An effective remedy Industrial ventilation ensures proper cleanliness and acceptable parameters of the air microclimate in the working area.

Ventilation is an organized and regulated air exchange that ensures the removal of polluted air from a room and the supply of fresh air in its place.

By way of air movement There are natural and mechanical ventilation systems.

A ventilation system in which the movement of air masses is carried out due to the resulting pressure difference between the outside and inside the building is called natural ventilation.

When the wind acts on the surfaces of a building on the leeward side, excess pressure is formed, and on the windward side - a vacuum. The distribution of pressure over the surface of buildings and their magnitude depend on the direction and strength of the wind, as well as on the relative position of the buildings.

Unorganized natural ventilation - infiltration , or natural ventilation - carried out by changing the air in the rooms through leaks in fences and elements building structures due to the difference in pressure outside and inside the room. Infiltration can be significant for residential buildings and reach 0.5 - 0.75 room volume per hour, and for industrial enterprises up to 1 - 1.5.

For constant air exchange required by the conditions for maintaining clean air in the room, it is necessary organized ventilation . Organized natural ventilation can be:

Exhaust without organized air flow (duct);

Supply and exhaust with organized air flow (duct and non-duct aeration).

Channel natural exhaust ventilation without organized air flow is widely used in residential and administrative buildings

Aeration is called organized natural general ventilation premises as a result of the entry and removal of air through opening transoms of windows and skylights.

As a method of ventilation, aeration has found wide application in industrial buildings, characterized by technological processes with large heat releases. Entrance of outside air into cold period years are organized so that cold air didn't get into work area. For this outside air served into the room through openings located at least 4.5 m from the floor. During the warm season, the influx of outside air is oriented through the lower tier of window openings.

When calculating aeration, the requirements of SNiP 2.04.05-91 are used.

The main advantage of aeration is the ability to carry out large air exchanges without the expenditure of mechanical energy.

To the disadvantages of aeration It should be noted that during the warm period of the year, the efficiency of aeration can drop significantly due to an increase in the temperature of the outside air and, in addition, the air entering the room is not cleaned or cooled.

Ventilation, by which air is supplied to or removed from production premises through systems ventilation ducts using special mechanical stimuli for this, called mechanical ventilation .

Mechanical ventilation has a number of advantages:

Large radius of action due to the significant pressure created by the fan;

The ability to change or maintain the required air exchange regardless of the outside temperature and wind speed;

Subject the air introduced into the room to pre-cleaning, drying or humidification, heating or cooling;

Organize optimal air distribution with air supply directly to workplaces;

Capture harmful emissions directly at the places of their formation and prevent their spread throughout the entire volume of the room, as well as the ability to purify polluted air before releasing it into the atmosphere.

Disadvantages of mechanical ventilation The significant cost of the structure and its operation and the need for noise control measures should be taken into account.

Mechanical ventilation systems are divided into:

1. General exchange.

2. Local.

3. Mixed.

4. Emergency.

5. Air conditioning systems.

General ventilation designed to assimilate excess heat, moisture and harmful substances throughout the entire working area of ​​the premises. It is used if harmful emissions enter directly into the air of the room; workplaces are not fixed, but are located throughout the room.

Based on the method of air supply and removal, four general ventilation schemes are distinguished:

Supply;

Exhaust;

Supply and exhaust;

Recirculation systems.

According to the supply system air is supplied to the room after it has been prepared in the supply chamber. This creates excess pressure in the room, due to which the air escapes outside through windows, doors or into other rooms. The supply system is used to ventilate rooms into which it is undesirable for polluted air from neighboring rooms or cold air from outside to enter.

Exhaust system designed to remove air from the room. At the same time, a reduced pressure is created in it and the air from neighboring rooms or outside air enters this room.

Supply and exhaust ventilation - the most common system in which air is supplied to the room supply system, and the exhaust is removed.

In some cases, to reduce operating costs for air heating, ventilation systems with partial recirculation are used. In them, the air sucked from the room by the exhaust system is mixed with the air coming from outside. The amount of fresh and secondary air is controlled by valves . The ventilation system with recirculation is allowed to be used only for those rooms in which there are no emissions of harmful substances.

