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The velocity of water entering a suction pipe depends upon two things, the vacuum in the pipe and the vertical lift of the water. The longer the suction pipe, vertically, the greater the frictional resistance to the flow of water; the flow of water through small discharge pipes should not exceed four hundred feet per minute, and for large pipes five hundred feet per minute.
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A locomotive-boiler compound. The lines of a certain great R. R. traverse a country where the water is very hard and they are compelled to resort to some method of precipitating the lime that is held in solution. After many tests and experiments they have made a compound and use it as follows: in a barrel of water of a capacity of fifty gallons they put 21 lbs. of carbonate of soda, or best white soda ash of commerce, and 35 lbs. of white caustic soda; the cost, per gallon, is about 21⁄2 cents. The compound is carried in this concentrated form, in calomine cans on the tender of each locomotive. A certain amount, according to the necessities of the case, is poured into the tender at the water tank at each filling. This amount is determined by analysis, and varies all the way from two to fifteen pints for two thousand gallons of water. The precipitating power of this compound may be taken roughly at 2⁄3 of a pound of the carbonate of lime, or equivalent amount of other material, per pint of the compound. On their western lines where they are dealing with alkali waters and those containing sulphates, the company use merely 60 pounds of soda ash to a barrel of water. When the water is pumped into the boiler the heat completes the precipitation and aggregation of the particles, and this does away with all trouble of the boiler or injector tubes clogging up.
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It has been recently determined by some German experimenters that sugar effects a strong action in steam boilers; it has an acid reaction upon the iron which dissolves it with a disengagement of hydrogen. The amount of damage done increases with the amount of sugar in the water. These results are worthy of note in sugar refineries and places where sugar sometimes finds its way into the boilers by means of the water supplied. The experiments in question also show that zinc is strongly attacked by sugar; copper, tin, lead and aluminium are not attacked.
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White oak bark, used by tanners, has an excellent effect on boiler incrustations. It may be used as follows: Throw into the tank or reservoir from which the boilers are fed a quantity of bark in the piece, in sufficient quantity to turn the water to a light brown color. Repeat this operation every month at least, using only half the quantity after the first month. Add a very small quantity of the muriate of ammonia, about one pound for every 2,000 gallons of water used. This will have the effect of softening as well as disintegrating the carbonate of lime and other impurities deposited by the action of evaporation.
Note.—Care must be exercised in keeping the bark, as it becomes broken up, from the pump valves and blow-off valves. This may be accomplished by throwing it into the reservoir confined in a sack.