A text-book on hygiene and pediatrics from a chiropractic standpoint

by J. H. Craven

By far the most satisfactory method of ventilating large buildings is the mechanical method. This is not practical for small buildings or homes because of the special devices that are required and the expense of operation. Mechanical ventilation may be accomplished by the plenum system, the vacuum system, or by the combined plenum and vacuum systems. The most desirable results are obtained when both systems are used and used in connection with the heating system. Heating and ventilating are so closely related that they must be considered one with the other. A poorly ventilated room is more difficult to heat and an improperly heated room is difficult to ventilate.

The plenum system consists of a fan to force the air into the rooms. These fans are run by water motors or electricity whereby the air is forced through ducts into the rooms. This system is made necessary by the great buildings, basements and large steamships, which could not be inhabited if natural ventilation was the only method employed.

The vacuum system consists of suction fans whereby the vitiated air is drawn out of the rooms and replaced by fresh air through the natural openings. In this way natural ventilation may be made more efficient, but this method in itself is not adequate for large buildings.

The two systems, vacuum and plenum, are commonly used together and when employed in connection with the heating device the very best results are obtained. The amount of air, the temperature and humidity, and the purity of the air may be regulated to a nicety in this way.

A complete system of vacuum and plenum consists of plenum fans for forcing the air into the rooms, vacuum or suction fans for the removal of vitiated air, the ducts for conducting the air to and from the rooms, the necessary machinery to run the fans, and a proper heating system whereby the air may be warmed in the winter and cooled by ice coils in the summer. It is also necessary to have a device for washing the air.

Washing the Air

As the air is drawn into the buildings by the plenum fan it is passed through a chamber where it is washed. This is done by forcing the air through a spray of water. A water curtain is formed by forcing water through perforated pipes placed across the chamber from each other and the water thus sprayed made to intercept. As the air passes through this curtain of water many of the impurities such as dust, cinders, bacteria, some of the gases, particles of decomposition, and epithelial cells, are removed. Washing does not remove carbon dioxide or bodily odors. Washing is one of Nature’s methods of cleaning the air as is seen in rain.

Central heating with washed air.

After the air is washed it is passed over tempering coils. In the winter the air is warmed and in the summer it is cooled in this way. The humidity is also controlled. It can thus be seen that this method, although rather expensive, is the only real method of ventilating large buildings satisfactorily.