Industrial ventilation and air conditioning. Improving the air environment. Ventilation systems Basics of organizing the construction of ventilation and air conditioning systems for buildings for various purposes

An effective remedy Ventilation ensures proper cleanliness and acceptable parameters of indoor air microclimate. Ventilation called organized and regulated air exchange, ensuring the removal of polluted air from the room and the supply of fresh air in its place.

According to the method of air movement, systems are distinguished between natural and mechanical ventilation. A ventilation system in which the movement of air masses is carried out due to the resulting pressure difference outside and inside the building is called natural ventilation.

Unorganized natural ventilation - infiltration, or natural ventilation, carried out by changing the air in the premises through leaks in fences and elements building structures due to the difference in pressure outside and inside the room. Such air exchange depends on random factors: wind strength and direction, air temperature inside and outside the building, type of fencing and quality construction work. 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 hours.

For constant air exchange required by the conditions for maintaining clean air in the room, it is necessary organized ventilation(aeration).

Aeration called organized natural general ventilation of premises as a result of the entry and removal of air through opening transoms of windows and lanterns. Air exchange in the room is regulated by varying degrees of opening of the transoms depending on the outside temperature, wind speed and direction. As a method of ventilation, aeration has found wide application in industrial buildings, characterized by technological processes with high heat generation (rolling, foundry, forging shops).

The main advantage of aeration is the ability to carry out large air exchanges at no cost mechanical energy. The disadvantages of aeration include the fact 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 the fact that the air entering the room is not cleaned or cooled.

Ventilation, by which air moves through duct systems using stimulants, is called mechanical ventilation.

Mechanical ventilation has a number of advantages over natural ventilation: a 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; the ability to subject the air introduced into the room to pre-cleaning or humidification, heating or cooling; the ability to organize optimal air distribution with air supply directly to workplaces; the ability to 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. The disadvantages of mechanical ventilation include the significant cost of construction and its operation and the need to take measures to combat noise.

Mechanical ventilation systems are divided into public, local, mixed, emergency and 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. Typically, the volume of air £pr supplied to the room at general ventilation, is equal to the volume of air £в removed from the room. However, in a number of cases it becomes necessary to violate this equality (Fig. 4.1). So, in especially clean industries, for which great importance has no dust, the volume of air inflow is greater than the volume of the exhaust, due to which some excess pressure is created R in the production area, which prevents dust from entering from adjacent rooms. In general, the difference between the volumes of supply and exhaust air should not exceed 10-15%.

Rice. 4.1.

Air circulation in the room and, accordingly, the concentration of impurities and the distribution of microclimate parameters depend not only on the presence of supply and exhaust jets, but also on their relative position. There are four main schemes for organizing air exchange during general ventilation: from top to bottom (Fig. 4.2, i), from top to top (Fig. 4.2, b); from bottom to top (Fig. 4.2, V); from bottom to bottom (Fig. 4.2, G). In addition to these schemes, combined ones are used. The most uniform air distribution is achieved when the inflow is uniform across the width of the room and the exhaust is concentrated.

When organizing air exchange in rooms, it is necessary to take into account physical properties harmful vapors and gases, and primarily their density. If the gas density is lower than the air density, then the contaminated air is removed in the upper zone, and fresh air is supplied directly to the working area. When gases with a density greater than the density of air are released, 60-70% of contaminated air is removed from the lower part of the room and 30-40% from the upper part. In rooms with significant emissions

Rice. 4.2.

moisture extractor humid air is carried out in the upper zone, and fresh food is supplied in an amount of 60% to the working zone and 40% to the upper zone.

Based on the method of supplying and removing air, there are four general ventilation schemes (Fig. 4.3): supply, exhaust, supply and exhaust, and with a recirculation system.

By 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.

Settings supply ventilation(Fig. 4.3, A) usually composed of the following elements: air intake device / for intake clean air; 2 air ducts through which air is supplied to the room, filters 3 for cleaning air from dust, air heaters 4, in which the cold is heated outside air; motion stimulator 5, humidifier-dryer 6, supply openings or nozzles 7 through which air is distributed throughout the room.

Rice. 4.3.

A - supply ventilation (PV); b - exhaust ventilation (VV); V - supply and exhaust ventilation with recirculation

Air is removed from the room through leaks in the enclosing structures.

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. It is advisable to use an exhaust system if the harmful emissions of a given room should not spread to neighboring ones, for example, for hazardous workshops and chemical laboratories.

Settings exhaust ventilation(Fig. 4.3, b) consist of exhaust openings or nozzles 8, through which air is removed from the room; motion stimulator 5, air ducts 2; devices for air purification from dust or gases 9, installed to protect the atmosphere, and air release devices 10, which is located 1 - 1.5 m above the roof ridge. Clean air enters the production premises through leaks in the enclosing structures, which is a disadvantage of this ventilation system, since an unorganized influx of cold air (drafts) can cause colds.

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

In some cases, to reduce air heating costs, they use ventilation systems with partial recirculation (Fig. 4.3, V). In them, air sucked from room II by the exhaust system is mixed with the air coming from outside. The amount of fresh and secondary air is controlled by valves 11 n 12. Fresh air in such systems usually accounts for 20-10% of the total amount of supplied air. A ventilation system with recirculation is allowed to be used only for those rooms in which there are no emissions of harmful substances or the emitted substances belong to the 4th hazard class (see paragraph 3.2 of Table 3.4) and their concentration in the air supplied to the room does not exceed 30% maximum permissible concentration (MPC) - The use of recirculation is not allowed if the air in the premises contains pathogenic bacteria, viruses or there are pronounced unpleasant odors.

Individual installations of general mechanical ventilation may not include all of the above elements. For example, supply systems are not always equipped with filters and devices for changing air humidity, and sometimes supply and exhaust systems may not have a network of air ducts.

