Air Conditioning

The term air conditioning in its broadest sense means control of any or all the physical or chemical qualities of the air within a structure. More particularly, it includes the simultaneous control of temperature, humidity, purity of the air (dust, bacteria, odors, toxic gases, ionization) most of these factors affect in greater or lesser degrees human health or comfort. The term is broad enough to embrace what­ever other additional factors may be found desirable for maintain­ing the atmosphere of occupied spaces at a condition best suited to the physiological requirements of the human body.

Внеаудиторное чтение, 3 семестр

Часть 2 Water-Supply and Sewage Disposal

None of you has probably ever thought about what is the most important item in the life of any town. Some think it is the trans­port, the others — electricity, still others may say something else and only very few will mention water-supply and sewage dispo­sal. That is quite understandable, for all the water-supply and sewage systems are hidden underground.

Conduits like arteries and blood vessels in the human orga­nism are located underground together with other communica­tions. Hundreds of thousands of cubic metres of water pass along the conduits (pipe lines).

In towns water is consumed for domestic and sanitary purpos­es as well as for, fire protection. In industrial enterprises great quantities of wafer are needed for technological purposes. The amount of water needed for a big consumer like a metallurgical combine is several times greater than that for a big town with a population of 1,5 mln people. Special recirculating systems are to be constructed for such enterprises as their water demand exceeds the debit of the water sources available.

There is not a single branch of the national economy that could do without water of some quality in a certain amount.

The modern water-supply and sewage disposal are a complicated system comprising all kinds of engineering structures used, for industrial and domestic purposes as well as for drainage, purification and disposal of sewage.

If we follow the flow of water through all the water supply and sewage works we shall first come to an area where the in­takes, pumping stations, purifying equipment and various reser­voirs are located. Even the temporary presence of strangers in this zone is prohibited, nor any construction is allowed that is not directly connected with water supply.

By means of powerful pumps water is taken from the source of supply be it a river, a lake or a well. It is chlorinated to dest­roy all the disease producing (pathogenic) organisms which may be present in the untreated water.

The water flows to the settling base where all the matter in suspension is removed. From the setting basins water goes to filters for a more thorough purification.

Having reached the town, the water enters house connections and is fed to various household appliances such as sinks, baths, showers, lavatories, wash-stands and so on.

After usage water enters the drainage system, goes to the sewage collector and afterwards is subjected to biological treat­ment in special sewage treatment works.

Sewage first passes through screens where coarse impurities are detained. Next it is stored in precipitators of horizontal (late­ral), vertical or of radial type.

If the degree of purification is sufficient the sewage is disinfected by means of lime and discharged into some water basin.

If further purification is needed the sewage is directed to biological filters for decomposition of organic impurities. Then the effluent is again allowed to settle. And only after that the purified and disinfected sewage may be discharged into some stream or body of water. But we shall not dwell on that here.

Suffice it to say that the problem of water supply for towns and enterprises and its disposal after utilization (and purifica­tion) is one of the most important problems which are of greatest economic significance.