In a normal microclimate and the absence of harmful emissions, the amount of air during general ventilation is taken depending on the volume of the room per worker.

By using local ventilation the necessary meteorological parameters are created at individual workplaces. Local exhaust ventilation is the most widely used. The main method of combating harmful secretions is to install and organize suction from shelters.

Local suction designs can be completely closed, semi-open or open.

Closed suctions are the most effective. These include casings and chambers that hermetically or tightly cover technological equipment .

If it is impossible to arrange such shelters, then use suction with partial shelter or open: exhaust hoods, suction panels, fume hoods, side suction, etc.

One of the most simple types local suctions - exhaust hood. It serves to trap harmful substances that have a lower density than the surrounding air.

The required air exchange in local exhaust ventilation devices is calculated based on the localization conditions of impurities released from the source of formation.

Mixed ventilation system is a combination of elements of local and general ventilation. Local system removes harmful substances from casings and covers of machines. However, some harmful substances penetrate into the room through leaks in shelters. This part is removed by general ventilation.

Emergency ventilation is provided in those production premises in which a sudden entry into the air is possible large quantity harmful or explosive substances.

To create optimal meteorological conditions in industrial premises, the most advanced type of industrial ventilation is used - air conditioning.

Air conditioning is called its automatic processing in order to maintain predetermined meteorological conditions in production premises, regardless of changes in external conditions and indoor conditions.

When air conditioning, the air temperature, its relative humidity and the rate of supply to the room are automatically adjusted depending on the time of year, external meteorological conditions and the nature of the technological process in the room.

Such strictly defined air parameters are created in special installations called air conditioners. In some cases, in addition to providing sanitary standards The air microclimate in air conditioners is subject to special treatment: ionization, deodorization, ozonation, etc.

Air conditioners can be:

1. Local (for servicing individual premises).

2. Central (for servicing several separate premises).

Air conditioning plays an essential role not only from the point of view of life safety, but also in many technological processes in which fluctuations in temperature and air humidity are not allowed (especially in radio electronics). Therefore, air conditioning installations in last years are increasingly used in industrial enterprises.

Fig. 4.3. Air supply diagrams: diagrams a - from top to bottom; b - from top to top; c - from bottom to top; g - from bottom to bottom Rice. 4.2. Pressure distribution in a building Rice. 4.4. Supply ventilation diagram: 1 - device in the form of a channel or shaft; 2 - filter for air purification; 3 - bypass channel; 4 - air heater; 5 - air duct network; 6 - fan; 7 - supply pipes with nozzles Rice. 4.5. Schemes of supply nozzles: a, b - for vertical supply; c, d - for one-sided feeding at different angles; d - for concentrated inclined feed; f, g - for scattered horizontal feed Rice. 4.6. Scheme exhaust ventilation: 1 - air purification device; 2 - fan; 3 - central air duct; 4 - suction air ducts Rice. 4.7. Supply and exhaust ventilation: 1 - shaft; 2 - filter for air purification; 3 - bypass channel; 4 - air heater; 5 - air ducts; 6 - fan; 7 - supply pipes with nozzles Rice. 4.8. Supply and exhaust ventilation with recirculation: 1 - shaft; 2 - filter for air purification; 3 - bypass channel; 4 - air heater; 5 - air ducts; 6 - fan; 7 - supply pipes with nozzles; 8 - exhaust pipes with nozzles; 9 - valve Rice. 4.9. Air curtains: a - with bottom air supply; b - with lateral two-way air supply; c - with one-way air supply; d - detail of the slot; H, B - height and width of gates (doors), respectively; b - slot width Rice. 4.11. Fume hoods: a - with upper suction; b - with lower suction; c, d - with combined suction Rice. 4.10. Local suctions: a - umbrella; b - overturned umbrella; c - suction panel Rice. 4.12. Onboard suction: a - to remove volatile vapors; b - to remove heavy vapors Rice. 4.13. Cyclone TsN-15 NIIOGAZ: 1 - bunker; 2 - metal cylinder; 3 - pipe; 4 - pipe

Per condition human body big influence influence meteorological conditions (microclimate) in production premises.