The calculation of the required air exchange during general ventilation is made based on production conditions and the presence of excess heat, moisture and harmful substances. To qualitatively assess the efficiency of air exchange, the concept of air exchange rate is used Ka - the ratio of the amount of air entering the room per unit time b (m3/h), to the volume of the ventilated room V, (m3). With properly organized ventilation, the air exchange rate should be significantly greater than one.

In a normal microclimate and the absence of harmful emissions, the amount of air for general ventilation is used depending on the volume of the room per worker. The absence of harmful secretions is the amount of them in technological equipment, with the simultaneous release of which in the air of the room the concentration of harmful substances will not exceed the maximum permissible. In industrial premises with a volume of air for each worker Un1< 20 м3 расход воздуха на одного работающего bx must be at least 30 m3/h. In a room with Ki1 = 20-40 m3I, > 20 m2/h. In rooms with UpH > 40 m3 and in the presence of natural ventilation, air exchange is not calculated. In the absence of natural ventilation (sealed cabins), the air flow per worker must be at least 60 m3/h. Necessary air exchange for everything production premises overall equal

Where P - the number of workers in this room.

When determining the required air exchange to combat excess heat, a balance of sensible heat of the room is drawn up, based on which the volume of air for excess heat is calculated D<2из6:

where rdr is the density of the supply air, kg/m; £ух, £р - temperature of outgoing and supply air, °С; ср - specific heat capacity, kJ/kg-m3;

where bvr is the intensity of formation of harmful substances, mg/h; StsdK, S"r - concentrations of harmful substances within the maximum permissible concentration and in the supply air.

The concentration of harmful substances in the supply air should be as minimal as possible and not exceed 30% of the maximum permissible concentration.

Required air exchange for removal excess moisture determined based on the material balance of moisture and in the absence of local suction in the production area according to the formula

where (gvp is the amount of water vapor released into the room, g/h; p"p is the density of the air entering the room, kg/m; yuh is the permissible content of water vapor in the air of the room at standard temperature and relative humidity air, g/kg; s!pr - moisture content of supply air, g/kg.

When harmful substances that do not have a unidirectional effect on the human body, for example, heat and moisture, are simultaneously released into the work area, the necessary air exchange is assessed by the largest amount of air obtained in calculations for each type of emissions produced.

When several harmful substances of unidirectional action are simultaneously released into the air of the working area (sulfur and sulfur dioxide; nitrogen oxides together with carbon monoxide, etc., see CH 245-71), the calculation of general ventilation should be made by summing the volumes of air required to dilute each substance separately up to its conditional maximum permissible concentrations (C), taking into account air pollution by other substances. These concentrations are less than the standard SPdK and are determined from the equation U "" < 1.

By using local ventilation the necessary meteorological parameters are created at individual workplaces. For example, capturing harmful substances directly at the source, ventilation of observation booths, etc. Local exhaust ventilation is the most widely used. The main method of combating harmful secretions is to design and organize suction from shelters.

The designs of local suction can be completely closed, semi-open or open (Fig. 4.4). Closed suctions are the most effective. These include casings and chambers that hermetically or tightly cover technological equipment (Fig. 4.4, A). If it is impossible to arrange such shelters, then exhaust systems with partial shelter or open ones are used: exhaust zones, suction panels, fume hoods, side exhausts, etc.

One of the simplest types of local suction is an exhaust hood (Fig. 4.4, and). It serves to trap harmful substances that have a lower density than the surrounding air. Umbrellas are installed above baths for various purposes, electric and induction furnaces, and above openings for releasing metal and slag from cupola furnaces. Umbrellas are made open on all sides and partially open on one, two and three sides. The efficiency of an exhaust hood depends on the size, height of the suspension and its opening angle. The larger the size and the lower the umbrella is installed above the place where substances are released, the more effective it is. The most uniform suction is ensured when the umbrella opening angle is at least 60°.

Suction panels (Fig. 4.4, V) used to remove secretions carried away by convective currents during manual operations such as electric welding, soldering, gas welding, metal cutting, etc. Fume hoods (Fig. 4.4, e) - the most effective device compared to other suction systems, since it almost completely covers the source of the release of harmful substances. Only the service openings remain uncovered in the cabinets, through which air from the room enters the cabinet. The shape of the opening is chosen depending on the nature of the technological operations.

The required air exchange in local exhaust ventilation devices is calculated based on the localization conditions of impurities released from the source of formation. The required hourly volume of sucked air is determined as the product of the area of ​​the suction intake openings P (m2) and the air speed in them. Air speed in the suction opening

Rice. 4.4.

A - shelter box; b - onboard suctions (1 - single-sided, 2 - double-sided); V - side blowjobs (1 - unilateral, 2 - angular); G - suction from work tables; d - stained glass type suction;

e - fume hoods (1st upper suction, 2nd bottom suction, 3 - with combined suction); and - exhaust hoods (1 - straight, 2 - inclined)

V (m/s) depends on the hazard class of the substance and the type of local ventilation air intake (g) = 0.5^-5 m/s).

Mixed ventilation system is a combination of elements of local and general ventilation. The local system removes harmful substances from machine covers and covers. 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 release of a large amount of harmful or explosive substances into the air is possible. The performance of emergency ventilation is determined in accordance with the requirements of regulatory documents in the technological part of the project. If such documents are missing, then the performance of emergency ventilation is accepted such that it, together with the main ventilation, is turned on automatically when the maximum permissible concentration of harmful emissions is reached or when one of the general or local ventilation systems is stopped. The release of air from emergency systems must be carried out taking into account the possibility of maximum dispersion of harmful and explosive substances in the atmosphere.

To create optimal meteorological conditions in industrial premises, the most advanced type of industrial ventilation is used - air conditioning. Air conditioning is its automatic processing in order to maintain predetermined meteorological conditions in industrial 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 air. technological process in room. Such strictly defined air parameters are created in special installations called air conditioners. In some cases, in addition to ensuring sanitary standards for the air microclimate, air conditioners undergo special treatment: ionization, deodorization, ozonation, etc.

