind fine dust particles, you need to either perform daily wet cleaning or install a humidifier in the room. The humidifier helps bind fine dust particles and prevents the spread of harmful bacteria.
Insufficient humidity in the room may indicate appearance indoor plants. In dry air, plants begin to evaporate more water through the stomata on the leaves, and their water balance is disturbed:
- The leaves are wrinkled or curled.
- The tips of the leaves turn brown and dry up. This can often be observed, for example, in ficus Benjamin, nephrolepis, and also cyperus.
- Young leaves are not fully developed.
- The buds do not open or fall off.
- Some pests especially often infect plants if the air is too dry. These include, first of all, spider mites, thrips and whiteflies.
There are several ways to increase the humidity in a room.
One of the ways to increase the humidity in the room is spraying. With this simple and effective method, you can increase the humidity in the immediate vicinity of the plant. It is best to spray the plant in the morning so that the leaves dry out during the day.
Humidifiers are used to increase humidity: an ultrasonic humidifier, a cold fan humidifier (drives air through a wet filter), steam humidifiers are similar in principle to electric kettles. Plants can help themselves very well if they are grouped so that plants that evaporate a lot of moisture are next to those that prefer high humidity.
High humidity also at any temperature is bad for human health. It can occur due to large indoor plants or not regular ventilation. At higher temperatures, a humidity of about 20% is preferred.
In weaving, confectionery and other industries, a certain humidity is necessary for the normal course of the process (see table 1).
Table 1. Several processes and industries that require air humidity control
The storage of works of art and books requires maintaining the humidity at the required level. Therefore, in museums, you can see psychrometers on the walls.
On any food product indicate the value of relative humidity acceptable for storage.
The optimal and permissible parameters of temperature and relative humidity in the premises of educational and preschool institutions are presented in Table 2.
table 2
Note : air speed - no more than 0.1 m / s.
Great importance has knowledge of humidity in meteorology for weather forecasting.
01.10.2015How much do we know about the impact of humidity on human health? Probably, most of us will immediately be able to remember how bad it feels in the heat, if the humidity is high outside. And someone more knowledgeable will say that low air humidity is also bad: especially if you catch a cold and start coughing. So where is the golden mean that you need to know about in order to avoid negative impact humid air to your health? Let's try to figure it out together.
Influence of low humidity
We all know that a person is almost 90% water. Too dry air always causes peeling of the skin, dries the mucous membranes, due to which they become covered with microcracks. All this leads to infectious and inflammatory processes. It is also important that low humidity adversely affects the heat exchange in the body. If the level of air humidity drops to 10%, then even perfectly healthy people will have a feeling of dryness in the nasopharynx, the eyes will start to hurt and redden due to overdrying, and some may even start nosebleeds.
For people who suffer from respiratory diseases (bronchial asthma, bronchitis, etc.), due to the low level of humidity, well-being can deteriorate greatly, attacks will become more frequent. And if you have bronchitis, it is because of the dry air that it can develop into pneumonia. Agree, not a very bright prospect.
As for the positive impact of humidity on human health, it is the low level of moisture in the air that makes people feel more comfortable at very high temperatures. And severe frosts at low humidity are much more comfortable than at high humidity.
Influence of high humidity
People suffering from hypertension, cardiovascular diseases, and atherosclerosis know better than anyone about this side of the issue. When the humidity rises to 80% and above, they usually get sicker.
If we talk about absolutely healthy people, then at high humidity and an air temperature of + 25 ° C, their heat transfer from the skin is disturbed, as a result of which the body can overheat. This is manifested by a feeling of stuffiness, heavy breathing, deterioration in well-being, and a decrease in working capacity. It has been proven that a person who is constantly in rooms with very high humidity is highly susceptible to the development of infectious and colds, kidney diseases, rheumatism and tuberculosis. In addition, in rooms with high humidity, mold and fungus actively develop, which infect the air we breathe.
Optimal Humidity
To reduce the negative impact of humidity on human health, it is necessary to follow sanitary recommendations on the optimal level of air humidity. It is recommended to keep it at the level of 40-70%. This is an extremely important microclimate criterion. FROM special attention you need to refer to this indicator if there are children in the house. A newborn baby especially needs to have moist air around, otherwise his skin will dry out. In addition, moist air makes breathing easier for the baby and prevents the mucus in the nose from drying out. Dry air for a baby is dysbacteriosis, impaired kidney function, the appearance of allergic reactions, and the development of chronic diseases.
Often the concept of "humidity" is associated with phenomena that have a negative connotation.
In fact, many of our ideas about humidity are erroneous and based on superficial knowledge of what it really is.
The purpose of this article is to look at the most common "false myths" about humidity, to understand that it is more important (and even more valuable) than we think.
In fact, there is often a need to create and maintain this air parameter with the help of humidifiers.
