What does personal hygiene include? Staff hygiene standards

In this lesson, the concept of absolute and relative air humidity will be introduced, terms and quantities associated with these concepts will be discussed: saturated steam, dew point, instruments for measuring humidity. During the lesson we will get acquainted with the tables of density and saturated vapor pressure and the psychrometric table.

For humans, the amount of humidity is very important parameter environment, because our body reacts very actively to its changes. For example, a mechanism for regulating the functioning of the body, such as sweating, is directly related to the temperature and humidity of the environment. At high humidity, the processes of evaporation of moisture from the surface of the skin are practically compensated by the processes of its condensation and the removal of heat from the body is disrupted, which leads to disturbances in thermoregulation. At low humidity, moisture evaporation processes prevail over condensation processes and the body loses too much fluid, which can lead to dehydration.

The amount of humidity is important not only for humans and other living organisms, but also for the flow of technological processes. For example, due to the known property of water to conduct electric current its content in the air can seriously affect the correct operation of most electrical appliances.

In addition, the concept of humidity is the most important criterion assessments weather conditions, which everyone knows from weather forecasts. It is worth noting that if we compare humidity at different times of the year in our usual climatic conditions, then it is higher in summer and lower in winter, which is associated, in particular, with the intensity of evaporation processes at different temperatures.

The main characteristics of humid air are:

density of water vapor in the air;
relative humidity air.

Air is a composite gas and contains many different gases, including water vapor. To estimate its amount in the air, it is necessary to determine what mass water vapor has in a certain allocated volume - this value is characterized by density. The density of water vapor in the air is called absolute humidity.

Definition.Absolute air humidity- the amount of moisture contained in one cubic meter of air.

Designationabsolute humidity: (as is the usual designation for density).

Units of measurementabsolute humidity: (in SI) or (for the convenience of measuring small amounts of water vapor in the air).

Formula calculations absolute humidity:

Designations:

Mass of steam (water) in air, kg (in SI) or g;

The volume of air containing the indicated mass of steam is .

On the one hand, absolute air humidity is an understandable and convenient value, since it gives an idea of the specific water content in the air by mass; on the other hand, this value is inconvenient from the point of view of the susceptibility of humidity by living organisms. It turns out that, for example, a person does not feel the mass content of water in the air, but rather its content relative to the maximum possible value.

To describe such perception, the following quantity was introduced: relative humidity.

Definition.Relative humidity– a value indicating how far the steam is from saturation.

That is, the value of relative humidity, in simple words, shows the following: if the steam is far from saturation, then the humidity is low, if it is close, it is high.

Designationrelative humidity: .

Units of measurementrelative humidity: %.

Formula calculations relative humidity:

Designations:

Water vapor density (absolute humidity), (in SI) or ;

Density of saturated water vapor at a given temperature, (in SI) or .

As can be seen from the formula, it includes absolute humidity, with which we are already familiar, and saturated vapor density at the same temperature. The question arises: how to determine the latter value? For this there are special devices. We will consider condensationhygrometer(Fig. 4) - a device that is used to determine the dew point.

Definition.Dew point- the temperature at which steam becomes saturated.

Rice. 4. Condensation hygrometer ()

An easily evaporating liquid, for example, ether, is poured into the container of the device, a thermometer (6) is inserted, and air is pumped through the container using a bulb (5). As a result of increased air circulation, intense evaporation of ether begins, the temperature of the container decreases because of this, and dew (droplets of condensed steam) appears on the mirror (4). At the moment dew appears on the mirror, the temperature is measured using a thermometer; this temperature is the dew point.

What to do with the obtained temperature value (dew point)? There is a special table in which data is entered - what density of saturated water vapor corresponds to each specific dew point. It should be noted useful fact, that as the dew point increases, the value of the corresponding saturated vapor density also increases. In other words, the warmer the air, the greater the amount of moisture it can contain, and vice versa, the colder the air, the lower the maximum vapor content in it.

Let us now consider the principle of operation of other types of hygrometers, devices for measuring humidity characteristics (from the Greek hygros - “wet” and metreo - “I measure”).

Hair hygrometer(Fig. 5) - a device for measuring relative humidity, in which hair, for example human hair, acts as an active element.