In accordance with GOST 12.1.005-88 microclimate of industrial premises is determined by the combinations of temperature, humidity and air speed acting in them on the human body, as well as the temperature of the surrounding surfaces.

If work is carried out in open areas, then meteorological conditions are determined climatic conditions and season of the year.

Air temperature- a parameter characterizing its thermal state, i.e. kinetic energy molecules of gases included in its composition. Temperature is measured in degrees Celsius or Kelvin.

The temperature regime of the room depends on the formula "src="http://hi-edu.ru/e-books/xbook908/files/tp, these two factors determine the convective and radiation heat exchange of a person and environment. To assess the influence of temperatures of heated surfaces, the concept of radiation temperature is introduced. Roughly it can be defined as follows:

Gif" border="0" align="absmiddle" alt=".

Joint influence formula" src="http://hi-edu.ru/e-books/xbook908/files/tp.gif" border="0" align="absmiddle" alt=".gif" border="0" align="absmiddle" alt="

In most cases, for ordinary premises the formula" src="http://hi-edu.ru/e-books/xbook908/files/tp.gif" border="0" align="absmiddle" alt=".gif" border="0" align="absmiddle" alt=".

Under atmospheric pressure refers to a quantity characterized by column pressure atmospheric air per single surface. Normal pressure is considered to be 1013.25 hPa (hectopascal, very rarely used in practice) or 760 mm. rt. Art. (1 hPa =
= 100 Pa = 3/4 mm. rt. Art.).

Atmospheric air consists of a mixture of dry gases and water vapor, i.e. we always deal with moist air or a steam-air mixture. Moreover, water vapor can be either in a superheated or saturated state. To characterize the moisture content in the air, the concepts of absolute and relative humidity.

Absolute air humidity is the mass of water vapor contained in 1 mark"> Air mobility. A person begins to feel the movement of air at a speed of approximately 0.1 m/s. At normal temperatures, light air movement, blowing away the steam-saturated and superheated layer of air enveloping a person, promotes good health. At the same time, in conditions low temperatures, high air speed causes an increase in heat loss by convection and evaporation and leads to severe cooling of the body.

All life processes in the human body are accompanied by the formation of heat, the amount of which varies from 80 J/s (at rest) to 700 J/s (when performing heavy physical work).

Despite the fact that the factors that determine the indoor microclimate can vary greatly within wide limits, the human body temperature remains, as a rule, at a constant level (36.6 mark "> Weather conditions, in which there are no unpleasant sensations and tension in the thermoregulatory system are called comfortable (optimal) conditions.

Meteorological conditions are perceived by a person as comfortable only when the amount of heat generated by the body is equal to the total heat transfer to the environment, i.e. while maintaining thermal balance.

Heat exchange organism with the environment can occur in various ways: convective transfer of heat to the surrounding air (in normal conditions up to 5% of all heat removed); radiant heat exchange with surrounding surfaces (40%); contact thermal conductivity through contacting surfaces (30%); evaporation of moisture from the surface of the skin (20%); due to heating of exhaled air (5%).

When the air temperature drops, to reduce heat transfer, the body reduces the temperature of the skin, reduces the moisture content of the skin, thereby reducing heat transfer. When the air temperature rises blood vessels the skin expands, there is an increased blood flow to the surface of the body, and heat transfer to the environment increases significantly..gif" border="0" align="absmiddle" alt="With significant thermal radiation from heated surfaces, the body's thermoregulation is disrupted. This can lead to overheating, especially if moisture loss approaches 5 liters per shift. In this case, there is increasing weakness, headache, tinnitus, distortion of color perception (everything turns red or green), nausea, vomiting, and increased body temperature. Breathing and pulse quicken, blood pressure first increases, then falls. In severe cases, heat stroke occurs. A convulsive disease is possible, which is a consequence of a violation of the water-salt balance and is characterized by weakness, headache, and sudden cramps of the limbs.