It's foggy outside
One cubic meter of outdoor air at 0°C and 75% relative humidity contains 2.9 grams of water vapor; the same air heated to 20°C ( average temperature in the house) without the addition of water vapor has a relative humidity of 20%, which is too low to feel good! In fact, the minimum relative humidity required for human comfort and health is about 45%-50%.
Relative humidity depends on temperature: the hotter the air, the lower the relative humidity.
For example, winter outside air at 0°C on a foggy day(100% relative humidity), heated indoors to 22°C, gives a relative humidity of 23%. In places with very dry winters, say, with an outside temperature of 0°C and a relative humidity of up to 30%, when the air is heated to 22°C, the relative humidity drops to 7%.
As a result, even if it is foggy outside (a lot of moisture in the air), this is not a guarantee that the humidity level inside the heated room will be correct.
To achieve the optimum humidity value, the air must be humidified.
Humidity and feeling cold
There is also a physiological effect of humidity that is often overlooked: the effect on the perception of heat or cold. We all know that sweating is an important part of the body's thermoregulation process: the evaporation of sweat removes heat, thereby cooling us.
In summer, when it is hot, increased sweating keeps our skin at a comfortable temperature. High humidity prevents evaporation (stuffiness), while dry air favors this process.
In winter, dry air promotes evaporation and thus cools the skin. The immediate effect of this phenomenon is that at the same temperature, the drier the air, the colder it seems to us.
Under typical heated room conditions "apparent temperature"(i.e. subjective perception of temperature related to personal comfort) increases by about 2 °C if the relative humidity rises from 25% to 50%. In other words, if the humidity is at the right level, in addition to all the other benefits, we can save on heating costs.
The effect of dry air on people and objects
Humidity is also very important for human health.
One of the problems caused by low humidity is the feeling of eye irritation., that is, dryness of the cornea, which is often a serious problem for people who wear contact lenses. The amount of moisture in the air affects our skin,hands and face dry and chapped at low humidity in the first place, as they are in direct contact with dry air.
Another problem is the dryness of the mucosa in the respiratory tract, which can exacerbate asthma and allergy sufferers, and generally reduces the body's defenses.
Examples of the negative impact of low humidity on objects and things can be given endlessly. “Hygroscopicity” is a term characteristic of materials whose particles absorb moisture, which leads to a change in their size. Such materials include paper, fabrics, some types of plastic, wood, fruits, vegetables and other materials that tend to absorb or release moisture.
Besides, humidity affects physical characteristics materials, such as toughness (eg photoresist in microelectronics), mechanical strength/brittleness (textile, tobacco, woodworking) and electrostatic discharge potential (paper, textiles and electronics).
Sources of humidity in our home
We have many sources of moisture in our home, from clothes hung out to dry to boiling water used to make pasta.
Moreover, people enter and leave the house, windows open, walls exude moisture, not to mention the appearance of small cracks and holes. One little known fact is that a small amount of fresh air entering the house when a window is opened has little effect on the room temperature, but causes a strong decrease in relative humidity.
In other words , water vapor "escapes" much faster than heat, due to physical properties gases.
The paradox is that airing the room in winter without additional humidification reduces the quality of the air, making it too dry.
Besides, water containers placed indoors or attached to radiators are useless, because too little water evaporates.
To check this, measure the humidity with a simple wall hygrometer, with and without an additional container of water - the difference will be negligible.
Humidity- the main parameter of the environment, along with temperature and air velocity, which affects the evaporation of water from a wet or wet surface. The effect of humidity on the human body is especially noticeable when breathing: passing through the upper respiratory tract into the bronchi, the air heats up upon contact with the walls of the vessels of the respiratory tract . These walls are connected with the mucous membrane, which is covered with moisture under normal conditions.
Passing through the respiratory tract into the bronchi, the air is heated and humidified, almost reaching a state of saturation. The exhaled air becomes warm and humid, this is evidenced by the condensation of water vapor when breathing in a cold room or deposition in the form of droplets on cold surfaces.
The mucous membrane of the airways filters the air, freeing it from various impurities, bacteria, viruses. The inner surface of the bronchi is covered with ciliated epithelium, which captures foreign particles. These particles are excreted from the body with the help of secretions, which are removed only if their viscosity in relation to water is not too high. If the humidity is low, then the evaporation of water from the mucous membrane will be too intense, which will lead to its drying. The filtering ability of the ciliated epithelium in the bronchi also decreases and the dirt contained in the air easily enters the respiratory tract. A feeling of dryness of the mucous membrane signals the presence of bacteria or viruses that affect the mucous membrane of the nasal cavity, spreading through the bronchi and reaching the lungs.
The amount of moisture that evaporates depends only on the humidity of the inhaled air, since the exhaled air is at body temperature and is saturated. It is also clear that, at the same moisture content, higher temperature air will cause more mucosal dehydration than lower temperature air.