The action of a hair hygrometer is based on the property of defatted hair to change its length when air humidity changes (with increasing humidity, the length of the hair increases, with decreasing it decreases), which makes it possible to measure relative humidity. The hair is stretched over a metal frame. The change in hair length is transmitted to the arrow moving along the scale. It should be remembered that a hair hygrometer does not give accurate relative humidity values, and is used primarily for domestic purposes.

A more convenient and accurate device for measuring relative humidity is a psychrometer (from the ancient Greek ψυχρός - “cold”) (Fig. 6).

A psychrometer consists of two thermometers, which are fixed on a common scale. One of the thermometers is called a wet thermometer because it is wrapped in cambric fabric, which is immersed in a reservoir of water located on the back of the device. Water evaporates from the wet fabric, which leads to cooling of the thermometer, the process of reducing its temperature continues until the stage is reached until the steam near the wet fabric reaches saturation and the thermometer begins to show the dew point temperature. Thus, the wet bulb thermometer shows a temperature less than or equal to the actual ambient temperature. The second thermometer is called a dry thermometer and shows the real temperature.

On the body of the device, as a rule, there is also a so-called psychrometric table (Table 2). Using this table, you can determine the relative humidity of the surrounding air from the temperature value shown by the dry bulb thermometer and from the temperature difference between the dry and wet bulb bulbs.

However, even without such a table at hand, you can approximately determine the amount of humidity using the following principle. If the readings of both thermometers are close to each other, then the evaporation of water from the humid one is almost completely compensated by condensation, i.e., the air humidity is high. If, on the contrary, the difference in thermometer readings is large, then evaporation from the wet fabric prevails over condensation and the air is dry and humidity is low.

Let's turn to the tables that allow you to determine the characteristics of air humidity.

Temperature,	Pressure, mm. rt. Art.	Vapor density

Table 1. Density and pressure of saturated water vapor

Let us note once again that, as stated earlier, the value of the density of saturated steam increases with its temperature, the same applies to the pressure of saturated steam.

Table 2. Psychometric table

Let us recall that relative humidity is determined by the value of the dry bulb readings (first column) and the difference between the dry and wet readings (first row).

In today's lesson we learned about an important characteristic of air - its humidity. As we have already said, humidity decreases in the cold season (winter) and increases in the warm season (summer). It is important to be able to regulate these phenomena, for example, if it is necessary to increase humidity, place the room in winter time several reservoirs of water to enhance evaporation processes, however, this method will only be effective at the appropriate temperature, which is higher than outside.

In the next lesson we will look at what gas work is and the principle of operation of an internal combustion engine.

References

Gendenshtein L.E., Kaidalov A.B., Kozhevnikov V.B. / Ed. Orlova V.A., Roizena I.I. Physics 8. - M.: Mnemosyne.
Peryshkin A.V. Physics 8. - M.: Bustard, 2010.
Fadeeva A.A., Zasov A.V., Kiselev D.F. Physics 8. - M.: Enlightenment.

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Internet portal “baroma.ru” ()
Internet portal “femto.com.ua” ()
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Homework

One of the very important indicators in our atmosphere. It can be either absolute or relative. How is absolute humidity measured and what formula should be used for this? You can find out about this by reading our article.

Air humidity - what is it?

What is humidity? This is the amount of water contained in any physical body or environment. This indicator directly depends on the very nature of the medium or substance, as well as on the degree of porosity (if we're talking about about solids). In this article we will talk about a specific type of humidity - air humidity.

From a chemistry course, we all know very well that atmospheric air consists of nitrogen, oxygen, carbon dioxide and some other gases, which make up no more than 1% of total mass. But in addition to these gases, the air also contains water vapor and other impurities.

Air humidity is understood as the amount of water vapor that is currently (and in a given place) contained in the air mass. At the same time, meteorologists distinguish two of its values: absolute and relative humidity.

Air humidity is one of the most important characteristics of the Earth's atmosphere, which affects the nature of local weather. It is worth noting that the amount of atmospheric air humidity is not the same - both in the vertical section and in the horizontal (latitudinal) section. So, if in the polar latitudes the relative air humidity (in bottom layer atmosphere) are about 0.2-0.5%, then in tropical areas - up to 2.5%. Next, we will find out what absolute and relative air humidity is. We will also consider what difference exists between these two indicators.

