VENTILATION AND HEALTH IN ENGLISH

                                                    

                               VENTILATION AND HEALTH IN ENGLISH

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VENTILATION-

}  Ventilation means providing air. it is a process of replacement of indoor air with fresh outdoor air. It is movement of indoor air to out and outdoor air to inside a closed area.

STANDARDS OF VENTILATION-

}  Cubic space- fresh air supply of 3,000 c.ft. per person per hour is a good standard for air requirement.  It is observed that the amount of carbon dioxide due to respiration is not more than 2 parts in 10,000 parts of air, the air of the rooms is considered fresh

}  Air change- Air change is more important than the cubic space requirement. It is recommended that in the living rooms, there should be 2 or 3 air changes in one hour; in work rooms and assemblies 4 to 6 air changes.

}  Floor space- floor space per person is also a good standard and more important than cubic space.  heights over 12 feet are not taken into account. The optimum floor space requirements per person vary from 50 to 100 sq.ft.

TYPES OF VENTILATION-

Ventilation is classified as-

}  Natural ventilation and

}  Mechanical ventilation

NATURAL VENTILATION-

}  Natural ventilation is the simplest system of ventilating small houses, schools and offices. In this method, certain forces work which are present in nature. These are:

}  The wind- The wind is have a natural force. When it blows through a room, it is called perflation. Some times due to obstruction it exerts a suction action at its tail end - this is called aspiration. Doors and windows facing each other provide "cross-ventilation". It is best system of natural ventilation

}  Diffusion -Diffusion is the movement of molecules from high concentration to low concentration. It is a very slow process of ventilation and ineffective if it is the only of ventilation.

}  Temperature difference- Air flows from high density to low density. Hot air rises up and escapes from openings (ventilators) provided in the room. The outside air which is cooler and more dense will enter the room through doors and windows. 

MECHANICAL VENTILATION-

}  Mechanical or artificial ventilation may be of the following types :

}  (1) Exhaust ventilation. - In this system, air is extracted or exhausted to the outside by electiric exhaust fans. As air is exhausted, a vacuum is created which results in fresh air to enter the room through windows, doors and other inlets.

This system is generally provided in large halls and auditorium for removal of vitiated air. The exhaust fans are fixed in the external walls, high up near the roof which facilitate removal of the upper layers of the heated light air.

}  (2) Plenum ventilation.- Plenum ventilation is opposite to exhaust system. In this system, fresh air is blown into the room by electric fans so as to create a positive pressure, and displace the vitiated air. Air is delivered through ducts at desired points.

}  (3) Balanced ventilation. - This system of ventilation is a combination of the exhaust ventilation and plenum ventilation systems. The blowing fan must balance the exhaust fan and air is circulated in continuous balanced process.

}  (4) Air conditioning. Air conditioning is defined as "the simultaneous control of all, or at least the first three of those factors affecting both the physical and chemical conditions of the atmosphere within any confined space or room.

}  These factors include temperature, humidity, air movement, distribution, dust, bacteria, odours and toxic gases, most of which affect  the human health and comfort".

}  The air is filtered when drawn into an air-conditioner system from the room. Excess humidity is removed and the air is circulated back into the room after heating or cooling it, to bring room temperature to required comfort zone.