Let's give an example: when inhaling air with a moisture content of 3 g / kg. dry air In winter conditions, the feeling of dryness will be less than when inhaling air with the same moisture content (relative humidity 20%) at a temperature of 20-25 C. Since the air temperature in the lung cavity is 34 C, its moisture content under saturation conditions will be 34 g / kg. dry air .. The amount of water evaporated from the mucous membrane for each kg of air inhaled:
G exp = xlu— xamb=34,6-3=31,6 G kg dry air.
With weak physical activity, a person inhales about 1 m 3 / h of air or 1.2 kg / h, thus losing about 35 g of water every hour.
In cold conditions, this is imperceptible, which cannot be said about staying in conditions of high temperature.
Dryness of the mucous membrane of the upper respiratory tract limits its filtering capacity, promotes the penetration of impurities into the body and, at the same time, increases the amount of water evaporating from the bronchi. An increase in the viscosity of the mucus limits or inhibits the mobility of the ciliated epithelium, lowering the infection barrier.
Drainage of the respiratory tract leads to intense vasodilation and profuse sweating. To avoid these phenomena, warm air must be sufficiently humidified. Studies have shown that the minimum allowable relative humidity is approximately 30%, the maximum allowable humidity is approximately 80-90%.
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INTRODUCTION
Human health directly depends on the quality and condition of the air that he breathes. After all, it affects the vital activity, performance and well-being of the human body. A survey I conducted among school students showed that the main characteristic of the air that respondents are interested in is cleanliness and few people think about the humidity of the air we breathe. But not only the state of human life depends on this factor, but also animals, plants, as well as the safety of technical objects, architectural structures, works of art. Of great importance is the knowledge of humidity in meteorology for weather forecasting. Food, building materials, books and even electronic components can be stored within a strictly defined range of relative humidity. Many technological processes are possible only with strict control of the content of water vapor in the air of the production room.
In my work, I propose to consider in detail, learn how to measure and regulate such an important air characteristic as humidity.
Target: The study of the influence of air humidity on human life.
Tasks:
To get acquainted with the concept of air humidity, find out on what parameters it depends, how it is calculated.
Discuss the principle of operation of devices that measure air humidity.
master different ways measurement of air humidity.
To study the influence of air humidity on human life.
Measure the air humidity in different rooms of the school and compare the obtained data with sanitary and hygienic standards.
Suggest options for normalizing air humidity.
Object of study: percentage of moisture content in the premises of the school.
Subject of study: influence of air humidity on human activity.
Research methods:
Questioning.
Working with literature and materials in the media.
Experiment.
Comparison and analysis.
Hypothesis: if you find out on what parameters air humidity depends and learn how to regulate it, you can create a favorable microclimate for human life.
Practical significance: formulated ways to regulate air humidity.
THEORETICAL BASIS
1.1. Physical calculations and air humidity parameters
Atmospheric air consists of nitrogen, oxygen, carbon dioxide and some other gases, which make up no more than 1% of the total mass. But besides these gases, the air also contains water vapor and other impurities. Water vapor in the air is usually unsaturated. Saturated vapor is in dynamic equilibrium with its liquid. This state is characterized by the fact that the number of molecules leaving the surface of the liquid is equal, on average, to the number of vapor molecules returning to the liquid in the same time. The name of the steam - saturated - emphasizes that at a given temperature, a greater amount of steam cannot be in a given volume. If the vapor has not yet reached a state of dynamic equilibrium with the liquid, it is called unsaturated. The movement of air masses, ultimately due to the radiation of the Sun, leads to the fact that in some places on our planet in this moment evaporation of water prevails over condensation, while in others, on the contrary, condensation prevails.
Under the humidity of the air is understood the amount of water vapor, which at the moment (and in this place) is contained in air mass. To characterize the content of water vapor in the air, a number of quantities are introduced: absolute humidity, partial pressure and relative humidity.
Because, atmospheric air is a mixture of various gases and water vapor, then each of the gases contributes to the total pressure produced by air on the bodies in it. The pressure that water vapor would produce if all other gases were absent is called the partial pressure (or elasticity) of water vapor. The partial pressure of water vapor is taken as one of the indicators of air humidity. It is expressed in units of pressure - pascals or millimeters of mercury.
Absolute humidity (water vapor density) indicates how many grams of water vapor are actually contained in one cubic meter of a particular air mass. . O bo-knowingab-so-fierce humidity: (as well as the usual-but-ven-noe designation of density). Unitsab-so-fierce humidity: (in SI) or (for convenience, due to a small amount of water vapor content in the air). Formula you-number-le-nia ab-so-lut-moisture-no-sti:
Designation:
mass of steam (water) in air, kg (in SI) or g;
the volume of air-du-ha, in some rum the indicated mass of steam is contained,.
