IMPROVEMENTS IN APPARATUS FOR PREVENTING THE EXPLOSION OF STEAM BOILERS
Year: 1860

page_text: LETTERS PATENT to David Davies, of the City of Manchester. Engineer.
and James Allen, of the same Place, Brassfounder, for the Invention of
"IMPROVEMENTS IN APPARATUS FOR PREVENTING THE EXPLOSION OF STEAM
BOILERS."
and James Allen, of the same Place, Brassfounder, for the Invention of
"IMPROVEMENTS IN APPARATUS FOR PREVENTING THE EXPLOSION OF STEAM
BOILERS."
Sealed the 5th March 1861, and dated the 15th September 1860.
PROVISIONAL SPECIFICATION left by the said David Davies and James
Allen at the Office of the Commissioners of Patents, with their Petition,
on the 15th September 1860.
We, DAVID DAVIES, of the City of Manchester, Engineer, and JAMES
ALLEN, of the same Place, Brassfounder, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN APPARATUS FOR PREVENTING THE EXPLOSION
OF STEAM BOILERS," to be as follows:-
The object of our Invention is to admit steam from the boiler to the fire
when the pressure of the steam exceeds the desired limit, and when the level
of the water in the boiler is too low.
Our improvements consist in a duplex or compound safety valve, the upper
valve being larger than the lower one; the seatings of both the valves are'
placed in a case fixed to the shell of the boiler above the fire-grate; the lower
valve is connected with the fire-grate by a pipe furnished with fusible safety
plugs, placed in such a position that they are exposed when the level of the

page_text: water is lower than that at which it is safe to work. When the pressure of
steam exceeds the desired limit the upper or larger valve is raised by the
steam entering through ports in the case, and as the upper and lower valves
are cast or connected together the rising of the upper valve lifts the lower one,
and thus allows a portion of the steam to pass down the pipe on to the fire,
which is thus subdued or partially put out until the pressure of steam is
reduced to allow the valves to return to their seatings. The same action takes
place when the fusible plugs are exposed, as the heat from the fire will melt
them when. unprotected by the water, consequently explosions from over-
pressure of steam and deficiency of water are prevented by means of our
improvements.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said David Davies and James Allen in the Great Seal Patent
Office on the 13th March 1861.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, DAVID
DAVIES, of the City of Manchester, Engineer, and JAMES ALLEN, of the same
Place, Brassfounder, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fifteenth day of September, in the year of our Lord
One thousand eight hundred and sixty, in the twenty-fourth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto us,
the said David Davies and James Allen, Her special licence that we,
the said David Davies and James Allen, our executors, administrators,
and assigns, or such others as we, the said David Davies and James
Allen, our 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 "IMPROVEMENTS IN APPA-
RATUS FOR PREVENTING THE EXPLOSION OF STEAM BOILERS," upon the condition
(amongst others) that we, the said David Davies and James Allen, our
executors or administrators, by an instrument in writing under our, or their,
or one of our or their hands and seals, should particularly describe and ascer-
tain 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

page_text: Office within six calendar months next and immediately after the date of the
said Letters Patent.
NOW KNOW YE, that we, the said David Davies and James Allen,
do hereby declare the nature of our said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained in and
by the following statement (that is to say) :-
The nature of our Invention consists in an improved apparatus applicable
to steam boilers for admitting steam to the fire when the pressure of the steam
in the boiler exceeds the desired limit; also for admitting steam to the fire
when the level of the water in the boiler descends below the level at which it
is considered safe to work, the object being in both cases to damp the fire or
extinguish it, thereby preventing the explosion of the boiler.
In order that our Invention may be fully understood and readily carried
into effect, we will proceed to describe the accompanying Drawing, reference
being had to the figures and letters marked thereon.
Figure 1 is a transverse section of an ordinary circular steam boiler, to
which our improved apparatus is applied; and Figure 2 is a section through
the apparatus, drawn to a larger scale. a is the outer shell of the boiler;
b, the internal flue; and c, the fire-grate, which parts are made in the usual
manner; d is the case fixed to the outer shell of the boiler, and provided with
two seatings for the compound safety valve e, e¹, the upper portion of which is
weighted by the lever f, or in any other convenient manner. The sides of the
case d are perforated to admit the steam from the boiler to the under side of
the safety valve e. To the lower part of the case d is attached the upper end
of the pipe g, the lower end of which is attached to the crown of the internal
flue b; this pipe is bent to allow for expansion, and it is furnished with fusible
plugs at h, placed below the ordinary working level of the water in the
boiler.
The action of this apparatus is as follows:-When the pressure of steam is
sufficiently great to raise the safety valve e the valve e', which is either cast
with or attached to it, is also raised, and a portion of steam from the boiler
passes down the pipe 9, and diffuses itself over the fire, which is thus damped
or partially put out; the steam continues to escape through the safety valve e
and valve e, until its pressure is sufficiently reduced to allow the valves to
return on to their seatings. By this means a considerable saving in fuel and
water is effected, and the firemen may rely upon finding the fire in good con-
dition, and the water at its proper level, when he arrives to start the engine in
the morning or after meal times. When the level of the water descends

page_text: below the fusible plugs they will melt by the extra heat, and allow the steam
and water to descend through the pipe 9 to the fire. We wish to remark that
the fusible plugs may be attached in the ordinary manner to the crown of the
flue b, or entirely dispensed with.
Our Invention may also be modified by attaching the seating of the lower
valve e¹ to the crown of the flue b, and connecting the rod of the valve to the
weighted lever f of the safety valve e; in this case the valve rod would have
to pass through a stuffing box fixed to the outer casing a, or the rod of the
valve e may be connected to a lever placed within the boiler, and jointed to
the spindle of the safety valve e.
Figure 3 represents a modification of our improved apparatus, the con-
struction of which renders it peculiarly suitable for being applied to safety
valves of the ordinary construction; in this instance the double seating i, i¹, of
the valves e, e¹, fits in the case d, and the pipe g is attached to a flange cast
with the double seatings; the guide wings are in this case attached to the
smaller valve instead of to the larger one, as shewn in Figure 2.
Having thus described the nature of our Invention, and the manner of
performing the same, we declare that we claim the improvements in apparatus
as shewn and as described, by means whereof the explosions of steam boilers
are prevented.
In witness whereof, we, the said David Davies and James Allen, have
hereunto set our hands and seals, the Twelfth day of March, in the
year of our Lord One thousand eight hundred and sixty-one.
מזעזם
DAVID DAVIES. (L.B.)
JAMES ALLEN. (L.S.)
DAVID DAVIES. (L.S.)
JAMES ALLEN. (L.S.)