Air conditioners can be local (for maintenance separate rooms) and central (for servicing several separate rooms). The circuit diagram of the air conditioner is shown in Fig. 4.5.

The outside air is cleaned of dust in the filter 2 and enters chamber I, where it is mixed with air from the room (during recirculation). Having passed through the stage of preliminary temperature treatment 4, the air enters chamber II, where it undergoes special treatment (air washing with water, ensuring the specified parameters of relative humidity, and air purification), and into chamber III (temperature treatment). During temperature treatment in winter, the air is heated partly due to the temperature of the water entering the nozzles 5, and partially, passing through heaters 4 And 7. In summer, the air is cooled partially by the supply of chilled (artesian) water to chamber II and, mainly, as a result of the operation of special refrigeration machines.

Air conditioning plays a significant role not only from the point of view of life safety, but is also necessary in many high-tech industries, so in recent years it has been increasingly used in industrial enterprises. The adverse effects of excess or lack of heat can be significantly reduced or eliminated by improving technical processes, using automation and mechanization, as well as using a number of sanitary, technical and organizational measures: localization of heat generation, thermal insulation of heating surfaces, shielding, air and water-air showering, air oases, air curtains, rational work and rest regime.

In any case, measures must ensure irradiation in workplaces of no more than 350 W/m2 and equipment surface temperature of no higher than 308 K (35 °C) at a temperature inside the source of up to 373 K (100 °C) and not higher than 318 K (45 °C ) at temperatures inside the source above 373 K (100 °C).

Rice. 4.5.

1 - intake duct; 2 - filter; 3 - connecting duct; 4 - heater; 5 - air humidifier nozzles; 6 - drip eliminator; 7 - second stage heater; 8 - fan; 9 - exhaust duct

For non-fixed workplaces and outdoor work in cold climates, special rooms for heating are organized. Under unfavorable meteorological conditions (air temperature -10 °C and below), heating breaks of 10-15 minutes every hour are required.

At outdoor temperatures (-30) - (-45) °C, 15-minute rest breaks are organized every 60 minutes from the start of the work shift and after lunch, and then every 45 minutes of work. It is necessary to provide the possibility of drinking hot tea in heating rooms.

An effective means of ensuring proper cleanliness and acceptable microclimate parameters of the air in the working area is industrial ventilation.

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 - is carried out by changing the air in the premises through leaks in fences and elements of 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).

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

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

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 does not enter the work area. To do this, outside air is supplied 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 into the room by a supply system and removed by an exhaust system.

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.

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 simplest types of local suction is a fume 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. The local system removes harmful substances from machine covers and covers. 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 of a large amount of harmful or explosive substances is possible.

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 ensuring sanitary standards for the air microclimate, air conditioners undergo 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 air temperature and humidity are not allowed (especially in radio electronics). Therefore, air conditioning units have been increasingly used in industrial enterprises in recent years.

Under normal conditions, a person emits about 18 liters of carbon dioxide per hour. Excess, as well as deficiency, of carbon dioxide has a harmful effect on the human condition. The permissible values ​​of carbon dioxide concentration in the room are: 0.03-0.07% - for the stay of children and patients; 0.07-0.1% – for long-term stay of people.

When designing ventilation and air conditioning systems, technical solutions are provided that ensure the normalized parameters listed above air environment. Specific requirements for the air environment for objects for various purposes are set out in building codes and regulations. The list of basic standards in the field of ventilation and air conditioning in force in Ukraine is given in Appendix 1.

1.2. Classification of ventilation systems.

There is no standard classification of SLE, but in practice and in the technical literature certain terminology and classification have developed, which we will adhere to.

Depending on the method of causing air movement, ventilation systems are divided into natural (gravitational) and artificial (with mechanical propulsion).

By purpose - for supply, exhaust and mixed.

By service area - general exchange and local.

By design– for ducted and ductless.

Air exchange during natural ventilation (aeration) occurs due to the difference in densities of indoor and outdoor air or the difference in temperatures between atmospheric air and indoor air.

In rooms with large heat releases, the air is always warmer than the outside air. Heavier outside air, entering the room, displaces less dense air from it. As a result, air circulation occurs in the room, similar to that artificially created by a fan.

On systems with natural ventilation , in which air movement is created due to the difference in pressure of the air column, the minimum height difference between the level of air intake from the room and its release through the deflector must be at least 3 m. In this case, the recommended length of horizontal sections should not exceed 3 m, and the air speed in air ducts – 1 m/s.

Aeration is used in workshops if the concentration of dust and harmful gases in the supply air does not exceed 30% of the maximum permissible in work area. If pre-treatment of the supply air is required, aeration is not used.

Sometimes a phenomenon is used to organize air flow in a room wind pressure , which consists in the fact that an increased pressure is formed on the side of the building facing the wind, and a vacuum is formed on the opposite side.

Natural ventilation systems are simple and do not require complex expensive equipment or operating costs. However, the dependence of the effectiveness of these systems on external factors (outside air temperature, wind direction and speed), as well as low pressure, does not allow them to solve all complex and diverse problems in the field of ventilation. Therefore, systems with mechanical impulse.

Mechanically driven systems use equipment (fans) to move air to desired distances. If necessary, the air is subjected to various types of processing: cleaning, heating, cooling, humidification, drying. Mechanically driven ventilation can be divided into local And general exchange.

Local ventilation is called one that provides air supply to certain places (local supply ventilation) and polluted air is removed only from places where harmful emissions are formed (local exhaust ventilation).

Local ventilation provides air exchange only in the working area, and general exchange- throughout the room.

Local ventilation includes air showers (concentrated air flow at increased speed). They must supply clean air to permanent work areas, reduce the air temperature in their area and provide ventilation to workers exposed to heat.