But further, if such painful conditions do not occur, overheating of the body greatly affects the state of the nervous system and human performance. It has been established that with a 5-hour stay in an area with an air temperature of 31 hint ">, neuritis, radiculitis, etc., as well as colds. Any degree of cooling is characterized by a decrease in heart rate and the development of inhibition processes in the cerebral cortex, which leads to a decrease In particularly severe cases, exposure to low temperatures can lead to frostbite and even death.

Different combinations of microclimate parameters, having a complex effect on a person, can cause the same thermal sensations. This is the basis for the introduction of the so-called effective and effective-equivalent temperatures. Effective temperature characterizes a person's sensations when exposed to temperature and air movement simultaneously. The effective equivalent temperature also takes into account air humidity. The effective temperature and comfort zone can be determined using a nomogram constructed empirically(Fig. 4.1 ).

Excess heat, moisture release, thermal radiation, and high air mobility worsen the microclimate of industrial premises, complicate thermoregulation, adversely affect the body of workers and contribute to a decrease in productivity and quality of work.

Air contaminated with harmful gases, vapors and dust poses a risk of poisoning or occupational diseases, causes increased fatigue, and, as a consequence, increases the risk of injury.

From a physiological point of view, air should be considered from two positions: as air inhaled by a person, and as a medium surrounding a person. The role of air, accordingly, is to supply the body with oxygen, remove moisture during exhalation and ensure heat exchange between a person and the environment. Air is also a working agent that removes dust, moisture, and harmful emissions from the room.

Sanitary standards set values optimal parameters microclimate at workplaces (Table 4.1).

Table 4.1

Optimal microclimate parameters 5 in workplaces
(SanPiN 2.2.4.548-96)

5 Relative air humidity for all seasons and categories

PRACTICAL LESSON No. 4

Subject

“CALCULATION OF REQUIRED AIR EXCHANGE DURING GENERAL VENTILATION”

Target: To become familiar with the methodology for calculating the required air exchange rate for designing general ventilation in industrial premises.

General information

In order to maintain in the workshops optimal conditions microclimate and prevention of emergency situations (mass poisonings, explosions), to remove harmful gases, dust and moisture is installed ventilation. Ventilation is an organized, controlled air exchange that ensures the removal of polluted air from a room and the supply of fresh air in its place. Depending on the method of air movement, ventilation can be natural or mechanical.

Natural – ventilation, the movement of air masses in which is carried out due to the resulting pressure difference outside and inside the building.

Mechanical– ventilation, with the help of which air is supplied to or removed from the production room through a system of ventilation ducts due to the operation of a fan. It allows you to maintain constant temperature and humidity in work areas.

Depending on the method of organizing air exchange, ventilation is divided into local, general exchange, mixed and emergency.

General ventilation – designed to remove excess heat, moisture and harmful substances throughout the entire working area of ​​the premises. She creates the conditions air environment, identical throughout the entire volume of the ventilated room, and is used if harmful emissions enter directly into the air of the room; workplaces are not fixed, but are located throughout the room.

Depending on production requirements and sanitary and hygienic rules, the supply air can be heated, cooled, humidified, and the air removed from the premises can be cleaned of dust and gas. Typically, the volume of air L in supplied to the room during general ventilation is equal to the volume of air L in removed from the room.

The proper organization and design of supply and exhaust systems has a significant impact on the parameters of the air environment in the work area.

1. Methodology for calculating the required air exchange during general ventilation.

With general ventilation, the required air exchange is determined from the conditions for removing excess heat, removing excess moisture, removing poisonous and harmful gases, as well as dust.

In a normal microclimate and the absence of harmful emissions, the amount of air during general ventilation is taken depending on the volume of the room per worker. The absence of harmful emissions is considered to be such amounts in the process equipment, with the simultaneous release of which in the air of the room the concentration of harmful substances will not exceed the maximum permissible. At the same time, the maximum permissible concentrations of harmful and toxic substances in the air of the working area must comply with GOST 12.1.005 - 91.

