The Locomotive - Lighthouse Survival Blog

6 THE LOCOMOTIVE. [January.
In both of the cases shown above the boilers are led at the back end, and the feed-
valves were habitually left open : the assumption being, apparently, that when the
pump was started the water would enter both boilers equally. This is an unsafe
assumption, because it is well known that feed pipes are liable to choke up from a
variety of causes, especially when, as in Fig. 2, the bodies are fed and blown off
through the same opening. Feed-valves should alw^ays be in front, where the fireman
:;an reach them easily. A good man will not neglect them anyway, but it is better not
to tempt him to do so by putting them in an inconvenient place. Fig. 3, shows an
irrangement in which the feed-valves were at the front end of the battery. There was
a check-valve in the main feed pipe at C, but the boilers were not provided with
individual checks, as they should be. A part of the danger could be removed in this
case by putting in individual check-valves between the globe-valves shown in the cut
and the tee where the feed pipe branches. This would prevent the water from backing
out from either boiler into the other one. But in all of the cases shown thus far there is
the serious objection, that the feed water enters the boilers at the bottom. The shell
being chilled by the cool feed is subjected to severe strains, and leaky seams and
fractured plates are apt to result. Many persons find it hard to realize the magnitude
of the strains produced in this way, and are disposed to dispute with us when we urge
upon them the dangers to which the bottom feed subjects them. It is a matter of
experience, however, that ruptures are produced in this manner, and we have known
the bottom seams of a new boiler to be ruptured three times in six weeks from this very
cause. The strains produced by the chilling action of feed water can also be calculated,
and we hope to touch further upon this point in a future issue. The arrangement shown
in Fig. 3 is more objectionable from this point of view than the others, because the
feed enters at a hotter part of the boiler.
Figs. 4 and 5 show the arrangement of the feed pijjes that we recommend, and
experience has proven it to be entirely satisfactory. The main feed pipe runs along the
front of the boilers, as shown at FFF in Fig. 4, and branch pi])es are taken off by
means of tees. In each of these pipes there is a stop-valve, F, with a check-valve, C,
below it, and a union connection, U. The feed pipe enters the front head just above
the upper row of tubes, and after entering the boiler it passes down nearly to the back
head, as shown in Fig. 5. It then crosses over to the other side of the shell, and, turn-
ing downward, discharges between the shell and the tuljes. In this way the feed water
becomes well heated before discharging into the boiler, and its chilling action on the
shell is greatly lessened. The best place for the discharge of the feed water into the
boiler has been carefully considered, and we believe that that indicated in Fig. 5 is
freer from objection than any other that could be selected.
In connection with Fig. 2, we said that there should be a check-valve in the main
feed pipe. We do not wish to be understood as saying that tliere should always be a