TO local supply ventilation include air oases - areas of premises fenced off from the rest of the room by partitions 2-2.5 m high, into which air with a low temperature is pumped. Local supply ventilation is also used in the form of air curtains (at gates, entrances, stoves, etc.), which create air partitions or change the direction of air flows. Local ventilation requires less cost than general exchange. In industrial premises, in the presence of harmful emissions (gases, moisture, heat, etc.), a mixed ventilation system is usually used: general - to eliminate harmful emissions throughout the entire volume of the room and local (local suction and inflow) - to service workplaces.

Local exhaust ventilation is used when the places of harmful emissions in the room are localized and their spread throughout the room cannot be allowed. Local exhaust ventilation in industrial premises ensures the capture and removal of harmful emissions: gases, smoke, dust and heat. To remove harmful secretions, local suctions are used (shelters in the form of cabinets, umbrellas, boat suctions, etc.).

Harmful emissions must be removed from the place of formation in the direction of their natural movement: hot gases and vapors should be removed upward, and cold heavy gases and dust - downward. When installing local exhaust ventilation to capture dust emissions, the air removed from the room must be cleaned using filters before being released into the atmosphere. If local ventilation cannot meet sanitary, hygienic or technological requirements, use general ventilation systems .

General exhaust systems remove air evenly from the entire room, and general exchange inlet – supply air and distribute it throughout the entire volume of the ventilated room. When supply and exhaust ventilation operate simultaneously, they must be balanced in terms of air flow.

If the air supplied to a room is formed by mixing outside air and air taken from the room, then such a system is called supply and recirculation .

Ventilation systems that supply and remove air through channels or ducts are called duct , and those without channels – ductless .

A system designed to remove dust generated during technological processes is called aspiration .

Aspiration systems are divided into:

individual, when each workplace has a separate exhaust unit;

central , when one installation serves a group of workstations.

To move lightweight materials (wood shavings, textile waste, cotton, etc.), ventilation systems called by pneumatic transport.

1.2.1. Natural ventilation

Air exchange in industrial premises is carried out using natural ventilation or mechanical ventilation units.

Organized air exchange during natural ventilation (aeration) is ensured due to the difference in temperature (density) of the air, as well as as a result of wind pressure.

Under the influence of heat generated by machines and mechanisms, heated coal (during drying), people, as well as heated surfaces, the air temperature in production areas increases and becomes higher than the outside air temperature.

The heated air in production premises rises upward and goes outside through openings in the ceilings (roof).

Cold outside air enters the room through open openings in the lower or middle zones. As a result, natural air exchange is created, called thermal pressure.

The value of thermal pressure is determined by the formula

N m = h (ρ n – ρ V) g, N/m 2 , (1)

Where h – height between the centers of exhaust and supply openings, m; ρ n and ρ c – density of external and internal air, kg/m3; g– free fall acceleration equal to 9.81 m/s 2 .

Natural ventilation can be unorganized and organized. With unorganized ventilation, unknown volumes of air enter and are removed from the room, and the air exchange itself depends on random factors (direction and strength of the wind, temperature of external and internal air). Unorganized natural ventilation includes infiltration – air leakage through leaks in windows, doors, ceilings and ventilation, which occurs when windows and vents are opened.

Organized natural ventilation is called aeration. For aeration, holes are made in the walls of the building to allow in external air, and special devices (lanterns) are installed on the roof or in the upper part of the building to remove exhaust air. To regulate the supply and removal of air, the aeration holes and skylights are covered by the required amount. This is especially important during the cold season.

1.2.2. Artificial ventilation.

Artificial (mechanical) ventilation, in contrast to natural ventilation, makes it possible to purify the air before releasing it into the atmosphere, trap harmful substances directly near the places of their formation, process the inflowing air (clean, heat, humidify), and more specifically supply air to the work area. In addition, mechanical ventilation makes it possible to organize air intake in the cleanest area of ​​the enterprise territory and even beyond it.

General exchange artificial ventilation.

General exchange ventilation ensures the creation of the necessary microclimate and clean air throughout the entire volume of the workroom. It is used to remove excess heat in the absence of toxic emissions, as well as in cases where the nature of the technological process and the features of production equipment exclude the possibility of using local exhaust ventilation.

There are four main schemes for organizing air exchange during general ventilation: top-down, top-up, bottom-up, bottom-down (Fig. 1).

Rice. 1 – Scheme of organizing air exchange during general ventilation

Schemes from top to bottom (Fig. 1a) and from top to top (Fig. 16 ) is advisable to use if the supply air during the cold season has a temperature lower than the room temperature. The supply air, before reaching the work area, is heated by the air in the room. The other two schemes (Fig. 1c And 1g) is recommended for use in cases where the supply air heats up during the cold season and its temperature is higher than the temperature of the internal air in the room.

If gases and vapors are emitted in industrial premises with a density that exceeds the density of air (for example, vapors of acids, gasoline, kerosene), then general ventilation should provide up to 60% of the air from the lower zone of the room and 40% – from the top.

If the density of gases is less than the density of air, then the removal of contaminated air is carried out in the upper zone.

Forced ventilation. The scheme of supply mechanical ventilation (Fig. 2.) includes: air collector 1; air purification filter 2; air heater (heater) 3; fan 5; a network of air ducts 4 and supply pipes with nozzles 6. If there is no need to heat the supply air, then it is passed directly into the production premises through the bypass channel 7.

Rice. 2 – Supply ventilation diagram

Air intake devices must be located in places where the air is not polluted by dust and gases. They must be located at least 2 m from the ground level, and from the exhaust ventilation exhaust ducts vertically – below 6 m and horizontally – no more than 25 m.

Supply air is supplied to the premises, as a rule, in a dispersed flow, for which special nozzles are used.

Exhaust and supply and exhaust ventilation. Exhaust ventilation (Fig. 3) consists of a cleaning device 1, fan 2, central 3 and suction air ducts 4.