But this ve-li-chi-na is inconvenient from the point of view of vos-pri-im-chi-in-sti-moisture of life-you-mi-or-ga-niz-ma-mi. Oka-zy-va-et-sya, for example, a person feels not the mass content of water in the air, but the name but its content is from-no-si-tel-but mak-si-mal-but possible-no-th meaning.
To describe such a perception of such a perception, enter-de-na such a ve-li-chi-on as from-no-si-tel-naya humidity. From-no-si-tel-naya humidity of the air-du-ha - ve-li-chi-na, in-ka-zy-va-yu-shcha, how far the steam is from the sy- schen-tion. That is, ve-li-chi-on from-but-si-tel-noy humidity, in-ka-zy-va-et the following: if the steam is far from na-sy -shche-tion, then the humidity is low, if close - you are with-kaya.
Designation-che-neot-no-si-tel-noy humidity:. Units of me-re-niyaot-no-si-tel-noy humidity:%. For-mu-la you-number-le-niya from-no-si-tel-noy humidity:
Designation: density of water vapor (absolute humidity), (in SI) or, partial pressure, Pa (SI) or mm Hg. Art. - density of saturated water vapor at a given temperature, (in SI) or, saturation vapor pressure at a given temperature, Pa ( SI) or mm Hg.
Thus relative humidity air is called the ratio of absolute humidity expressed as a percentage to the density of saturated vapor at a given temperature (or the ratio of the partial pressure of water vapor to the pressure of saturated vapor at a given temperature).
The lower the relative humidity, the further the steam from saturation, the more intense the evaporation. Saturated vapor pressure at a given temperature is a tabular value. The partial pressure of water vapor (and hence the absolute humidity) is determined by the dew point. The dew point is the temperature at which water vapor becomes saturated.. When cooled below the dew point, vapor condensation begins: fog appears, dew falls, windows fog up. The dew point allows you to determine the elasticity of water vapor in the air at a certain temperature, and hence the partial pressure of water vapor and absolute humidity using tables that show the dependence of pressure and density of saturated water vapor on temperature.
The pressure of saturated water vapor at an air temperature equal to the dew point is the partial pressure of water vapor contained in the atmosphere.
1.2. Instruments for measuring air humidity
The problem of air humidity has been of interest to people since ancient times, especially where the climate is dry and hot. To solve it, the most common methods were used: cloth or paper soaked in water, dishes with liquid .. A modern device for measuring humidity is a hygrometer.
Currently, there are several versions of the hygrometer.
-
ceramic;
condensation;
electronic;
psychrometric (psychrometer)
hairline;
In fact, the principle of operation of any hygrometer is quite simple and is based on physical or chemical properties materials and substances.
Almost any hygrometer is suitable for domestic use, but electronic hygrometers still provide the most accurate data.
1.3. The influence of air humidity on human life
When the optimal humidity parameters change, immunity decreases. Human health is deteriorating, there is a feeling of fatigue and lethargy. At home, where the climate is changed, the natural balance of humidity is disturbed. This is especially felt in winter. It is at this time that the difference in humidity is the most significant. The air entering the room is dried due to the general heating in the rooms.
Air that is too dry can dry out the skin and dehydrate the body more quickly. First of all, mucous membranes that come into contact with open air suffer, they become covered with microcracks and dry out, opening a direct path to the body for harmful bacteria and viruses. At a relative humidity of less than 10%, even healthy people experience a feeling of dryness in the nasopharynx, “stinging” in the eyes, nosebleeds may even begin. Dry air is especially dangerous for patients with bronchial asthma, they have a general deterioration in well-being, attacks are possible. A sufficiently long stay in dry air threatens with a decrease in immunity and frequent respiratory diseases. This happens due to the fact that the overdried mucous membrane prevents normal breathing, as a result of which the body does not receive enough oxygen.
However, dry air makes it easier to endure low and high temperatures. So, for example, with low relative humidity, summer heat is more easily tolerated than the same temperature, but in areas with high humidity. The same is true for negative temperatures. Very coldy at low humidity they bring much less discomfort than a small "minus" in humid air.
A large concentration of moisture does not allow the human body to maintain a normal temperature - the thermoregulation mechanism does not work properly. The human body uses sweat to cool itself. Sweat, evaporating from the surface of the skin, removes excess heat. With high humidity, the body begins to work with increased strength, and this leads to the opposite result - overheating. Lethargy, vomiting, loss of consciousness, strong blood viscosity and, as a result, heart problems are possible. It is even possible oxygen starvation of the brain.
Patients with hypertension, atherosclerosis, people with various cardiovascular diseases especially react strongly to high humidity. With very humid air (80 ... 95%), exacerbations and attacks are possible.
High humidity combined with low temperature is dangerous for too much hypothermia and frostbite. This can also happen around 0°C, and not only at minus.
