Year: 1886

page_text: Date of Application, 30th Sept., 1886.
Complete Left, 10th June, 1887.
Complete Accepted, 26th July, 1887.
I, GEORGE DOWNING, of 8 Quality Court, Chancery Lane, in the County of
Middlesex, Patent Agent, do hereby declare the nature of my said invention to be as
follows:-
The object of my invention is to provide an improved arrangement of safety apparatus,
for the prevention of steam boiler explosions.
My invention consists of:-
1. An automatic alarm to the attendant, when the pressure exceeds the maximum
at which the generator is intended to be worked.
2. An automatic means of discharging the steam, when the pressure further increases
beyond such maximum working pressure.
And in order that my said invention may be particularly described and ascertained,
reference is hereby made to the accompanying drawings, in which similar letters of
reference indicate corresponding parts.
Fig. 1 is a sectional elevation; Fig. 2 is a front view, and Fig. 3 is a section on the
line xy of Fig. 1.
The apparatus is fixed to the boiler, by means of the flange N, the steam having
free access to the chamber A' by the pipe B ; and gaining access to the chamber A* in
the manner hereinafter mentioned.
The apparatus consists of a box formed in two halves, and bolted together, having
a thin diaphragm G, formed of copper or other suitable material, dividing the same
with a steam-tight joint, as shewn in Fig. 1. The compartment A' is fitted with a
safety valve a, lever d, and adjustable weight f. This safety valve is fitted in a box b,
having a pipe t fitted so as to carry escaping steam.to the ash-pit, where its presence
will damp the fire and reduce the combustion, and also warn the attendant that the
working pressure has been exceeded.

page_text: The compartment A' is fitted with a small external glass pane K, held in position
by a flange M, screwed to the plate P.
A central hole S is formed in the plate and a boss R is provided which acts as a
guide to the piston and piston rod I. The piston rod is supported in the socket H,
the end of which is formed with four, or any other number of teeth D D, which just
touch the diaphragm G. The piston I just clears the diaphragm, and the end of the
piston rod, next to the glass K, is formed with a sharp point. The pipe O is open to
the atmosphere, and is made sufficiently large to carry off any excess of steam that
may be produced.
The area and thickness of the diaphragm G are so arranged that it yields to an
excess of pressure; and when the intended pressure is exceeded, the diaphragm G is
pressed against the teeth D which pass through the plate, forming perforations through
which steam escapes; the plate & being buckled or bulged by the pressure, then
presses the piston I, the pointed rod of which breaks the glass pane K, thus giving
warning that the pressure in the generator has exceeded the requisite limit.
When it is desired to provide further means for giving warning of danger, it can be
obtained by means of any suitable arrangement or contrivance, placed in close
proximity to the glass pane K and in front of the piston rod I, whereby the latter
will effect contact with such contrivance, and such contact may, either by electricity
or otherwise, be utilised to afford an additional signal or warning.
The several parts of the apparatus are so proportioned that ample means are afforded
to permit the surplus steam to escape, and lower the pressure in the boiler.
Dated the 20th Santambar 1886
I, GEORGE DOWNING, of 8 Quality Court, Chancery Lane, in the County of
Middlesex, Patent Agent, do hereby declare the nature of my said invention and in
what manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :-
The fundamental principle upon which my invention is based is the application to
steam generators of a diaphragm constituting a weak point, offering less resistance to
the pressure of the steam than the ordinary plates of the generator; so that in case of
an excess of pressure within the generator, this diaphragm consisting of a thin metallic
plate, glass membrane, or other suitable material may yield to an excess of pressure and
allow the escape of the contents of the boiler, thus preventing an explosion. My
apparatus also acts automatically, in case of a more or less considerable excess of
pressure so as to give an alarm with the aid of a whistle or other suitable, device, or
the lowering or complete extinction of the fire in the firebox or furnace by means of
an injection of steam, or of water into the ashbox, or in the firebox or furnace,