Rice. 3 – Exhaust ventilation diagram

Air after purification must be exhausted at a height of at least 1 m above the roof ridge. It is prohibited to make discharge holes directly in the windows.

In industrial production conditions, the most common is a supply and exhaust ventilation system with a general air flow into the work area and local exhaust of harmful substances directly from the places of formation.

In industrial premises where a significant amount of harmful gases, vapors and dust are emitted, the exhaust should be 10% more than the inflow, so that harmful substances are not displaced into adjacent rooms with less harmfulness.

In the supply and exhaust ventilation system, it is possible to use not only external air, but also the air of the premises itself after it has been purified. This reuse of indoor air is called recycling and is carried out during the cold season to save heat spent on heating the supply air. However, the possibility of recycling is determined by a number of sanitary, hygienic and fire safety requirements.

Local ventilation.

Local ventilation can be supply And exhaust.

Local supply ventilation , in which a concentrated presentation of supply air of specified parameters (temperature, humidity, speed of movement) is carried out, performed in the form of air showers, air and air-thermal curtains.

Air showers are used to prevent overheating of workers in hot shops, as well as to form so-called air oases (areas of the production zone that differ sharply in their physical and chemical characteristics from other premises).

Air and air-heat curtains are designed to prevent the entry of significant masses of cold outside air into the premises and the need for frequent opening of doors or gates. The air curtain is generated by a stream of air, which is supplied from a narrow long slit, D at a certain angle towards the flow of cold air. A channel with a slot is placed on the side or on top of the gate (door).

Local exhaust ventilation carried out using local exhaust hoods, suction panels, fume hoods, and on-board pumps (Fig. 4).

Rice. 2.5 - Examples of local exhaust ventilation:

A – exhaust hood, b – suction panel, V – fume hood with combined hood, G – onboard pump with blower.

The design of local exhaust ventilation should ensure maximum capture of harmful substances with a minimum amount of removed air. In addition, it should not be bulky and interfere with the maintenance personnel’s work and supervision of the technological process.

The main factors when choosing the type of local exhaust ventilation are the characteristics of harmful factors (temperature, density of gases and vapors, toxicity), the position of the worker when performing work, features of the technological process and equipment.

In cases where the source of production premises can be placed inside a spacious space limited by walls, local exhaust ventilation is arranged in the form of fume hoods, casings, and wind pumps. If, due to technology or service conditions, the source of the incident cannot be isolated, then an exhaust hood or suction panel is installed. In this case, the air flow that is removed should not pass through the worker’s breathing zone

A special case of local exhaust ventilation are on-board pumps that are used to equip baths (plating, pickling) or other containers with toxic liquids, since the need to use lifting and transport equipment when loading them makes it impossible to use exhaust hoods and suction panels. If the bathtub width is 1 m or more, it is necessary to install an on-board pump with blowing (Fig. 2.6d), in which air is sucked out on one side of the bathtub, and on the other – is being pumped up. In this case, the moving air seems to screen the surface of the evaporation of toxic liquid substances.

2.3. Basic requirements for ventilation systems.

Natural and artificial ventilation must meet the following sanitary and hygienic requirements:

– create normal climatic working conditions in the working area of ​​the premises (temperature, humidity and air speed);

– completely eliminate harmful gases, vapors, dust and aerosols from the premises or dilute them to maximum permissible concentrations;

– prevent the entry of polluted air into the premises from the outside or through the influx of polluted air from adjacent premises;

– do not create drafts or sudden cooling of air in the workplace;

– be available for management and repair during operation;

– do not create additional inconveniences during operation (for example, noise, vibrations, rain, snow).

Most fully meets the above requirements air conditioning system air, which is also widely used in enterprises. By using air conditioners the specified air parameters are created and automatically maintained in the production area. When deciding whether to use air conditioning, economic factors should also be taken into account.

It should be noted that a number of additional requirements are put forward for ventilation systems installed in fire and explosion hazardous areas, which are not discussed in this section.

1.3. Classification of air conditioning systems.

Air conditioning systems can be classified as follows:

1. According to the degree of ensuring meteorological conditions in the serviced premises, air conditioning systems are divided into three classes: first, second And third.

2. According to the pressure developed by the fans, – low (up to 1000 Pa), average (up to 3000 Pa) and high (over 3000 Pa) pressure.

3. According to the intended purpose of the object of use - comfortable And technological.

4. By the presence of sources of heat and cold - autonomous And non-autonomous.

5. According to the principle of location of the air conditioning system relative to the serviced object - central And local.

6. By the number of premises served – single-zone And multi-zone.

7. By type of objects served – household , semi-industrial And industrial .

Air conditioning systems first class provide the parameters required for the technological process in accordance with regulatory documents.

Systems second class provide sanitary and hygienic standards or required technological standards.

Systems third class provide acceptable standards if they cannot be provided with ventilation in the warm season without the use of artificial air cooling.

Optimal parameters air represent a set of conditions that are most favorable for the well-being of people (the area of ​​comfortable air conditioning), or conditions for the correct flow of the technological process (the area of ​​technological air conditioning). The optimal parameters of internal air in industrial enterprises are established based on the position that if the quantity and quality of products depends on compliance with the exact regime of the technological process, and not on the intensity of labor, then the determining factor is the requirements of the technological process. If the output of products is mainly influenced by the intensity labor, comfortable conditions are established for people working in the workshop.

Valid parameters air are installed in cases where, due to technological requirements or technical and economic reasons, optimal standards are not provided ( SNiP 2.04.05-91).

Autonomous SCR They include a full range of equipment that allows for the necessary air treatment in accordance with regulatory requirements for cleaning, heating, cooling, drying, humidification, movement and distribution of air, as well as means of automatic and remote control and monitoring. To operate an autonomous SCR, only electrical energy must be supplied. Autonomous air conditioners include monoblock window, cabinet air conditioners, and split systems.

Non-autonomous hard currency do not have built-in units that are sources of heat and cold. These SCRs are supplied with cold or hot refrigerants (water, freons) from other sources of heat and cold supply.