Heat saturated with moisture is ideal conditions for the development of bacteria and all kinds of fungi, which can lead to the occurrence and intensification of allergic reactions.
The constant stay of a person in rooms with high humidity leads to a decrease in the body's resistance to infectious and colds, as well as to more serious consequences: kidney disease, tuberculosis, rheumatism, etc.
Not only the human body suffers from high humidity, but also the interior of the premises. In damp places, fungus and mold develop, releasing large amounts of spores into the indoor atmosphere, contaminating the air we breathe. The danger of high humidity is in the slow rate of reactions. For many years, you can not notice the reasons for the deterioration of health, well-being and the appearance of various diseases.
However, saturated moist air is very useful. That is why a person feels good on the shore of a lake or river. Such air saturates the human body, relieving headaches and other ailments. It is no coincidence that during the holidays many people are drawn to the sea coasts.
“Correct” humidity is one of the most important microclimate criteria for a child, especially a newborn. Despite the powerful protective functions just born child, it still has especially vulnerabilities. And first of all, it is the skin, which until the moment of birth was always surrounded by amniotic fluid, and, especially, the mucous membranes.
Humid air in an infant's bedroom makes breathing easier, prevents nasal congestion, and is effective in treating bronchitis, dry coughs, croup, and other respiratory ailments.
Low humidity for adult healthy body- in most cases, this is just discomfort, for a newborn baby - a disaster that provokes dysbacteriosis, kidney problems, and the appearance of allergic reactions. Dry air for a baby is dangerous not only with temporary complications, but with their relapses, which can lead to chronic diseases.
1.4. What determines the humidity of the air
First of all, humidity depends on geographical location and climate. So, for example, near the seas and oceans, the average relative humidity is 70-80%, in the depths of the continents it decreases (in deserts - only 4-5%). A rainy climate contributes to maintaining high humidity in a geographic region, while a dry climate does the opposite.
But no less important is the technogenic factor. Humidity is usually low in big cities. However, inside the premises, it can vary significantly, based on the specifics of their purpose (laundry, kitchen, swimming pool, etc.), as well as on the type of building and finishing materials used.
It is especially necessary to monitor the condition of the air in residential and working premises in winter, when the cold atmosphere cannot retain enough moisture, and the one that is available is trying to dry out the heating radiators.
An important factor is also the presence of ventilation in an apartment, house or any other room. The more intense the air exchange, the faster the air dries out (especially in the cold season). Air conditioners that do not provide the function of maintaining humidity also intensively utilize moisture.
1.5. Instruments and devices with which you can
regulate air humidity
The dehumidifier pushes moist air through the "evaporator" where the temperature difference (the temperature in the appliance is lower than in the room) turns the moisture into condensate. Drops of condensate flow into a special container. The air is heated again and enters the room. Thus, excess moisture disappears from the room. When buying a dehumidifier, the main focus is on its performance, which is calculated in "liters per day". A household dehumidifier can absorb 12 to 300 liters of water in 24 hours. Dehumidifiers are portable and stationary. Portable can be used in different rooms. Stationary mounted in the wall and can not be moved. However, they are more efficient. The advantage of dehumidifiers is their ability to function in cold rooms, since the frost formed during operation is removed automatically. When filling the water tank and untimely emptying it, the device turns off without the participation of the owner. AT small room Moisture can be reduced by using moisture absorbers. The device includes a special tablet that adsorbs water from the air. It is designed for an area of up to 20 m² on average. The inconvenience of the absorber is that the tablet needs to be changed frequently. The advantage is in the absence of noise, compactness and price. Especially the moisture absorber is suitable for those who have humidity - a seasonal phenomenon.
Humidifiers are designed to operate in one enclosed space, such as a room. They do not require special installation: all you need to do is pour water into the tank and plug the humidifier into the outlet. To select a humidifier, you need to know three main components: the volume of the room (the area multiplied by the height of the ceilings), the quality of the water (the water that you will pour into the humidifier), the conditions in which the humidifier will be operated (bedroom, office, children's room, etc.). etc.).
PRACTICAL RESEARCH
2.1. Determination of air humidity in school premises
Since students have to spend more time at school during the school year, the state of humidity in classrooms plays an important role. Based on this, I found out whether the conditions of our offices meet the sanitary standards. The measurements were carried out with an electronic hygrometer in subject rooms, in a computer class, in a canteen and in a sports hall. Measurements and readings are listed in tables.
|
Moisture point |
Air temperature |
Norm, according to SanPin |
Relative Humidity |
Norm, according to SanPin |
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Physics cabinet |
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Biology class |
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Library |
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Canteen |
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Gym |
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medical office |
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2.2 Making a psychrometric hygrometer (psychrometer)
To create an analogue of a psychrometric device, you will need: two alcohol thermometers designed to measure air temperature, distilled water, thread, cotton wool.
