AN IMPROVED SAFETY APPARATUS FOR PREVENTING EXPLOSIONS IN STEAM BOILERS
Year: 1875

page_text: LETTERS PATENT to Jules Armengaud, jeune, of Paris, Boulevard
de Strasbourg, No. 23, Civil Engineer, for the Invention of "AN
IMPROVED SAFETY APPARATUS FOR PREVENTING EXPLOSIONS IN STEAM
BOILERS." A communication by Jacques Marcel Cornevin, of
Montluçon (France), Engineer.
PROVISIONAL SPECIFICATION left by the said Jules Armengaud at
the Office of the Commissioners of Patents, with his Petition, on
the 10th June 1875.
I, JULES ARMENGAUD, jeune, of Paris, Boulevard de Strasbourg,
No. 23, Civil Engineer, do hereby declare the nature of the said In-
vention for "AN IMPROVED SAFETY APPARATUS FOR PREVENTING EXPLOSIONS IN
STEAM BOILERS," (communicated to me by Jacques Marcel Cornevin, of
Montluçon (France,) Engineer,) to be as follows:-
The apparatus which forms the subject of the following description,
and which is called the "non-exploder" against failure of water, has for

page_text: its object to entirely prevent the explosion occasioned by the failure of
water in closed steam boilers.
The safety apparatus prescribed and recommended by the existing
regulations are without direct action, and insufficient to prevent
explosions occasioned by a failure in the supply of water, the most
frequent and disastrous of all the causes of accident.
The "non-exploder" contrived by the present Inventor to supply the
want which has just been pointed out is without mechanism and of a
most simple construction, and therefore has a perfectly certain action.
The principle of its action consists in causing the failure of water to
take place at one point only of the heated surface in order to cause the
opening of an exit through which the water can escape; by its escape
into the furnace the steam demonstrates the situation and prevents the
continuation of the heating before the level of the water can descend
beneath the point which it must not be allowed to pass. The non-
exploder is placed in the interior of the boiler at a point near to the
furnace. It is composed of a short reservoir of circular form attached by
a bracket and bolts so as to join it with the circumference of a curved
opening made at the desired point in the side of the boiler. The part
forming the reservoir traverses this opening, closing it so as to project to
the exterior part of the boiler. This projecting part of the reservoir
has its bottom formed for the greater part of a washer of the same
metal of which the circumference is trunk conically shaped, adapting
itself exactly in the opening which is of the same form similar to a
reversed valve. A plug or washer is soldered with tin throughout its
surface in contact with that of the side of the reservoir in order to
form but one bottom with which its curves unite. This arrangement
of the piece placed like a reversed valve and soldered with tin can
be replaced by the following arrangement which has the same result,
but which dispenses with actual soldering. In the latter case the
piece is placed like an ordinary valve, that is to say, the larger diameter
of its cone is placed above instead of being below. The opening where
this washer is placed is sufficiently great to allow it to pass freely; from
which there results a play between the cones of the piece and the
reservoir. This play is limited by a ring of exactly the same form.
This ring is first squeezed by the washer, upon which it supports at
three points the cover, to be mentioned presently, then also by the
pressure of the steam which acts in this case as an autoclave.

page_text: In the interior of the boiler the reservoir is closed by a removable
cover in the form of a reversed hat pressed at its centre by a screw
depending from a cross piece passed at each end into an ear piece formed
in the reservoir. The edge of this cover is supported by a neck lined
with india-rubber or other flexible material so as to form a stanch joint.
The cover is removable in order to permit the interior of the reservoir to
be easily got at so as to permit of cleaning when that is necessary, and
of the putting in place again of the washer when it has been expelled
through the failure of water. Each side of the reservoir is provided
with a little tube continued by a pipe, one end of which is raised a little
higher than the other end, the shorter only rising to the point below.
which the level of the water must not pass. These two pipes are
provided with roses to arrest foreign bodies which might stop them up.
The tubes debouch in the interior of the reservoir, which thus puts the
two pipes in communication with it.
The conditions under which the non-exploder remains at rest, and
under which it is called into action are as follows:-The boiler being
fitted with water to its normal level the non-exploder is completely sub-
merged and filled with water drawn through the pipes beneath the
water. The boiler being put in action all its heating surface vaporizes.
The bottom of the non-exploder, forming a part of the heating surface,
vapourizes also in proportion to its surface. The steam produced is led
off through the pipe which is the largest, and with its opening the most
elevated in the reservoir. In proportion as the water contained in the
reservoir vapourizes it is naturally replaced by other water which
descends through the pipe which is the shortest, and with its opening
the lowest in the reservoir. So long as the level of the water in the
boiler does not lower sufficiently to uncover the end of the pipe things
remain as they were, and non-exploder should not and cannot act.
If from any cause the normal level of the water is not maintained
within the boiler and it lowers so far as to expose the end of the pipe,
water cannot be led by this pipe or any other into the reservoir, which
thus ceases to be fed. This interruption of the feeding of the reservoir
brings about with fatal speed the failure of water, which never ceases
from being heated and being formed into steam so as to rapidly exhaust
the little water remaining in the boiler.
Starting from the moment when the water fails in the non-exploder,
its lower bottom which continues to be heated acquires a more elevated

