dwelling Ventilation
As a result of ability to live of people physical properties (the temperature and humidity raise) and a chemical compound of air of the closed premises change. In air exhaled by people quantity С0 2 increases with 0,04 to 4,4%. In badly ventilated premises there are unpleasant smells which can be result of decomposition of organic substances on a surface of a skin, linen and clothes of the person, dampness of walls, kitchen premises, lavatories etc. Even short-term stay in such atmosphere reduces working capacity, worsens the general state of health, can cause headache occurrence, a nausea, vomiting etc.
Application for the household purposes of natural or artificial gas at bad tightness of a gas network can lead to a sharp poisoning with consciousness loss, spasms and an asthma, caused by receipt in air of the closed premises of products of incomplete combustion of gas - oksidov carbon, nitrogen, formaldehyde, benzene. At combustion of 1 m 3 gas is formed 800 g waters, hence, humidity of air considerably increases.
At application of polymeric building materials (plastic) probably pollution of the air environment of premises by free monomeasures, phenol, formaldehyde, and also the flying and toxic substances which are a part of various additives to polymeric materials (from-verditeli, accelerators). Them concern dibutilftalat, gidroperekis izopropilbenzola, etc.
Along with it together with a dust in air of the closed premises the considerable quantity of various microorganisms, including pathogenic gets. Air of premises where there is a patient or a bacilli carrier is especially dangerous. Thus microorganisms get to air with saliva droplets, are sprayed at conversation, a sneezing, cough. Inhalation of such air can make the healthy person the patient, be the reason of occurrence of such diseases, as a tuberculosis, a flu, a scarlet fever, a measles, a whooping cough, a diphtheria, a chicken pox, etc.
The factors Set forth above promoting pollution of the air environment of premises, cause obligatory replacement of room air with pure external air. Such change of air or maintenance of sufficient air exchange is reached by means of ventilation. The number showing, how many time within an hour air will indoors be replaced external, is called as frequency rate of air exchange. Frequency rate of air exchange depends on following factors: cubic capacities of a premise, quantity of people indoors, character of performed work, quantity of sources of air pollution. 30-35 m should be entered into premises at the rate on one adult person 3 , the child till 10 years - 12 20, is more senior 10 years - 20-30 m 3 air in 1 ch.
For premises where there is a heavy physical work (the industrial enterprises, sports halls), and also in hospital chambers the ventilation volume should be more. So, in sports halls 90 m 3 air on 1 person in 1 ch, in industrial premises - 70 m 3 and more are required.
Sufficient air exchange is carried out by means of natural and artificial ventilation. Natural ventilation is the air exchange occurring under the influence of a difference of temperatures of external and room air. For natural ventilation the essential role is played also by a difference of pressure and a wind pressure. However sufficient air exchange of premises is not always provided for the account infiltratsii air through a time of building materials of external walls, thinnesses and small cracks in designs of buildings. Exist also means of strengthening of natural ventilation: window leaves, transoms, ventilating channels, podokonnye pritochnye adaptations, etc. Through window leaves and the transoms arranged in windows, there is an air exchange for what the window leaf area should be not less than 0,3 m 2 . However through a window leaf in a premise the stream of cold air on which heating some time is necessary that extends airing time arrives. The transom is more perfect device as, settling down in the top part of a window, excludes direct action of cold air on the person and, opening under a corner 45 ° to a window surface, directs air arriving in a premise to a ceiling. Having mixed up with warm air of the premise, arrived external air falls to a zone of breath of people already warmed up. It allows to hold a transom opened long time.
More effective air exchange is observed at through airing when in apartment open window leaves or transoms of the windows arranged in opposite external walls. Thus full change of air is provided for 3-5 minutes
The natural exchange of air Amplifies at the device of the special exhaust channels located in walls. Exhaust apertures of such channels should settle down in the top part of a wall as nagretyj air indoors rises upwards. SNiP Н-33-75 ' Norms of designing. Heating, ventilation and an air conditioning ' oblige suit these channels in kitchens, toilets, bathing. Exhaust channels unite in modular collectors which are brought to the exhaust mines located on a roof.
In premises where there is a considerable quantity of people or air it is considerably polluted, natural ventilation cannot provide the necessary air exchange. Then arrange artificial mechanical ventilation. Artificial ventilation can be local (for one premise) and central (for all building). It is not connected with fluctuations of temperature of external air, operates constantly and in regular intervals by means of special pobuditelej (fans). The central artificial ventilation can be pritochnoj, exhaust and combined (pritochno exhaust).
If air exchange strengthen by means of artificial giving of external air such ventilation is called as artificial pritochnoj. Air submitted thus should be pure with the defined temperature and the humidity providing good state of health of the person. Therefore constructions are necessary for clearing and heating of air. The place of a fence of air should be located far from pollution sources by its dust, gases and at height not less than 2 m from a soil surface. After a fence air passes pyleotstojnuju the chamber, filters and is warmed up, passing over heating devices. Cleared and warmed-up air moves in a premise, and room air leaves natural by (through window leaves, transoms, a time of building materials).
At the device of exhaust ventilation air from a premise leaves mechanical by, and inflow of pure air is carried out through windows, cracks, a time of walls.
At the device of a forced-air and exhaust ventilation and inflow, and air extract are carried out mechanical by. Prevalence of one kind of ventilation over another is thus possible. For example, indoors, from which air should not get in the next premises (kitchen, a lavatory, etc.), the extract should prevail over inflow, and indoors where cleanliness of air is especially necessary (operational), inflow should prevail over an extract. Therefore frequency rate of air exchange on inflow. ^oboznachajut a sign ' + ', and on an extract - a sign ' - '. For example, in operational ventilation conditions are characterised as +6,-5. It means, that in the given premise moves in 1ч sixfold, and is taken - fivefold volume of air in relation to premise volume.
Recently the air conditioning which is most a perfective aspect of artificial ventilation is widely applied. By means of conditioners in premises necessary parametres of a microclimate (temperature, humidity, air movement) are created. For this purpose in conditioners air is cleared, warmed up or cooled, humidified, i.e. Necessary microclimatic conditions are automatically supported.
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