Ventilation and heating of industrial premises. Occupational Safety and Health

OCCUPATIONAL SAFETY AND HEALTH
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Ventilation and heating of industrial premises. Occupational Safety and Health

Occupational Safety and Health

Occupational Safety and Health / Legislative basis for labor protection

ventilation is a complex of interrelated devices and processes to create the required air exchange in industrial premises. The main purpose of ventilation is to remove polluted or overheated air from the working area and supply clean air, as a result of which the necessary favorable air conditions are created in the working area. One of the main tasks that arise in the ventilation device is the determination of air exchange, i.e., the amount of ventilation air necessary to ensure the optimal sanitary and hygienic level of indoor air.

Depending on the method of air movement in industrial premises, ventilation is divided into natural and artificial (mechanical). Their combination is also possible - mixed ventilation.

If there are no harmful emissions in the room, then ventilation should provide air exchange of at least 30 m3 / h for each worker (for rooms with a volume of up to 20 m3 per worker). When harmful substances are released into the air of the working area, the necessary air exchange is determined based on the conditions for their dilution to the MPC, and in the presence of thermal excesses, from the conditions for maintaining an acceptable temperature in the working area.

Natural ventilation industrial premises is carried out due to the temperature difference in the room of the outside air (thermal pressure) or the action of the wind (wind pressure). Natural ventilation can be organized and unorganized.

RџSЂRё unorganized natural ventilation air exchange is carried out by displacing internal thermal air with external cold air through windows, vents, transoms and doors.

Organized natural ventilation (or aeration) provides air exchange in pre-calculated volumes, regulated in accordance with meteorological conditions.

Channelless aeration It is carried out with the help of openings in the walls and ceiling and is recommended in large rooms with significant excess heat. To obtain the calculated air exchange, ventilation openings in the walls, as well as in the roof of the building (aeration lights) are equipped with transoms that open and close from the floor of the room. By manipulating the transoms, it is possible to regulate the air exchange when the outside air temperature or wind speed changes (Fig. 3).

Ventilation and heating of industrial premises
Fig.3. Natural ventilation of the building a - when there is no wind; b - in the wind; 1 - exhaust and supply openings; 2 - heat generating unit

In industrial premises of a small volume, as well as in premises located in multi-storey industrial buildings, apply channel aeration, in which polluted air is removed through ventilation ducts in the walls. To enhance the exhaust at the outlet of the channels on the roof of the building, install deflectors - devices that create traction when blown by the wind.

Natural ventilation is cheap and easy to operate. Its main disadvantage is that the supply air is introduced into the room without prior cleaning and heating, and the exhaust air is not cleaned and pollutes the atmosphere. Natural ventilation is applicable where there are no large emissions of harmful substances into the air of the working area.

Artificial (mechanical) ventilation eliminates the disadvantages of natural ventilation. With mechanical ventilation, air exchange is carried out due to the air pressure created by fans (axial and centrifugal); the air is heated in winter, cooled in summer and, in addition, cleaned of contaminants (dust, harmful vapors and gases). Mechanical ventilation can be supply, exhaust, supply and exhaust, and at the place of action - general and local.

RџSЂRё supply ventilation system air is taken from the outside with the help of a fan through a heater, where the air is heated and, if necessary, humidified, and then fed into the room. The amount of air supplied is regulated by valves or dampers installed in the branches. Polluted air exits through doors, windows, lanterns and crevices uncleaned.

RџSЂRё exhaust ventilation system polluted and superheated air is removed from the room through a network of air ducts using a fan. Polluted air is cleaned before being released into the atmosphere. Clean air is sucked in through windows, doors, leaky structures.

Supply and exhaust ventilation system consists of two separate systems - supply and exhaust, which simultaneously supply clean air to the room and remove polluted air from it. Supply ventilation systems also compensate for the air removed by local exhausts and used for technological needs: fire processes, compressor units, pneumatic transport, etc.

RџSЂRё general ventilation, used in all classrooms, emitting harmful substances are diluted with supplied clean air to the MPC.

Local ventilation there is an extract and a supply. Exhaust ventilation is arranged when pollution can be captured directly at the place of their occurrence. To do this, use fume hoods, umbrellas, curtains, on-board suction from baths, casings, exhaust from machine tools, etc. Supply ventilation includes air showers, curtains, oases.

Fume hoods work with natural or mechanical exhaust. To remove excess heat or harmful impurities from the cabinet in a natural way, it is necessary to have a lifting force that occurs when the air temperature in the cabinet exceeds the air temperature in the room. The removed air must have sufficient energy to overcome the aerodynamic resistance on the way from the entrance to the cabinet to the point of release into the atmosphere.

Heating systems are central and local. In systems central heating energy is generated outside the heated premises, and then distributed through a pipe system to consumers. Central heating, depending on the type of coolant, is water, air, steam. In small schools (with the number of students up to 500 and area up to 1000 m2), it is possible to use local heating systems, the basis of which is the combination of an energy generator with a heating device.

Currently, gas or electric is used as local heating. Heaters are installed in heated rooms for heating. The type of device depends on the heating system: for air heating, these are heaters, in water heating systems, radiators, convectors, smooth and ribbed pipes. In radiant and surface heating systems, the functions of the heaters are carried out by walls, ceilings, etc. Heaters with a heat carrier temperature above 100 ° C must be protected to prevent burns to people if accidentally touched. In air heating systems, the air heated in the heaters is supplied to the heated room. In industrial buildings, air heating uses recirculated air, and in most cases outside air. In school workshops, it is allowed to combine air heating with supply ventilation at a supply air temperature of not more than 60 ° C.

Currently, air conditioning is increasingly being used to maintain comfortable conditions in the area where people stay.

Air conditioning system called a set of technical means used for the preparation, movement and distribution of air, as well as for the automatic control of its parameters. Air conditioning systems include means for dust removal, for heating, cooling and humidifying air, automatic regulation of its parameters, control and management.

Authors: Volkhin S.N., Petrova S.P., Petrov V.P.

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