page_text: And in order that my said invention may be more particularly described and ascer-
tained, reference is hereby made to the accompanying drawings in which similar
letters of reference indicate corresponding parts.
Fig. 1 is a sectional elevation of the apparatus.
Fig. 2 is a horizontal section shewing the method of fixing the cutting plates K.
Fig. 3 shews the form of one of the cutting plates K.
Upon the steam generator and above or below the water level is bolted or otherwise
fixed a short pipe ✗ open to the generator through B. Upon this pipe is placed a
plate A of thin copper or any other suitable material forming a joint. Above this
diaphragm is placed another short tube C of similar section to the tube X. Within
the sleeve C are formed four longitudinal grooves D arranged as shewn in Fig. 2 at
the extremities of two perpendicular diameters. These grooves are designed to guide
and maintain the cutting blades K placed in the form of a cross. The blades, as
shewn in Fig. 3 have their sharp edges notched either in the manner shewn in the
drawing, or as a saw, or in any other suitable manner, according to the rapidity with
which they are intended to act. When the blades are placed in position upon the
tube C, a second tube similar to the former minus the grooves is fitted. The
chamber is provided to receive the steam after the rupture of the plate A, from
whence it escapes through the alarm whistle S, and through the pipe Z, leading to
the ashbox. The tube or cylinder c¹ also retains the cutters K in position upon or
against the plate A. Above the tube c¹ I place a second plate of thin metal A¹, and
above the latter a third tube c² formed and fitted in a similar manner to the tube c'
with cutters K¹ surmounted by an escape tube Y. To the pipe X I fit a pipe T,
leading to the lower part of a valve I, which is held down by a lever L provided
with a screw thread and wheel P, the wheel P acting as a counterweight. This lever
is graduated so that by placing the counterweight at suitable points, the lifting takes
place at certain pressures. For instance, the counterweight being upon the third
division, the valve will act as soon as the pressure in the boiler reaches three atino-
spheres and so forth. The chamber of this valve U is connected by a pipe Q to the
ash box of the boiler, so that, when entering therein, the steam reduces the combustion,
by arresting the draught. This arrangement allows the fireman to leave his boiler
for short periods without fear of explosion. The apparatus operates in the following
manner :- -When the pressure causes the rupture of the plate A, the steam enters the
chamber O from whence it acts upon and sounds the alarm whistle S, while compressing
the plate A¹ upon the cutters K. Steam escapes at the same time through the
pipe Z leading to the ash pan of the generator, and reduces combustion, and therefore
also the production of steam. If at this time the pressure continues to increase and
exceeds the resistance of the two plates, the plate A' is ruptured, and the boiler is
immediately eased of pressure. In order to avoid the overheating of the metal of the
firebox or furnace, which would occur if, subsequently to the boiler being emptied
no person were present to draw the fire, I cause the fire to be extinguished by injecting
hot water thereon taken from the boiler, or cold water taken from a pipe, placed in
proximity. To obtain this result I fit the boiler below the water level with a pipe M,
leading to the fire box or furnace and closed by a cock E, this cock being placed near
the side of the boiler. The rod e is connected by a chain n to a lever Farranged
horizontally upon the axis of a half butterfly valve G placed in the upper tube Y as
shewn in Fig. 1. When the rupture of the second plate k takes place it causes the
valve G to rise from a horizontal to a vertical position raising the lever F¹ and the
chain attached to the small crank F¹ thereby opening the cock E, the water then
escapes through the pipe M. and extinguishes the fire.
In horizontal boilers I substitute a rod for the chain n.
Having now particularly described and ascertained the nature of my said invention,
and in what manner the same is to be performed, I declare that what I claim is :—
1. The application to steam generators of plates, membranes, or other suitable
materials subjected to the full pressure of the steam which are intended to give way
or become broken or ruptured upon a considerable increase of pressure taking place,

page_text: and thereby prevent explosion, substantially as hereinbefore described and illustrated
on the drawings.
2. In apparatus of the description and for the purpose aforesaid, the use of a
metallic or other plate A subjected on one side to the pressure of the steam, and held
in position by cutting plates K, whereby it may be perforated or ruptured from
increased pressure substantially as heroinbefore described and shewn on the drawings.
3. In apparatus as aforesaid, the application and use of cutting plates K K, for
opening or destroying the diaphragin A, when exposed to excessive pressure,
substantially as herein before described and shewn on the drawings.
4. In apparatus as aforesaid, the application and use of several diaphragms or metallic
plates A A having similar or various powers of resistance, so fitted that they may
yield or burst under the influence of pressures of various intensities substantially as
herein before described and shewn on the drawings.
5. In apparatus as aforesaid, the application and use of a chamber arranged
between two diaphragms A and A¹ in communication with an alarm whistle S (and
with a pipe Z leading to the ash box of the generator) so that after the rupture of the
first plate A, the steam, when escaping, causes the whistle to operate on the one
hand and passes through the pipe Z, on the other hand being subsequently injected
in the ash box where it diminishes the draught and reduces combustion.
6. In apparatus as aforesaid, the application and use of a half butterfly valve G,
mounted upon a spindle and arranged so as to be capable, under the pressure of the
escaping steam and, after the rupture of the diaphragm A', of turning a lever arm F
and opening the cock E, for the purpose of causing water to be injected into the
fire box or furnace, substantially as hereinbefore described and shewn on the
drawings.
7. In apparatus as aforesaid, the application and use of the valve J, in combination
with a graduated lever L carrying a movable wheel P, arranged so that to a regulated
pressure according to the position of the wheel P upon the lever L, the steam from
the generator may actuate the valve J, and pass through a pipe Q, leading to the
ash box of the generator and thus reduce the rate of combustion, substantially as
hereinbefore described and shewn on the drawings.
8. The general construction, combination and arrangement of the several and
respective parts together constituting my invention of an improved safety apparatus
for steam generators substantially as hereinbefore described and shewn on the
drawings.
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