ertain boilers will, when operated at ordinary ratings,
handle poor feed water and deliver steam in which the moisture content
is not objectionable. When these same boilers are driven at high
overloads, there will be a direct tendency to prime and the percentage
of moisture in the steam delivered will be high. This tendency is the
result of the lack of proper circulation and once more there is seen the
advantage of the headers of the Babcock & Wilcox boiler, resulting as it
does in the securing of a positive circulation.

In the design of the Babcock & Wilcox boiler sufficient space is
provided between the steam outlet and the disengaging point to insure
the steam passing from the boiler in a dry state without entraining or
again picking up any particles of water in its passage even at high
rates of evaporation. Ample time is given for a complete separation of
steam from the water at the disengaging surface before the steam is
carried from the boiler. These two features, which are additional causes
for the ability of the Babcock & Wilcox boiler to deliver dry steam,
result from the proper proportioning of the steam and water space of the
boiler. From the history of the development of the boiler, it is evident
that the cubical capacity per horse power of the steam and water space
has been adopted after numerous experiments.

That the "dry pipe" serves in no way the generally understood function
of such device has been pointed out. As stated, the function of the "dry
pipe" in a Babcock & Wilcox boiler is simply that of a collecting pipe
and this statement holds true regardless of the rate of operation of the
boiler.

In certain boilers, "superheating surface" is provided to "dry the
steam," or to remove the moisture due to priming or foaming. Such
surface is invariably a source of trouble unless the steam is initially
dry and a boiler which will deliver dry steam is obviously to be
preferred to one in which surface must be supplied especially for such
purpose. Where superheaters are installed with Babcock & Wilcox boilers,
they are in every sense of the word superheaters and not driers, the
steam being delivered to them in a dry state.

The question has been raised in connection with the cross drum design of
the Babcock & Wilcox boiler as to its ability to deliver dry steam.
Experience has shown the absolute lack of basis for any such objection.
The Babcock & Wilcox Company at its Bayonne Works some time ago made a
se