Handbook on engineering by Tulley Henry Charles

Author:Tulley, Henry Charles. [from old catalog]
Language: eng
Format: epub
Tags: Mechanical engineering
Publisher: St. Louis, Mo., Sold by H. C. Tulley & co
Published: 1900-03-25T05:00:00+00:00

water is used in a steam boiler a scale will gradually form, which will, iu a short time, become very troublesome.

(d) Organic impurities are present, to a certain extent, iu most waters. They are sometimes present in the water in sufficient quantities to give it a very decided color and taste.

The presence of organic matter in water is often dangerous to health, and may be a means of spreading contagious diseases, but has little or no bad effect in any water used for steam boilers. In general, water is regarded by engineers as being either soft, hard or salt.

Ebullition* — Is the motion produced in a liquid by its rapid conversion into vapor. When heat is applied to the bottom of a boiler, the particles of water in contact with the plates become heated and immediately expand, and becoming specifically lighter, pass upwards through the colder body of water above ; the heat of the furnace is in this way diffused throughout the whole body of water in the boiler by a translation of the particles of water from below upwards, and from top to bottom in regular succession. After a time this liquid mass becomes heated to a degree in which there is a violent agitation of the whole body of water, steam is given off and it is said to boil. The temperature at the boiling point of water, at ordinary atmospheric pressure, is 212° Fahr., and increases as the pressure of steam above it increases.

Distilled water for boilers is not to be recommended without some reservation. Chemically pure water, and especially water which has been redistilled several times, has a corrosive action on iron which is often very troublesome. The effect on steel plates by the use of water several times redistilled, such, for example, as that supplied for heating buildings, is well known ; information is yet wanting which shall point with certainty to the exact change which the water undergoes and explain why its action on or affinity for steel is so greatly intensified. It has been suggested as a means of neutralizing this corrosive action of the water, to

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