Central hard currency They are non-autonomous air conditioners located outside the serviced premises, in which air is prepared and then distributed throughout the premises using air ducts. Modern central air conditioners are produced in sectional versions from unified standard models.

Local hard currency are produced on the basis of autonomous and non-autonomous air conditioners and are installed in the serviced premises.

Single-zone SCV are used to serve one room with a uniform distribution of heat and moisture, for example, exhibition halls, cinemas, etc.

Multi-zone SCR are used to service several rooms or rooms with uneven distribution of heat and moisture.

Household air conditioners Designed for installation in residential buildings, offices and similar facilities. A feature of household air conditioners is that they are powered from a single-phase network and have a power consumption of no more than 3 kW. This is the power that standard electrical outlets installed in residential and administrative premises are allowed to consume. As a consequence of this. The cooling and heating capacity of domestic air conditioners does not exceed 7 kW.

AND conditioning air Task >> Life safety

The air microclimate of the working area is industrial ventilation. Ventilation called organized and controlled air exchange... the most advanced type is used ventilation conditioning air. Air conditioning air is called...

3. VENTILATION AND AIR CONDITIONING.

Microclimate parameters have a direct impact on a person’s thermal well-being and performance.

To maintain microclimate parameters at the level necessary to ensure comfort and vital activity, ventilation of the premises where a person carries out his activities is used. Optimal microclimate parameters are provided by air conditioning systems, and valid parameters– conventional ventilation and heating systems.

The ventilation system is a set of devices that provide air exchange in the room, i.e. removal of polluted, heated, humid air from the room and supply of fresh, clean air to the room. According to the area of ​​action, ventilation can be general exchange, in which air exchange covers the entire room, and local, when air exchange is carried out in a limited area of ​​the room. Based on the method of air movement, natural and mechanical ventilation systems are distinguished.

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

For constant air exchange required by the conditions for maintaining indoor air purity, organized ventilation, or aeration, is necessary. Aeration is the organized natural general ventilation of rooms as a result of the entry and removal of air through opening transoms of windows and doors. Air exchange in the room is regulated by varying degrees of opening of the transoms (depending on the outside temperature, wind speed and direction).

The main advantage of natural ventilation is the ability to carry out large air exchanges without the expenditure of mechanical energy. Natural ventilation, as a means of maintaining microclimate parameters and improving the indoor air environment, is used for non-industrial premises - domestic (apartments) and premises in which, as a result of human work, no harmful substances, excess moisture or heat are released.

Ventilation, by which air is supplied to or removed from rooms through systems of ventilation ducts, using special mechanical stimuli, is called mechanical ventilation. The most common ventilation system is supply and exhaust, in which air is supplied to the room by the supply system and removed by the exhaust system; systems operate simultaneously. Supply and removal ventilation systems The air is usually processed - heated or cooled, humidified or purified from contaminants. If the air is too dusty or harmful substances are released in the room, then the supply or exhaust system cleaning devices are built in.

Mechanical ventilation has a number of advantages compared to natural ventilation: a 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 distribution throughout the entire volume of the room, as well as the ability to purify polluted air before releasing it into the atmosphere. The disadvantages of mechanical ventilation include the significant cost of its construction and operation and the need to take measures to combat noise pollution.

To create optimal meteorological conditions, first of all, the most advanced type of ventilation – air conditioning – is used in industrial premises. Air conditioning is its automatic processing in order to maintain predetermined meteorological conditions in industrial 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 premises are automatically regulated depending on the time of year, external meteorological conditions and the nature of the technological process in the room. In some cases, special treatment can be carried out: ionization, deodorization, ozonation, etc. Air conditioners can be local - for servicing individual premises, rooms, and central - for servicing groups of premises, workshops and production facilities in general. Air conditioning is much more expensive than ventilation, but provides best conditions for human life and activity.

4. Heating.

The purpose of heating premises is to maintain a given air temperature in them during the cold season. Heating systems are divided into water, steam, air and combined. Water heating systems are widespread, they are efficient and convenient. In these systems, as heating devices Radiators and pipes are used. Air system cooling is that the supplied air is preheated in heaters.

The presence of a sufficient amount of oxygen in the air is a necessary condition for ensuring the vital functions of the body. A decrease in oxygen content in the air can lead to oxygen starvation - hypoxia, the main symptoms of which are headache, dizziness, slow reaction, impairment normal operation organs of hearing and vision, metabolic disorders.

5. Lighting.

A necessary condition ensuring human comfort and vital activity is good lighting.

Poor lighting is one of the reasons for increased fatigue, especially during intense visual work. Prolonged work in low light conditions leads to decreased productivity and safety. Correctly designed and rationally executed lighting of industrial, educational and residential premises has a positive psychophysiological effect on humans, reduces fatigue and injuries, and helps to increase labor efficiency and human health, especially vision.

When organizing industrial lighting, it is necessary to ensure a uniform distribution of brightness across work surface and surrounding objects. Shifting your gaze from a brightly lit to a dimly lit surface forces the eye to adapt, which leads to visual fatigue.

Due to improper lighting, deep and sharp shadows and other unfavorable factors are formed, vision quickly becomes tired, which leads to discomfort and an increase in the danger of life (primarily, an increase in industrial injuries). The presence of sharp shadows distorts the size and shape of objects and thereby increases fatigue and reduces labor productivity. Shadows must be softened, using, for example, lamps with light-diffusing milky glasses, and when natural light use sun protection devices (blinds, visors, etc.).

When lighting rooms, use natural light created by direct sun rays and diffused light of the sky and changing depending on geographical latitude, time of year and day, degree of cloudiness and transparency of the atmosphere. Natural light better than artificial, created by any light sources.

