THE PREVENTION OF STEAM BOILER EXPLOSIONS
Year: 1855

page_text: LETTERS PATENT to William Kemble Hall, of 86, Cannon Street,
London, Engineer, for the Invention of "THE PREVENTION OF STEAM
BOILER EXPLOSIONS."
Sealed the 8th February 1856, and dated the 12th November 1855.
PROVISIONAL SPECIFICATION left by the said William Kemble Hall
at the Office of the Commissioners of Patents, with his Petition, on the
12th November 1855.
I, WILLIAM KEMBLE HALL, of 36, Cannon Street, London, Engineer, do
hereby declare the nature of the said Invention for "THE PREVENTION OF STEAM
BOILER EXPLOSIONS" to be as follows:-
A valve, opening outwards and communicating with the water in the boiler,
is retained in its seat, and kept closed by a float and weight, or by a rod,
soldered at one or more points to the beating surface of the boiler in such a
manner, that when, by negligence or otherwise, the level of the water has
fallen below the flues, the valve is released and opened by the pressure of the
steam, and the water blown from the boiler.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Kemble Hall in the Great Seal Patent Office on
the 9th February 1856.
TO ALL TO WHOM THESE PRESENTS SHALL COME, WILLIAM
KEMBLE HALL, of 36, Cannon Street, London, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twelfth day of November, in the year of our Lord
One thousand eight hundred and fifty-five, in the nineteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said William Kemble Hall, Her special licence that I, the said William
Kemble Hall, my executors, administrators, and assigns, or such others as I,
the said William Kemble Hall, my executors, administrators, and assigns,
should at any time agree with, and no others, from time to time and at all
times thereafter during the term therein expressed, should and lawfully might
make, use, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for "THE
PREVENTION OF STEAM BOILER EXPLOSIONS," upon the condition (amongst others)
that I, the said William Kemble Hall, my executors or administrators, by an
instrument in writing under my, or their, or one of their hands and seals,
should particularly describe and ascertain the nature of the said Invention,
and in what manner the same was to be performed, and cause the same to
be filed in the Great Seal Patent Office within six calendar months next and
immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said William Kemble Hall, do hereby declare
the nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:-
The object of my Invention is to discharge the water and steam from a
boiler, when, by negligence or otherwise, the surface of the water has fallen to
a dangerous extent, and allowed the boiler to become overheated. And the
Invention consists of a valve communicating with the water, and retained in
its seat and kept closed by a float and weight, or by a rod, soldered at one or
more points to the beating surface of the boiler. When the surface. of the
water has fallen below the flues, the valve is released by the working of the
float, or by the melting of the solder or fusible metal employed to detain
the rod, and is opened by the pressure of the steam, and the water and the
steam are thus blown from the boiler.

page_text: The accompanying Drawing represents the valve and its connections, con-
stituting my Invention. The same letters in the various Figures refer to
similar parts.
Fig. 1 is a section of an ordinary cylindrical boiler, with a single internal
flue fitted with this apparatus; Fig. 2 is a side elevation of the apparatus as
applied in the preceding Figure. a is a valve communicating with the water
in the boiler by a pipe b; c, d, e, is a rod, serving as a stem to the valve a,
made in two parts, jointed at d for convenience of construction, and termi-
nating at its lower end e with a button or flange. The upper end c of this rod
or valve stem is cut with a screw thread, and furnished with a nut, by which
the valve may be secured tightly in its seat. f is a cup, bolted or otherwise
fastened to the upper portion of the flue, in which the valve stem c, d, e, is
secured with tin or any other readily fusible metal alloy or other compound.
When the tin in the cup f is melted, the valve a is opened by the pressure of
the steam, and the water and steam discharged from the boiler through the
pipe b. The cupf should be made of copper, or other good conductor of heat,
and should be placed in the position first exposed to the action of the heat by
the falling of the surface of the water, or in any other position where, by mal-
formation of the boiler or otherwise, the plates are most likely to become
unprotected by water from the action of the fire. 9 is a washer of vulcanized
india-rubber, placed under the nut on the valve stem, by which the valve is
secured to its seat, for the purpose of compensating by its elasticity for any
difference in the expansion of the boiler and its flue and the valve stem; his
a pipe by which the water and steam when discharged from the boiler may bo
employed to extinguish the fire, or conduct it to any other point that may be
desired; the pipe 6 may also be used as the inside feed pipe from the force
pump.
b
Fig. 3 represents the application of my Invention to a boiler with external
flues; Fig. 4 shows its arrangement when applied to a boiler with two internal
flues.
Figs. 5 and 6 shew a form of the cup f for holding the fusible metal with
which the valve rod is secured, in a manner different from that shewn in
Figs. 1 and 2.
Fig. 7 is a modification of the joint d in the valve rod c, d, e, by which the
inequalities of expansion may be compensated for by the elasticity of the joint
pin, independent of the ring of vulcanized india-rubber, represented at gin
Fig 1. The same purposes may be accomplished by the use of an ordinary
helical spring.

page_text: Having described my Invention, and illustrated it by the Figures contained
in the Sheet of Drawings hereunto annexed, I wish it to be understood that I
do not claim any of the mechanical parts separately, nor do I confine myself
to the precise combination of the valve, fusible metal cup, and intervening
elastic substance as described, as they may be varied without departing from
the nature of my Invention; but what I do claim is, the connecting of a valve
with an apparatus that ensures its opening when the boiler becomes danger-
ously overheated, whereby the water and steam may be discharged from the
boiler, and employed, if desired, to extinguish the fire.
In witness whereof, I, the said William Kemble Hall, have hereunto set
my hand and seal, this Thirtieth day of January, One thousand eight
hundred and fifty-six.
WILLIAM KEMBLE HALL. (L.B.)
Witness,
WILLIAM SMITH,
10, Salisbury St., Adelphi.