The Locomotive - Lighthouse Survival Blog

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PUBLISHED BY THE HARTFORD STEAM BOILER INSPECTION AND INSURANCE COMPANY.
New Series — Vol. XV. HARTFORD, CONN., SEPTEMBER, 1894. No. 9.
The Formation of Scale in Boilers, and in Feed, Circulating", and
Blow-off Pipes.
If we could run boilers with perfectly pure water — for example, with water that
had previously been distilled — many of the difficulties encountered in actual practice
would never arise, and the fireman's duties and responsibilities would be correspond-
ingly lessened and simplified. Unfortunately, this ideal condition of things cannot be
realized. We cannot afford to use distilled water, and in most cases feed-water has to
be taken in accordance with that mode of selection which is known to the world at
large as " Hobson's choice"; that is, we have to take what we can get. In cities and
towns good water may usually be had from the city mains ; but in sparsely populated
districts the manufacturer has to depend upon wells or upon running streams, which
Fig. A Feed-Pipe nearly Sealed up by Scale.
usually serve as sewers for the families of the employes who live along their banks. If
there is organic matter in the water trouble is likely to result from corrosion and wast-
ing of the boiler plates; and wells, which are notorious for the "hardness" of the
water they furnish, are apt to provide the manufacturer with more scale-forming matter
than he can comfortably handle. The water supply of cities is selected with special
reference to its fitness for drinking purposes, and for this reason city water is usually
comparatively free from organic matter. In most cases it consists of surface water
which has not penetrated deeply into the soil, and which has, therefore, had but little
opportunity of dissolving mineral matter; but in regions where lime and magnesia
abound the city water is likely to be more or less charged with compounds of these sub-
stances, and under these circumstances it may be as " hard" as the general run of well
waters, and may deposit a copious scale.