rvice and banking others, or a variable capacity from
all boilers in service.

The opportunity is again taken to indicate the very general character of
any statements made relative to the economical load for any plant and to
emphasize the fact that each individual case must be considered
independently, with the conditions of operations applicable thereto.

With a thorough understanding of the meaning of boiler efficiency and
capacity and their relation to each other, it is possible to consider
more specifically the selection of boilers.

The foremost consideration is, without question, the adaptability of the
design selected to the nature of the work to be done. An installation
which is only temporary in its nature would obviously not warrant the
first cost that a permanent plant would. If boilers are to carry an
intermittent and suddenly fluctuating load, such as a hoisting load or a
reversing mill load, a design would have to be selected that would not
tend to prime with the fluctuations and sudden demand for steam. A
boiler that would give the highest possible efficiency with fuel of one
description, would not of necessity give such efficiency with a
different fuel. A boiler of a certain design which might be good for
small plant practice would not, because of the limitations in
practicable size of units, be suitable for large installations. A
discussion of the relative value of designs can be carried on almost
indefinitely but enough has been said to indicate that a given design
will not serve satisfactorily under all conditions and that the
adaptability to the service required will be dependent upon the fuel
available, the class of labor procurable, the feed water that must be
used, the nature of the plant's load, the size of the plant and the
first cost warranted by the service the boiler is to fulfill.

TABLE 60

ACTUAL EVAPORATION FOR DIFFERENT PRESSURES AND TEMPERATURES OF FEED
WATER CORRESPONDING TO ONE HORSE POWER (34-1/2 POUNDS PER HOUR FROM AND AT 212 DEGREES FAHRENHEIT)

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