Part 12 (1/2)

Corrosion--Corrosion, or a che to the actual destruction of the boilerproperties of the feed water It results from the presence of acid, either free or developed[15] in the feed, the adalvanic action In boilers it takes several for, which consists of isolated spots of active corrosion which does not attack the boiler as a whole

2nd General corrosion, produced by naturally acid waters and where the amount is so even and continuous that no accurate esti, which, while largely a mechanical action which may occur in neutral waters, is intensified by acidity

Foa--This phenomenon, which ordinarily occurs aters contarowths, is due to the fact that the suspended particles collect on the surface of the water in the boiler and render difficult the liberation of stea to that surface It so carbonates in solution in which a light flocculent precipitate will be forain, it is the result of an excess of sodium carbonate used in treatetable oil finds its way into the boiler

Pri off of steam from a boiler in belches, is caused by the concentration of sodium carbonate, sodium sulphate or sodium chloride in solution Sodium sulphate is found in nesium sulphate is precipitated with soda ash

Treatment of Feed Water--For scale for ingredients, is along two main lines: 1st, by chemical means by which such impurities as are carried by the water are caused to precipitate; and 2nd, by the means of heat, which results in the reduction of the power of water to hold certain salts in solution The latter method alone is sufficient in the case of certain teeneral, is used in connection with a che further into detail as to the treatment of water, it may be well to define certain terms used

_Hardness_, which is the most widely known evidence of the presence in water of scale-for matter, is that quality, the variation of which makes it more difficult to obtain a lather or suds from soap in one water than in another This action is made use of in the soap test for hardness described later Hardness is ordinarily classed as either temporary or per carbonates of li at 212 degrees and which, if they contain no other scale-forredients, become ”soft” under such treat h terees Fahrenheit or more The scale of hardness is an arbitrary one, based on the nuallon and waters allon, soft water; 10-20 grain per gallon, allon, very hard water

_Alkalinity_ is a general ter co acids

_Causticity_, as used in water treat the presence of an excess of lih such presence would also indicate alkalinity, the term is arbitrarily used to apply to those hydrates whose presence is indicated by phenolphthalein

Of the cheeneral processes:

1st Li bicarbonates of linesia Slacked lient used This combines with the carbonic acid which is present, either free or as carbonates, to form an insoluble monocarbonate of li their carbonic acid, thereby become insoluble and precipitate

2nd Soda Process The soda process is used for waters containing sulphates of linesia Carbonate of soda and hydrate of soda (caustic soda) are used either alone or together as the reagents

Carbonate of soda, added to water containing little or no carbonic acid or bicarbonates, decomposes the sulphates to fornesia which precipitate, the neutral soda re in solution If free carbonic acid or bicarbonates are present, bicarbonate of lih under the action of heat, the carbon dioxide will be driven off and insoluble monocarbonates will be foretic action, it being presumed that the caustic soda absorbs the carbonic acid, becomes carbonate of soda and acts as above

3rd Lime and Soda Process This process, which is the coenerally used in water purification

Such a nesia are contained in the water, together with such quantity of carbonic acid or bicarbonates as to impair the action of the soda Sufficient soda is used to break down the sulphates of linesia and as much lime added as is required to absorb the carbonic acid not taken up in the soda reaction

All of the apparatus for effecting such treatment of feed waters is approximately the sa in the ents

Thewater treated by an apparatus of this description follow

When properly treated, alkalinity, hardness and causticity should be in the approximate relation of 6, 5 and 4 When too much lime is used in the treatment, the causticity in the purified water, as indicated by the acid test, will be nearly equal to the alkalinity If too little lime is used, the causticity will fall to approximately half the alkalinity The hardness should not be in excess of two points less than the alkalinity

Where too great a quantity of soda is used, the hardness is lowered and the alkalinity raised If too little soda, the hardness is raised and the alkalinity lowered

Alkalinity and causticity are tested with a standard solution of sulphuric acid A standard soap solution is used for testing for hardness and a silver nitrate solutionwhether an excess of lime has been used in the treatment

Alkalinity: To 50 cubic centimeters of treated water, to which there has been added sufficient e to color it, add the acid solution, drop by drop, until thered As the acid solution is first added, the red color, which shows quickly, disappears on shaking the mixture, and this color disappears more slowly as the critical point is approached One-tenth cubic centiree of alkalinity

[Illustration: 2640 Horse-power Installation of Babcock & Wilcox Boilers at the Botany Worsted Mills, Passaic, N J]

Causticity: To 50 cubic centimeters of treated water, to which there has been added one drop of phenolphthalein dissolved in alcohol to give the water a pinkish color, add the acid solution, drop by drop, shaking after each addition, until the color entirely disappears One-tenth cubic centiree of causticity