Absolute humidity: definition and formula

Translated from Latin, the word absolutus means “full”. Based on this, the essence of the concept of “absolute air humidity” becomes obvious. This is a value that shows how many grams of water vapor are actually contained in one cubic meter of a particular air mass. As a rule, this indicator is denoted by the Latin letter F.

G/m 3 is a unit of measurement in which absolute humidity is calculated. The formula for calculating it is as follows:

In this formula, the letter m denotes the mass of water vapor, and the letter V denotes the volume of a specific air mass.

The value of absolute humidity depends on several factors. First of all, these are air temperature and the nature of advection processes.

Relative humidity

Now let's look at what relative humidity is. This is a relative value that shows how much moisture is contained in the air in relation to the maximum possible amount of water vapor in that air mass at a particular temperature. Relative air humidity is measured as a percentage (%). And it is precisely this percentage that we can often find out in weather forecasts and weather reports.

It is also worth mentioning such an important concept as dew point. This is the phenomenon of the maximum possible saturation of the air mass with water vapor (the relative humidity at this moment is 100%). In this case, excess moisture condenses and precipitation, fog or clouds form.

Methods for measuring air humidity

Women know that they can detect increased humidity in the atmosphere with the help of their voluminous hairstyle. However, there are other, more accurate, methods and technical devices. These are a hygrometer and a psychrometer.

The first hygrometer was created back in the 17th century. One of the types of this device is precisely based on the properties of hair to change its length with changes in environmental humidity. However, today there are also electronic hygrometers. A psychrometer is a special device that contains a wet and dry thermometer. Based on the difference in their indicators, air humidity is determined at a specific point in time.

Air humidity as an important environmental indicator

It is considered optimal for human body is the relative air humidity of 40-60%. Humidity indicators also greatly influence a person’s perception of air temperature. So, with low humidity, it seems to us that the air is much colder than in reality (and vice versa). That is why in the tropical and equatorial latitudes of our planet, travelers experience the heat and heat so hard.

Today there are special humidifiers and dehumidifiers that help a person regulate air humidity in enclosed spaces.

In conclusion...

Thus, absolute air humidity is the most important indicator, which gives us an idea of the state and characteristics of air masses. In this case, you need to be able to distinguish this value from relative humidity. And if the latter shows the proportion of water vapor (in percent) that is present in the air, then absolute humidity is the actual amount of water vapor in grams in one cubic meter of air.

For humans, the humidity level is a very important environmental parameter, since our body reacts very actively to its changes. For example, a mechanism for regulating the functioning of the body, such as sweating, is directly related to the temperature and humidity of the environment. At high humidity, the processes of evaporation of moisture from the surface of the skin are practically compensated by the processes of its condensation and the removal of heat from the body is disrupted, which leads to disturbances in thermoregulation. At low humidity, moisture evaporation processes prevail over condensation processes and the body loses too much fluid, which can lead to dehydration.

The amount of humidity is important not only for humans and other living organisms, but also for the flow of technological processes. For example, due to the known property of water to conduct electric current, its content in the air can seriously affect the correct operation of most electrical appliances.

In addition, the concept of humidity is the most important criterion for assessing weather conditions, which everyone knows from weather forecasts. It is worth noting that if we compare humidity at different times of the year in our usual climatic conditions, it is higher in summer and lower in winter, which is associated, in particular, with the intensity of evaporation processes at different temperatures.

The main characteristics of humid air are:

density of water vapor in the air;
relative air humidity.

Definition.Absolute air humidity- the amount of moisture contained in one cubic meter of air.

Designationabsolute humidity: (as is the usual designation for density).

Units of measurementabsolute humidity: (in SI) or (for the convenience of measuring small amounts of water vapor in the air).

Formula calculations absolute humidity:

Designations:

Mass of steam (water) in air, kg (in SI) or g;

The volume of air containing the indicated mass of steam is .

To describe such perception, the following quantity was introduced: relative humidity.

Definition.Relative humidity– a value indicating how far the steam is from saturation.