If in a production room the volume of air for each worker is V pr i< 20м 3 , то расход воздуха L i должен быть не менее 30м 3 на каждого работающего. Если V пр i = 20 … 40м 3 , то L i ≥ 20м 3 / ч. В помещениях с V пр i >40m3 and in the presence of natural ventilation, air exchange is not calculated. In the absence of natural ventilation, the air flow per worker must be at least 60m3/h.

To qualitatively assess the efficiency of air exchange, the concept of air exchange rate K is adopted - the ratio of the volume of air entering the room per unit of time L (m 3 / h) to the free volume of the ventilated room V s (m 3). With proper organization of ventilation, the air exchange rate should be significantly greater than one.

Required air exchange for the entire production area as a whole:

L pp = n · L i ; (1)

Where n is the number of workers in a given room.

In this practical work, we will calculate the required air exchange rate for cases of removing excess heat and removing harmful gases.

A. Necessary air exchange to remove excess heat .

Where L 1 is the air exchange necessary to remove excess heat (m 2 / h);

Q – excess amount of heat, (kJ/h);

c – heat capacity of air, (J / (kg 0 C), c = 1 kJ/kg K;

ρ – air density, (kg/m3);

(3)

Where tpr – supply air temperature, (0 C); It depends on the geographical location of the plant. For Moscow – is taken equal to 22.3 0 C.

Tух – the temperature of the air leaving the room is assumed to be equal to the air temperature in the work area, (0 C), which is taken to be 3 – 5 0 C higher than the calculated outside air temperature.

Excess heat to be removed from production premises, is determined by the heat balance:

Q = Σ Q pr – Σ Q exp; (4)

Where Σ Q pr – heat entering the room from various sources, (kJ / h);

Σ Q consumption - heat consumed by the walls of the building and leaving with heated materials, (kJ / h), is calculated according to the methodology set out in SNiP 2.04.05 - 86.

Since the difference in air temperatures inside and outside the building during the warm period of the year is small (3 - 5), when calculating air exchange based on excess heat generation, heat loss through building structures can be ignored. And a slightly increased air exchange will have a beneficial effect on the microclimate of the working room on the hottest days.

The main sources of heat generation in industrial premises are:

Hot surfaces (ovens, drying chambers, heating systems, etc.);

Cooled masses (metal, oils, water, etc.);

Equipment driven by electric motors;

Solar radiation;

Personnel working indoors.

To simplify calculations in this practical work, the excess amount of heat is determined only taking into account the heat generated by electrical equipment and operating personnel.

Thus: Q = ΣQ pr; (5)

ΣQ pr = Q e.o. + Q p; (6)

Where Q e.o. – heat generated during operation of equipment driven by electric motors, (kJ/h);

Q р – heat generated by working personnel, (kJ/h).

(7)

Where β is a coefficient that takes into account the equipment load, the simultaneity of its operation, and the operating mode. Taken equal to 0.25 ... 0.35;

N – total installed power of electric motors, (kW);

Q р – is determined by the formula: Q р = n · q р (8)

300 kJ/h – for light work;

400 kJ/h – when working avg. heaviness;

500 kJ/h – for heavy work.

q р – heat released by one

person, (kJ/h);

b. Necessary air exchange to maintain the concentration of harmful substances within specified limits.

When ventilation is operating, when there is equality in the masses of supply and exhaust air, it can be assumed that harmful substances do not accumulate in the production area. Consequently, the concentration of harmful substances in the air removed from the room q beat should not exceed the maximum permissible concentration.