Set up two thermometers in a vertical position so that they are parallel to each other. Wrap the tip of one thermometer with cotton wool soaked in water, then tie it loosely with a thread. The principle of operation of such a device, assembled by oneself, is absolutely similar to the principle of operation of a psychrometric hygrometer. To calculate the relative humidity of the air, you need a special table. The difference between the dry and wet thermometer readings is used to calculate the ambient humidity.
2.3 Measurement of air humidity with improvised means
Equipment: a transparent glass beaker 200 ml, a vessel with water (temperature from 0 to 5 ° C), a vessel with hot water, a thermometer, a table of dependence of saturated water vapor pressure on temperature ..
Progress of work: Pour ice water into a transparent glass and lower the thermometer into it. After a while, the outer walls of the cup will fog up. Very slowly add hot water from the second cup until the dew on the walls disappears. Notice the temperature at which the dew has disappeared. According to the table, we determine the partial pressure of water vapor p in the classroom, then, by measuring the room temperature, we determine the maximum pressure of water vapor R 0 in class. According to the formula =(p/p 0) 100% find the relative humidity in the classroom. t \u003d 25 C, p 0 \u003d 3.17 kPa, t \u003d 15 C, p \u003d 1.71 kPa, \u003d 53%.
CONCLUSIONS
Dry thermometer readings - 25 ° С, wet - 17 ° С, difference in readings - 8 ° С, relative humidity - 44%, i.e. 1% higher than indicated by the electronic hygrometer, i.e. this self-made hygrometer gives quite accurate readings and can be used to measure humidity.
Air humidity can be measured by improvised means, for this you need the simplest equipment and a table showing the dependence of pressure and density of saturated water vapor on temperature. But this method turned out to be less accurate.
In all school premises, air humidity is within the norm, but is within the lower limit. By the end of the shift (6-7 lessons), the humidity in the classrooms rises. In offices with a lot of green spaces, the air humidity is much higher.
CONCLUSION
Water is essential element to ensure normal life. It enters the human body mainly with food or drink. However, a sufficient amount of moisture is necessary not only for internal organs, but also for the mucous membranes of the eyes, respiratory tract, and skin. Therefore, it is important not only to take the liquid inward, but also to obtain it from the surrounding moist air. For the normal well-being of people in the room, it is necessary that the optimal humidity of the air is approximately 40 to 60%.
In order to reduce the humidity in the room, you need:
1. Provide good ventilation in the room. Several times a day, it is necessary to ventilate the room where the humidity level exceeds the standard values. Arrange short drafts, but at the same time, the ventilation intensity should be high.
2. Repair all taps and other plumbing. Leaking faucets, radiators, and other structures add moisture to the air, so replace obsolete parts or repair leaking areas.
3. Reduce the number of indoor houseplants. Flowers and miniature trees increase the area of evaporation of moisture in the room - water evaporates from the leaves and moist soil. Give preference to plants that are drought tolerant and reduce the total number of houseplants. 4. Organize a good space heating system. Heating in the cold season should work constantly - periodic shutdowns (for example, at night) increase the humidity of the air and contribute to the formation of dampness on the walls and ceiling.
5. Check the exhaust equipment of the room. The need to install the hood is dictated by the norms of the level of humidity - if the source of moisture is a stove with constant evaporation or a shower, then the construction of exhaust structures is simply necessary. The hood must ensure the removal of exhaust steam and regulate the level of humidity.
6. Choose the "right" finish for the walls. Considering different options for finishing walls, ceilings and floors, give preference to natural finishing materials that absorb excess moisture (drywall, wood).
7. Finish wet cleaning with dry wiping. Mopping, dusting and other chores using water should be completed with mandatory drying - walk over the surfaces with a piece of dry cloth with good absorbent properties.
8. Purchase a special device - an air dryer.
You can increase the humidity in the following ways:
1. Regularly ventilate the room, especially in wet weather, and carry out wet cleaning.
2. Houseplants moisturizing the air, distributed throughout the apartment, will reduce the problem to nothing. For example, cyperus is able to evaporate up to 3 liters per day. Yes, and the process of regular spraying of plants will also significantly help.
3. Deliver large aquarium, you can not even start the fish, but simply decorate the aquarium with decorative stones and algae.4. Arrange water reservoirs around the room, between sections of radiators or under them. It can be jugs or vases with water. You can hang wet towels or sheets on the batteries.
5. Indoor fountains not only moisturize the air well, but also decorate the interior of the room.
6. Use a special device - a humidifier. This device constantly evaporates a large amount of moisture into the air and is able to maintain optimal humidity in the room. You can buy such a device in almost any hardware store.
Practical use of the results.