When there is insufficient illumination from natural light, artificial lighting is used, created by electrical sources light, and combined lighting, in which natural lighting, insufficient by standards, is supplemented with artificial lighting. According to its design, artificial lighting can be general or combined. With general lighting, all places in the room receive illumination from a common lighting installation. Combined lighting, along with general lighting, includes local lighting (local lamp, for example, desk lamp), focusing the light flux directly on the workplace. The use of local lighting alone is unacceptable, as there is a need for frequent readaptation of vision. A large difference in illumination in the workplace and in the rest of the room leads to rapid eye fatigue and gradual deterioration of vision. Therefore the share general lighting in the combined must be at least 10%.

The main task of industrial lighting is to maintain lighting in the workplace that matches the nature of the work. visual work. Increasing the illumination of the working surface improves the visibility of objects by increasing their brightness and increases the speed of distinguishing details.

To improve the visibility of objects in the worker’s field of vision, there should be no direct or reflected glare. Where possible, shiny surfaces should be replaced with matte ones.

Fluctuations in illumination in the workplace, caused, for example, by a sharp change in network voltage, also cause re-adaptation of the eye, leading to significant fatigue. Constancy of illumination over time is achieved by stabilizing the floating voltage, rigidly mounting lamps, and using special schemes inclusion gas discharge lamps.

Noise pollution is also a negative factor affecting humans, major cities primarily related to transport. About 40-50% of their population lives in conditions of noise pollution, which has a negative psychophysiological effect on people. Reducing noise pollution environment– an important and complex task that requires an urgent solution today.

Conclusion.

On the one hand, increasing the level of comfort in people’s lives contributes to their security. But increasing comfort is only one of the consequences of economic development, which generates a number of acute problems along the way environmental problems, which in turn lead to increased negative impacts per person. Consequently, to truly increase the level of security of people, it is necessary to ensure people’s livelihoods in accordance with the laws of nature.

Conclusion. The science of life sciences explores the world of dangers operating in the human environment, develops systems and methods for protecting people from dangers. In the modern understanding, the science of life safety studies the dangers of the industrial, domestic and urban environment, both in Everyday life, and in the event of an emergency of man-made or natural origin...

Managed and control systems, monitoring the progress of management organization, determining the effectiveness of the event, stimulating work. When choosing means of safety management, they distinguish ideological, physiological, psychological, social, educational, ergonomic, environmental, medical, technical, organizational and operational, legal and economic...

The environments turned out to be far from the acceptable requirements in terms of security. It should be noted that this is why in the last decade the doctrine of life safety in the technosphere has begun to actively develop, the main goal of which is to protect people in the technosphere from the negative impacts of anthropogenic and natural origin, achieving comfortable conditions life activity. ...

5. Rights and obligations of the employee. 6. Types of liability for misconduct and offenses in the field of labor protection. 1. The system of normative and legal acts in the field of life safety. The basis of normative and legal acts in the area of ​​safety and security is the Constitution of the Russian Federation, Labor Code RF, Code of the Russian Federation "On Administrative Offenses", Civil Code of the Russian Federation, the federal law"On the basics of labor protection in the Russian Federation", Fundamentals...

For exhaust ventilation system. In the supply ventilation system, it provides protection for workers and creates conditions for the operation of VT, and in the exhaust ventilation system, the device provides air protection populated areas from harmful influences.

Depending on the use of funds, cleaning is divided on the:

• 
  coarse (concentration of more than 100 mg/m 3 of harmful substances);
• 
  medium (concentration 100 - 1 mg/m 3 harmful substances);
• 
  thin (concentration less than 1 mg/m 3 of harmful substances).

Air purification removed from the room is carried out using 2 types of devices:

Dust collectors; - filters.

Air purification when using a dust collector is carried out due to the action of gravity and inertia forces.

By design features dust collectors are:

Cyclonic;

Inertial;

Dust settling chambers.

Filters

• 
  paper; fabric; electrical; ultrasonic; oil; hydraulic; combined

Air purification methods

1. 
   Mechanical (dust, mists, oils, gaseous impurities)
   1. 
      Dust collectors;
   2. 
      Filters
2. 
   Physico-chemical (removal of gaseous impurities)
   1. 
      Sorption
      1. 
         adsorption (activated carbon);
      2. 
         absorption (liquid)
   2. 
      Catalytic (neutralization of gaseous impurities in the presence of a catalyst)

Monitoring air parameters

• 
  Thermometer (temperature);
• 
  Psychrometer (relative humidity);
• 
  Anemometer (air speed);
• 
  Actinometer (thermal radiation intensity);

Guiding and technical principles for normalizing the air environment:

• 
  use of air conditioners.
• 
  providing more air access.
• 
  use of ventilation.

1. 
   from excessive cooling

• 
  warm clothes
• 
  local heating devices

1. 
   from thermal radiation

• 
  use of devices that eliminate the source of heat generation
• 
  use of devices protecting against thermal radiation
• 
  the use of devices that facilitate the transfer of human heat

Organizational and technical principles:

• 
  the principle of time protection – reducing to a safe value the time spent in the area of ​​exposure to harmful air factors;

• 
  the principle of compensation – compensation for damage to a person exposed to harmful factors in the air;
• 
  principle of regulation - maximum permissible concentration of harmful substances in the air of the working area;
• 
  principle rational organization labor;
• 
  the principle of evacuation - to prevent the entry of “harmful” gases and vapors into the homosphere;

Maintaining at a given level the parameters that determine the microclimate - temperature, humidity and air speed - can be done using air conditioning or, with larger tolerances, ventilation.

Air conditioning

Ventilation- organized air exchange, which ensures the removal from the room of air polluted by excess heat and harmful substances and thereby normalizes the air environment in the room.

Filters- devices in which materials (manufactured) capable of depositing or retaining dust are used to purify air.
22. Heating, ventilation and air conditioning. Classifications. Areas of use. Advantages and disadvantages.

Ventilation– this is an organized air exchange, which consists in removing polluted air from the working area and supplying fresh outside (or purified) air instead.