The supply air flow rate, m 3 h, required to maintain the concentration of harmful substances within specified limits is calculated by the formula:
,(9)

Where G– amount of harmful substances released, mg/h, q beat– concentration of harmful substances in the removed air, which should not exceed the maximum permissible, mg/m3, i.e. q beat  q maximum permissible concentration ; q etc– concentration of harmful substances in supply air, mg/m3. The concentration of harmful substances in the supply air should not exceed 30% of the maximum permissible concentration, i.e. q etc  0,3q beat

V. Determining the required air exchange rate.

The value showing how many times the required air exchange is greater than the volume of air in the production room (determining the air change rate) is called the required air exchange rate. It is calculated by the formula:

K = L / V s; (10)

Where K is the required air exchange rate;

L – required air exchange, (m 3 / h). Determined by comparing the values ​​of L 1 and L 2 and choosing the largest of them;

V с – internal free volume of the room, (m 3). It is defined as the difference between the volume of the room and the volume occupied by the production equipment. If the free volume of the room cannot be determined, then it can be assumed to be conditionally equal to 80% of the geometric volume of the room.

The air exchange rate of industrial premises usually ranges from 1 to 10 (higher values ​​for rooms with significant emissions of heat, harmful substances or small in volume). For foundry, forging and pressing, thermal, welding, and chemical production shops, the air exchange rate is 2-10, for mechanical engineering and instrument making shops – 1-3.

One of the main means of collective protection of workers from negative impact harmful factors in the air environment (dust, gas contamination, increased heat and humidity) is ventilation.

Ventilation is a set of interconnected devices and processes designed to create an organized air exchange necessary to remove contaminated or overheated (cooled) air from the production area with the supply of clean and cooled (heated) air instead, which allows creating in the working area favorable conditions air environment.

The amount of air required to ensure the required air parameters in the work area is determined depending on the amount of harmful factors released in such a way as to ensure maximum permissible concentrations and levels.

Under ventilation system understand a set of ventilation units with different purposes that can serve separate room or building. The classification of the main types of ventilation is presented in Fig. P1.9.

Depending on the method of air movement in work areas, ventilation is divided into artificial (mechanical), natural and combined.

With natural ventilation, air exchange is carried out in two ways:

Unorganized (ventilation and air infiltration through window, door openings, cracks and microcracks);

Organized (through aeration and using deflectors).

Natural unorganized air exchange in a room is caused by the action of two factors: thermal air movement and wind pressure. Thermal movement is created by the difference in the weight of air columns outside and inside the room. Thus, a pressure difference occurs, which causes air exchange. Wind pressure is caused by the action of the wind, due to which excess pressure occurs on the windward surfaces of the building, and rarefaction occurs on the leeward sides. The resulting pressure difference causes air to enter from the windward side of the building and exit through openings on the opposite windward side. In some cases, unorganized air exchange is not enough to remove harmful emissions from the room, so a special device is used - a deflector (see Fig. A1.10). The deflector is the end of a pipe designed to remove air from the upper zone of the room. The wind flow, hitting the deflector and flowing around it, creates a vacuum that ensures air suction from the room through the deflector channel. Aeration is organized natural air exchange, carried out in pre-calculated volumes and regulated in accordance with external meteorological conditions.

The advantage of natural ventilation is the simplicity of the devices and minimal operating costs. The disadvantage is the influence of natural factors (wind, ambient temperature) on its effectiveness, as well as the fact that air is supplied and removed from the room that has not undergone special treatment (not cleared of dust and other harmful impurities, not refrigerated or heated). Therefore, natural ventilation is used mainly where there are no significant emissions of harmful factors.

At artificial ventilation air movement is activated mechanical devices. The classification of mechanical ventilation is shown in Fig. P1.11.

According to the nature of the room coverage ventilation systems can be general exchange, local (local) and combined.

With general ventilation, air change occurs throughout the entire volume of the room. This type of ventilation can be carried out either naturally (aeration) or mechanically.

The purpose of local ventilation is to localize harmful emissions in places of formation and remove them from the room. It can be carried out mechanically with the help of fans and naturally with the help of deflectors.

At combined system simultaneously with the general air exchange, the individual most intense sources of emissions are also localized.

Local ventilation can be supply or exhaust.