Humidity is an important characteristic of the air, which has a significant impact on the quality of human life, so it is necessary to monitor the humidity in the room. The device for measuring humidity can be made independently (given detailed instructions), methods for determining humidity are quite simple and affordable. During research work held comparative analysis humidity control devices. Detailed recommendations are given to control the humidity in the room. A study of the premises at the school showed that the humidity standards correspond to the SanPin standards, but are within the lower limit of the norm, which can be explained by the time of the study (heating season). this work can be used in physics lessons or extracurricular activities, as well as for self-education of students.
BIBLIOGRAPHY
1. Purysheva N.S., Vazheevskaya N.E. Physics 10. M.: Bustard, 2013.
2. V.A. Burov. Workshop on physics. M.: Enlightenment, 1973.
3. G.S. Landsberg. Elementary textbook on physics. Moscow: Nauka, 1985.
4. Katz Ts.B. Biophysics at physics lessons. M.: Education, 2004.
5. Ryzhenkov A.P. Physics. Human. Environment. M.: Education, 2006.
6. Perelman Ya.I. Entertaining physics. M.: Nauka, 2008.
7. Methodical newspaper. Physics. No. 18. M.: First of September, 2009.
8. Scientific and methodical journal. Physics at school. M.: School press, 2007. 9. Free electronic library of technical literature.
http://www.allbeton.ru/
http://uchilok.net/
11. Journal "Health and sport". http://getmedic.ru/
12. Site of the company "Inrost".
http://www.inrost.ru/humidifiers/guide/optimal/html
13. The site of the company "Legin climate".
http://www.legion-klimat.ru/
14. Site "Knower".
http://uznay-kak.ru/
15. Economy.ru website. http://echome.ru/
Attachment 1
For the first time, Cardinal N. Cuzansky tried to determine the level of humidity in the middle of the 15th century. He used a scale with wool on one side and stones on the other. At high humidity wool pulled them, saturated with moisture, and the arrow showed this. With increased dryness, stones were pulled.
A doctor from Venice, two hundred years later, built another hygrometer - a string one. Tensioned threads, used as a moisture meter, made a different sound when it fluctuated.
And the Duke of Tuscany made a device in the form of a vessel. The conical vessel was filled with ice, moisture condensed on the outside of the glass and flowed into the measuring glass (the vessel was turned upside down). Everything would be fine, but where to get ice in the summer?
Amonton Guillaume, a mechanic from France, made a hygrometer from a leather ball. The volume of the ball changed, in the tube connected to it, the level of the liquid column changed.
In the 18th century, the Swiss B. Saussure took up the manufacture of a hygrometer seriously and for a long time. After trying many materials, he settled on hair. Boiling them in a soda solution, Saussure made a hygrometer. Created a centigrade scale, The length of the hair changed with changes in air humidity.
This phenomenon was studied in 1895 by B. I. Sreznevsky, a meteorologist, and deduced the dependence of hair elongation on the percentage of humidity. The elongation turned out to be directly proportional to the logarithm of the relative humidity.
Annex 2
Hair hygrometer
Hair hygrometers work on the basis of normal hair and its properties. Hair can change its length at different humidity levels. It is stretched on a plate or frame and, lengthening or shortening, moves the arrow, which in turn moves along the scale of the device.
A hair hygrometer is good for home use if you don't need to get extremely accurate readings.
Also, they should not be moved or mechanically acted upon in any other way. At the slightest impact, the hygrometer can fail, since its entire design is quite fragile and delicate.
Weight hygrometer
An absolute weight hygrometer consists of several tubes brought into the system. They contain a hygroscopic substance that can absorb moisture from the air.
A certain portion of air is drawn through the entire system, taken at one point in space.
So, a person determines the mass of the tube system before and after passing air through it, as well as directly the volume of air carried out and, with simple mathematical manipulations, can calculate the studied indicator in absolute terms.
Mechanical (ceramic) hygrometer
A porous or solid ceramic mass, which also includes metal elements, has electrical resistance. Its level is directly dependent on humidity.
For its correct action, the ceramic mass must consist of some metal oxides. Kaolin, silicon and clay are used as the basis.
Condensation hygrometer
This hygrometer is quite easy to use. The principle of its operation is based on the use of a built-in mirror. The temperature of this mirror changes along with the temperature of the air in the surrounding space.
Its temperature is determined at the initial moment of measurement. Further, drops of moisture or small ice crystals appear on the surface of the mirror. The temperature is measured again.
With the help of the temperature difference determined by the condensation hygrometer, the humidity of the air is determined.
Electronic hygrometer
A layer of lithium chloride is applied to a plate of glass or other similar electrically insulating material.
Humidity changes - the concentration and resistance of lithium chloride increases or decreases.
It is worth noting that the readings of an electronic (electrolytic) hygrometer can be slightly affected by air temperature, so it is often equipped with a built-in thermometer.