That is, the value of relative humidity, in simple words, shows the following: if the steam is far from saturation, then the humidity is low, if it is close, it is high.

Designationrelative humidity: .

Units of measurementrelative humidity: %.

Formula calculations relative humidity:

Designations:

Water vapor density (absolute humidity), (in SI) or ;

Density of saturated water vapor at a given temperature, (in SI) or .

As can be seen from the formula, it includes absolute humidity, with which we are already familiar, and saturated vapor density at the same temperature. The question arises: how to determine the latter value? There are special devices for this. We will consider condensationhygrometer(Fig. 4) - a device that is used to determine the dew point.

Definition.Dew point- the temperature at which steam becomes saturated.

Rice. 4. Condensation hygrometer ()

What to do with the obtained temperature value (dew point)? There is a special table in which data is entered - what density of saturated water vapor corresponds to each specific dew point. It is worth noting a useful fact that as the dew point increases, the value of the corresponding saturated vapor density also increases. In other words, the warmer the air, the greater the amount of moisture it can contain, and vice versa, the colder the air, the lower the maximum vapor content in it.

Let us now consider the principle of operation of other types of hygrometers, devices for measuring humidity characteristics (from the Greek hygros - “wet” and metreo - “I measure”).

Hair hygrometer(Fig. 5) - a device for measuring relative humidity, in which hair, for example human hair, acts as an active element.

A more convenient and accurate device for measuring relative humidity is a psychrometer (from the ancient Greek ψυχρός - “cold”) (Fig. 6).

Let's turn to the tables that allow you to determine the characteristics of air humidity.

Temperature,	Pressure, mm. rt. Art.	Vapor density

Table 1. Density and pressure of saturated water vapor

Let us note once again that, as stated earlier, the value of the density of saturated steam increases with its temperature, the same applies to the pressure of saturated steam.

Table 2. Psychometric table

Let us recall that relative humidity is determined by the value of the dry bulb readings (first column) and the difference between the dry and wet readings (first row).

In today's lesson we learned about an important characteristic of air - its humidity. As we have already said, humidity decreases in the cold season (winter) and increases in the warm season (summer). It is important to be able to regulate these phenomena, for example, if it is necessary to increase humidity, place several reservoirs of water indoors in winter in order to enhance evaporation processes, however, this method will only be effective at the appropriate temperature, which is higher than outside.

In the next lesson we will look at what gas work is and the principle of operation of an internal combustion engine.

References

Gendenshtein L.E., Kaidalov A.B., Kozhevnikov V.B. / Ed. Orlova V.A., Roizena I.I. Physics 8. - M.: Mnemosyne.
Peryshkin A.V. Physics 8. - M.: Bustard, 2010.
Fadeeva A.A., Zasov A.V., Kiselev D.F. Physics 8. - M.: Enlightenment.

Internet portal “dic.academic.ru” ()
Internet portal “baroma.ru” ()
Internet portal “femto.com.ua” ()
Internet portal “youtube.com” ()

Homework

Water in the atmosphere occurs in the form of steam, ice, snowflakes and water droplets. Water vapor content in the air - important characteristic weather and climate. The higher the air temperature, the more steam it can contain. So at plus 20°C one cubic meter air can contain 17 grams of water vapor, at minus 20°C - only one gram.

Air humidity is characterized by several indicators:

a) absolute humidity (“absolut” in Latin means “complete”) is the amount of water vapor contained in the air. Absolute humidity is expressed either in 1 g/m3 or in air pressure units ( cm.), which show the pressure that steam would produce if it alone occupied the volume of all the air - the so-called partial pressure. In equatorial latitudes, absolute air humidity can reach 30 g/m3. Towards the poles the indicator decreases to 0.1;

b) relative humidity shows the ratio of the amount of water vapor contained in the air to the largest amount that can be contained at a given temperature. Data are expressed as percentages. For example, relative humidity is 70 percent. This means that the air contains 70 percent of the water vapor it can hold at a given temperature. A person feels good at a relative humidity of 40-75 percent. Deviation from the norm causes a feeling of discomfort.

