AN IMPROVED SAFETY APPARATUS APPLICABLE TO STEAM GENERATORS, AND OTHER VESSELS IN WHICH LIQUIDS ARE HEATED
Year: 1875

page_text: PROVISIONAL SPECIFICATION left by William Henry Riley at the
Office of the Commissioners of Patents, with his Petition, on the
13th August 1875.
I, WILLIAM HENRY RILEY, of Portsmouth, in the County of South-
ampton, Assistant Engineer in the Royal Navy, do hereby declare the
nature of the said Invention for "AN IMPROVED SAFETY APPARATUS APPLICABLE
TO STEAM GENERATORS, AND OTHER VESSELS IN WHICH LIQUIDS ARE HEATED," to be
as follows:-
This Invention relates to a simple and effective contrivance for
obviating the danger and inconvenience arising from the lowering of the
level of water or other liquid in the vessel in which it is being heated;
the said contrivance being either connected with an indicating or alarm
apparatus for warning the attendants, or with a feed apparatus for
supplying the said vessel with water or other liquid to replace that
which has been lost by evaporation or connected with apparatus for
extinguishing the fires.
The said contrivance consists essentially of a metal tube of any
convenient form placed horizontally or nearly so, and firmly fixed at
each end inside a steam generator or other vessel in which liquid is to

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be heated, and situate at or about the level at which the liquid is to be
maintained. This tube which I designate a safety tube" must be so
disposed that the heating agency shall act on one surface thereof
(whether inside or outside), whilst the liquid to be heated or evaporated
is in contact with the other surface whether on the inside or outside of
the tube, as may be found best suited to the form of boiler or vessel to
which the said tube is applied.
When heat is being transmitted through the sides of the tube to the
liquid, and the level of the liquid in the vessel is falling so as to uncover
or partially uncover the tube, the said tube becomes hotter than when
covered to a greater extent by the liquid, and it therefore expands and
increases in length, but as its ends are firmly secured to the sides of the
steam generator or other vessel it can only yield in a lateral direction,
and it is this lateral yielding or deflection of the tube under undue
expansion which is rendered available for obviating the danger and
inconvenience arising from the lowering of the level of the water or
liquid in the vessel in which it is being heated or evaporated. On the
level of the water rising again the temperature of the tube is lowered,
consequently it contracts and resumes its previous condition ready to do
duty again when required.
In applying the above tube to a marine boiler, for example, it would
be made to extend from the combustion chamber to the front tube plate,
and a rod may be attached at one end near the middle of the tube whilst
its other end would pass through the top of the boiler, transmitting the
lateral deflecting motion of the tube to an indicator or gauge for
warning the attendants when the tube had become extra heated owing
to the level of the water or liquid falling about the tube. It is preferred
that the tube be placed at such an elevation as to ensure its acting
before the water falls to a dangerous level. If the tube occupied one of
the positions of the ordinary boiler tubes, the water on falling about it
would leave several of the boiler tubes exposed, rendering it dangerous
to feed the boilers with water whilst in that condition. In this case the
fires should be put out so soon as the gauge or other indicator has given
warning that the water has fallen below the tube.