Such a hygrometer is extremely accurate and gives readings with a minimum error.
Psychrometric hygrometer (psychrometer)
The psychrometer is a system of two conventional alcohol thermometers. One of them is dry, and the second is wet (this state is regularly maintained).
The faster the moisture evaporates, the lower the relative humidity. The condensed liquid then begins to cool. Thus, the difference between the temperatures of two thermometers and the rate of evaporation are established, and on their basis the humidity of the air is found.
The psychrometer is not a hygrometer in the literal sense, but it measures the same indicator, so they are often identified.
Annex 3
Types and characteristics of air humidifiers:
1. "Traditional" or cold-type humidifiers are the simplest. Such devices are equipped with a tank into which water is poured, then it enters the tray on special moisturizing replaceable cartridges. The fan, which is built into such a humidifier, drives air through these cartridges and humidifies it naturally.
Most models of traditional humidifiers can also be used for aromatherapy. For this, a capsule with an aromatic substance is simply installed, and the device, while working, slowly begins to release and maintain a pleasant aroma. Such a procedure will not only improve the microclimate in the room, but will also have a tonic, relaxing and healing effect on the body.
But with all the ease of use and low cost, such humidifiers have their drawbacks. First of all, this is a limited maximum level of air humidity, up to 60% in total. Such devices, as it were, maintain “natural” humidity, but do not saturate the air forcibly. It is worth noting that for an ordinary apartment this drawback is very conditional. In addition, they are noisy, 35-40 dB are small numbers, but if you leave the device on overnight, it may cause discomfort for some.
Pros:
Quite simply, plus everything, there is also air purification from dust.
Small cost.
Easy to operate.
Can be used for aromatherapy.
Minuses:
Noise at work.
Limited hydration options.
Periodic filter change.
2. Steam humidifiers- these are a kind of small "trains", and according to the principle of operation they resemble electric kettles. You pour water into them, it heats up, boils and comes out in the form of steam, moistening the room. These humidifiers have many pros and cons.
Pros:
Works great with dirty and very hard water.
Possibility of use for inhalation (some models have special nozzles in the configuration).
High productivity (from 7 to 16 liters per day).
No consumables.
Humidification above 60%.
The possibility of using any solutions, including aroma oils.
Minuses:
High noise level.
High power consumption (from 300 to 600 W).
Hot burning steam (50-60 degrees at the outlet).
Big sizes.
Perhaps the formation of white plaque on the furniture.
If you have small children or animals in your house, and you have not yet decided which humidifier to choose, then steam is not the most best idea, because such a device can burn with steam.
3. The most modern air humidifiers can be called ultrasonic. They are equipped with a special membrane, which, thanks to the high frequency of oscillation, easily “turns” water into cold steam.
Such devices are almost silent in operation (25 dB), here it is possible to regulate the required level of humidity by yourself, and this is done both automatically and manually thanks to the built-in hygrometer. Many ultrasonic humidifiers come with a hygrometer that measures the humidity level, but unfortunately it doesn't give an accurate picture, so don't trust it too much, it's better to get a separate hygrometer for more reliable data.
Some models are equipped with a “water heating” function, and this is a death sentence for many microbes. A very good option, but keep in mind that "many" does not mean that all.
Ultrasonic devices are much more comfortable for a person than their counterparts, steam and traditional, as they have a low noise level.
The only thing that can cause discomfort is the rare “gurgling” of the cartridge, from which air bubbles come out.
Many models of such devices automatically turn off when water disappears, and the built-in hygrometer will allow the device to turn on and off on its own, thereby maintaining the desired humidity level, and the rotating spray can be directed in the right direction.
Such devices are equipped with a highly efficient cartridge filter that purifies water from various impurities and minerals, thereby preventing the formation of white deposits on furniture and other items, as is the case with the use of steam and traditional humidifiers. But the service life of the filters is short, about 3 months, depending on the contamination and hardness of the water, after which replacement is required.
Such devices, depending on the model, are equipped with either touch buttons or a rotary knob. Separately, it must be said about the safety of such devices for any living beings. Ultrasonic radiation is aimed at splitting water and is completely harmless to any biological life forms that live in your home.
Pros:
Noiseless at work.
Automatic humidity control.
Automatic shutdown in the absence of water.
Safety for animals in the house.
Automatic purification of water from impurities.
Wide range of humidity.
The ability to direct steam in any direction.
Do not leave a white coating on furniture.
Minuses:
More thorough care of the device.
The need to replace filter cartridges.
Price.
Appendix 4
Psychometric table
Annex 5
Dependence of pressure and density of saturated water vapor on temperature
|
Temperature t, °С |
Pressure pH, kPa |
Densityρ n, g / m 3 |
Temperature t, °С |
Pressure pH, kPa |
Densityρ n, g / m 3 |