In nature, air cannot exist without water vapor; it always contains some amount of it. There is no place on Earth where zero relative humidity has been recorded. The highest relative humidity is 100 percent during fog.

Depending on the water vapor content, saturated and unsaturated air are distinguished. Air that can no longer hold moisture is called saturated air. At the slightest cooling, precipitation falls from this air in the form of dew or fog. This happens because water, when cooled, moves from gaseous state(water vapor) into liquid - the process is called condensation (from the Latin “condensation”). The temperature at which water vapor saturates the air and condensation begins is called the dew point.

Air above a dry, warm surface usually contains less water vapor than it would at a given temperature. Such air is called unsaturated. When it cools, precipitation is not always released.

Calculation of air humidity has great value not only for determining the weather, but also for carrying out technical activities, storing books and museum paintings, treating many diseases, and irrigating fields.

1. Department of Radiochemistry, Faculty of Chemistry, Moscow State University named after M.V. Lomonosov Lecture “Behavior, hygiene and clothing of personnel working in clean rooms” Bochagin Philipp Sergeevich Leading specialist of the Quality Assurance Department Plant “Medradiopreparat” branch of the Federal State Unitary Enterprise “Federal Center for Design and Development of Facilities” nuclear medicine» FMBA of Russia [email protected] Date May 21, 2013 1
2. Lecture structure 1. 2. 3. 4. 5. Requirements for personnel Personal hygiene Behavior of personnel in clean rooms Health requirements Clothing for clean rooms 2
3. 1. Requirements for personnel Persons who have access to clean rooms must:  Observe the requirements of personal hygiene  Follow the rules of conduct in clean rooms  Have contraindications to work in clean rooms due to health reasons  Complete a training course before being allowed to work, and then undergo repeated periodic training  Strictly follow all instructions and regulations  Positive attitude of staff towards maintaining cleanliness 3
4. 2. Personal hygiene Requirements for personal hygiene are elementary. However, their exact implementation is a stumbling block for individuals. Everyone who has access to a clean room is obliged to:  Wash their hands before entering a clean room, and before entering sterile areas, wash their arms up to the elbows  Wash their hands after using the toilet  Avoid vulgar manners, in particular, do not wipe their nose with their fingers  Monitor the cavity mouth and brush your teeth regularly  Dress cleanly, especially when going to work  Remove cosmetics (mascara, powder, lipstick, nail polish, etc.) before entering clean rooms, as they emit contaminants and create a favorable environment for reproduction of microorganisms  Remove jewelry, because they have many hidden places where pollution can accumulate 4
5. 3. Conduct of personnel in clean rooms The main principle that determines the rules for the behavior of personnel in clean rooms is not to allow anything that could introduce contamination into the clean room.  You must move slowly in a clean room, avoiding unnecessary movements (scratching, rubbing hands, face and other parts of the body, gesturing)  It is forbidden to drink, smoke, read newspapers and magazines, carry drinks, chewing gum, medicines, matches, lighters, cigarettes , stationery, wristwatches  You can’t talk or shout loudly in a clean room  You can’t lean over the workplace, lean against walls and equipment, or carry objects by holding them close to you  When coughing and sneezing, you should turn away from the work area 5
6. 4. Health requirements Personnel should not be admitted in cases of:  The presence of an acute or chronic disease in which the release of pollution increases (acute respiratory diseases, conjunctivitis, upper respiratory tract diseases, skin diseases, herpes, boils, seborrhea, etc. )  Presence of coughing, sneezing, discharge from the nose and eyes  Increased sweating, damage skin as a result of injuries, sunburn etc. The oral cavity must be sanitized. At the slightest sign of illness, the employee must report his condition to his immediate supervisor without waiting for the end of the work shift 6
7. 5. Clothing for clean rooms Purpose of clothing for clean rooms:  To protect the technological process, product and environment from contamination emitted by humans  To protect people from harmful influence environment, including technological process, materials and production products used in it  Create comfortable conditions for personnel GOST R 52538-2006 Clean rooms. Technological clothing. General requirements The requirements of this standard apply to clothing for clean rooms used in various industries, healthcare, etc. The standard establishes requirements for clothing based on the protection of the air environment of clean rooms, the technological process and the product from contaminants emitted by humans. 7