The supply air is provided for the purpose of supplying clean air to the work area to create a microclimate in individual places (air showers, curtains and oases). An air shower is a stream of air directed at a person. Air curtain helps prevent penetration into manufacture building through the cold air gate into winter time. Air oases improve weather conditions for limited area room, which is separated for this purpose on all sides light partitions and is flooded with air that is colder and cleaner than the air in the room.

Exhaust ventilation is installed in places where harmful emissions are formed in the form of cabinets, umbrellas, suction from various equipment, vacuum cleaners, dust collectors, ejection units, individual suction units, and so on.

General exchange mechanical ventilation It can be supply, exhaust, supply and exhaust, and can also be carried out using air conditioners. With forced general ventilation Fresh air is taken from places outside the building and distributed throughout the entire volume of the premises. Polluted air is displaced by fresh air through doors, windows, lanterns and cracks in building structures. Forced ventilation used in the presence of heat emissions and absence of gas emissions.

Exhaust general ventilation allows you to remove contaminated and overheated air from the entire volume of the room. To replace the removed air, clean air is sucked in from the outside through doors, windows, and cracks in building structures.

Supply and exhaust general exchange mechanical ventilation consists of two separate units. Served after one fresh air, through another, the contaminated one is removed.

Air conditioning is ventilation unit, which, using automatic control devices, maintains the specified air parameters in the room.

There are two types of air conditioners: full air conditioning units, which ensure constancy of temperature, relative humidity, air speed and air purity, as well as incomplete air conditioning units, which ensure the constancy of only part of these parameters or one parameter, most often temperature.

Depending on the method of refrigeration supply, air conditioners are divided into autonomous and non-autonomous. In stand-alone air conditioners, the cold is produced by its own built-in refrigeration units. Non-autonomous air conditioners are supplied with coolants centrally.

According to the method of preparing and distributing air, air conditioners are divided into central and local. The design of central air conditioners provides for the preparation of air outside the serviced premises and its distribution through the air duct system. In local air conditioners, air is prepared directly in the premises served; the air is distributed concentratedly, without air ducts.

Life safety Viktor Sergeevich Alekseev

25. Industrial ventilation and conditioning

Ventilation– indoor air exchange carried out using various systems and devices.

As a person stays indoors, the air quality in the room deteriorates. Along with exhaled carbon dioxide Other metabolic products, dust, and harmful industrial substances also accumulate in the air. In addition, the temperature and humidity rise. Therefore, there is a need for room ventilation, which ensures air exchange– removing polluted air and replacing it with clean air.

Air exchange can be carried out naturally - through vents and transoms.

The best method of air exchange is artificial ventilation, in which fresh air is supplied and polluted air is removed mechanically - using fans and other devices.

Most perfect form artificial ventilation is air conditioning- creation and maintenance of indoors and transport using technical means the most favorable (comfortable) conditions for people, to ensure technological processes, operation of equipment and devices, preservation of cultural and artistic values.

Air conditioning is achieved by creating optimal parameters of the air environment, its temperature, relative humidity, gas composition, air speed and air pressure.

Air conditioning units are equipped with devices for cleaning air from dust, for heating, cooling, drying and humidifying it, as well as for automatic regulation, control and management. In some cases, using air conditioning systems, it is also possible to carry out odorization (saturation of air with aromatic substances), deodorization (neutralization unpleasant odors), regulation of ionic composition (ionization), removal of excess carbon dioxide, oxygen enrichment and bacteriological air purification (in medical institutions where patients with airborne infection are located).

Distinguish central systems air conditioning systems, which usually serve the entire building, and local ones, which serve one room.

Air conditioning is carried out using air conditioners various types, the design and arrangement of which depend on their purpose. Various devices are used for air conditioning: fans, humidifiers, air ionizers. In the premises, the optimal air temperature in winter is from + 19 to +21 C, in summer – from +22 to +25 C with a relative air humidity of 60 to 40% and an air speed of no more than 30 cm/s.

55. Artificial ventilation Artificial ventilation (ALV) provides gas exchange between the surrounding air (or a certain mixture of gases) and the alveoli of the lungs, is used as a means of resuscitation in case of sudden cessation of breathing, as a component