Ventilation can be supply or exhaust.

Exhaust ventilation is used to remove contaminated air from the room. The supply air supply serves to supply clean air into the room to replace the removed air.

Ventilation can be:

• 
  natural (air movement occurs under the influence of natural causes);
• 
  mechanical;
• 
  local;
• 
  general exchange.

Air conditioners come in full and partial air conditioning types.

Full conditioning air conditioners include ensuring constant temperature, constant relative humidity, constant air mobility and purity, ionization, ozonation, and removed odors.

Partial conditioning air conditioners support only part of the given parameters.

The use of ventilation or air conditioning depends on the location and environment of its use.
23. The main elements of the artificial general ventilation system. Methods for calculating the required air exchange for general ventilation. Air exchange rate.

Supply ventilation system

1. 
   Fence device
2. 
   Cleaning device
3. 
   Duct system
4. 
   Fan
5. 
   Feeding device for work. place

Exhaust ventilation system

1. 
   Air removal device
2. 
   Fan
3. 
   Air duct system
4. 
   Dust and gas collection devices
5. 
   Filters
6. 
   Air release device

The performance of the ventilation system is determined by the air exchange rate ( TO).

K = V/V p, where

V- amount of air removed from the room per hour [m 3 /h]

V P- volume of the room, m 3

TO=

To determine the volume of air removed from the room you need to know:

V 1 - air volume taking into account heat emissions;

V 2 - volume of air, taking into account the release of harmful substances from certain processes
25. Classification, regulation and organization of natural lighting.

In natural light, any point horizontal plane, the minimum permissible value of the natural illumination coefficient is taken as the basis for standardization.

Coef. natural lighting (KEO) = E = E VN /E CH 100%, where

E VN - illumination of any point on the horizontal surface located indoors [lx];

E CH - illumination of a point located outside the room at a distance of 1 m from the building [lx];

Natural lighting systems

1. 
   Side lighting;
2. 
   Overhead lighting;
3. 
   Combined lighting.

To select natural lighting, the following factors must be considered:

1. 
   
2. 
   Minimum size of object to distinguish from background;
3. 
   Visual work category;
4. 
   Lighting system.

26.Classification, standardization and organization artificial lighting.

Artificial lighting- lighting of premises with direct or reflected light from an artificial light source

The basis for standardization is the minimum permissible value of illumination of any point.

Artificial lighting systems

1. 
   general;
2. 
   local (local);
3. 
   combined

There is also lighting: - emergency; - duty; - evacuation.

SNiP II-4-79

Factors taken into account when rationing artificial lighting:

1. 
   Characteristics of visual work;
2. 
   Minimum size of the object to be distinguished from the background;
3. 
   Visual work category;
4. 
   Contrast of object with background;
5. 
   Background lightness (background characteristic);
6. 
   Lighting system;
7. 
   Type of light source.

Artificial lighting is used when natural light is insufficient or absent.

It is classified into working, emergency security and duty.

The following are used as light sources:

Incandescent lamps (tungsten coil is heated to melting point). Incandescent lamps can be vacuum or gas-filled.

Fluorescent lamps. They are divided into low-pressure tubular lamps and high-pressure mercury lamps.

The lamp is a glass tube sealed on both sides, inner surface which is coated with phosphor.

Lamps redistribute the luminous flux of lamps, eliminate harmful glare, and protect lamps from damage.

For incandescent lamps use:

• 
  universal direct light luminaires;

• 
  lamp for explosive areas

Dust- and water-proof lamps

Explosion-proof lamps

Open pendant diffused light

28. Methods of calculation and control of artificial lighting.

Methodology for calculating artificial lighting

1. 
   Method luminous flux
2. 
   Power density method
3. 
   Point method

Task. Determine the illumination at work. place

E RM = (0.9 - 1.2) E N

To do this you need to select:

1. 
   lighting system;
2. 
   Light source;
3. 
   lamp.

F=(ESK)/(NnZ), where

E - normalized illumination value [lx];

S - area of ​​production premises [m 2 ];

K - coefficient stock;

N - number of lamps [pcs];

Z - correction factor, depends on the type of lamp

 is the coefficient of utilization of the luminous flux, to select which you need to know:

Coef. reflections from walls and ceiling ( C,  P);

Room index - i

N R - the height of the suspension of lamps above the slave. surface;

For LL lamps, knowing the group luminous flux F and the number of lamps in the network n (2 or 4), we determine the luminous flux of one lamp.

F CALCULATION = (0.9 - 1.2) F TABLE

Distribution of luminaires across the area of ​​the production premises.

For LL - along the long side of the room, along the windows, parallel to the walls with windows.

For LN, DRL - in a checkerboard pattern.
44. Hazardous factors of laser radiation. Methods and principles of laser safety.

Laser radiation:  = 0.2 - 1000 microns.

The main source is an optical quantum generator (laser).

Features of laser radiation - monochromaticity; sharp beam direction; coherence.

Properties of laser radiation: high density energy: 10 10 -10 12 J/cm 2, high power density: 10 20 -10 22 W/cm 2.

Based on the type of radiation, laser radiation is divided into:

Direct radiation; scattered; mirror-reflected; diffuse.

By degree of danger:

1. 
   Class. First class lasers are those whose output radiation does not pose a danger to the eyes and skin.
2. 
   Class. Second class lasers include those lasers whose operation involves exposure to direct and specularly reflected radiation only on the eyes.
3. 
   Class. Lasers are characterized by the danger of exposure to the eyes of direct, specularly and diffusely reflected radiation at a distance of 10 cm from the diffusely reflective surface on the eyes, as well as direct and specularly reflected radiation on the skin.
4. 
   Class. Lasers are characterized by a risk of exposure to skin at a distance of 10 cm from a diffusely reflective surface.

• 
  ultraviolet 0.2-0.4 microns
• 
  visible 0.4-0.75 µm
• 
  infrared: near 0.75-1, far over 1.0