page_text: temperature than that covered by the water. This temperature rapidly
rises to such a point that the tin solder at the points or the tin washer
softens and becomes, if maintained, the washer upon which the pressure
of steam is exerted in place, and it follows that this washer is expelled
from its place so that the steam aloné rushes into the two pipes to
proceed violently through the opening just produced, and enters the
furnace with a great noise.
From the moment when the washer is expelled, warning is given first
by the continuous noise caused by the escaping steam, and then by the
impossibility of continuing the heating, which is paralysed by the arrival 1
of the steam in the furnace and into the flues in which the heated gases
circulate. The heating is then forcibly arrested.
'
During the period preceding the failure of water in the reservoir, a
period of short duration, at the end of which the forcible stoppage takes
place, the level of the water within the boiler has lowered but little 1
beyond the lowest normal level; and explosion of steam cannot take
place in consequence of the failure of the water supply; all accidents
from this cause are consequently avoided and prevented, and the non-
exploder has fulfilled its object.
This safety apparatus is applicable to all boilers, as well to vertical as 2
to horizontal boilers; it is only a question of form and dimension for
the type of boiler to which it is to be applied. The principle of the
apparatus remains the same in all cases; in vertical boilers it is placed
against the vertical side close to the furnace or heating body, as in hori-
zontal ones. In elephant boilers (Chandieres à bouilleurs) it is also 24
placed closed to the fire, but if the heating surface is beneath the
separate boiler bodies, instead of being under the cylindrical body the
pipes must pass through the communicating tubes connecting the
separate boiler bodies, so that their ends can occupy the position
prescribed as the lowest normal level of the water with the boiler.
30

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Jules Armengaud in the Great Seal Patent Office
on the 10th December 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JULES
ARMENGAUD, jeune, of Paris, Boulevard de Strasbourg, No. 23, Civil
Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Tenth day of June, in the year of our
Lord One thousand eight hundred and seventy-five, in the thirty-eighth
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto me, the said Jules Armengaud, jeune, Her special license
that I, the said Jules Armengaud, jeune, my executors, administrators,
and assigns, or such others as I, the said Jules Armengaud, jeune, 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 "AN IMPROVED
SAFETY APPARATUS FOR PREVENTING EXPLOSIONS IN STEAM BOILERS," (com-
municated to me by Jacques Marcel Carnevin, of Montluçon, France,
Engineer), upon the condition (amongst others) that I, the said Jules
Armengaud, jeune, 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 Jules Armengaud, jeune, do
hereby declare the nature of the said Invention, and in what manner
the same is to be performed, to be particularly described and ascertained
in and by the following statement thereof, that is to say :—
The apparatus which forms the subject of the following description,
and which is called the "non-exploder" against failure of water, has for
its object to entirely prevent the explosions occasioned by the failure of
water in closed steam boilers.

page_text: The safety apparatus prescribed and recommended by the existing
regulations are without direct action, and insufficient to prevent
explosions occasioned by a failure in the supply of water, the most
frequent and disastrous of all the causes of accidents.
The "non-exploder" contrived by the present Inventor to supply the
want which has just been pointed out is without mechanism and of a
most simple construction, and therefore has a perfectly certain action.
The principle of its action consists in causing the failure of water to take
place at one point only of the heated surface, in order to cause the
opening of an exit through which the water can escape. By its escape
into the furnace the steam demonstrates the situation and prevents the
continuation of the heating before the level of the water can descend
beneath the point which it must not be allowed to pass. The non-
exploder is placed in the interior of the boiler at a point near to the
furnace. The explanatory Drawings annexed hereto shows it in section
and in plan placed within a cylindrical boiler. It is composed of a short
reservoir a of circular form attached by a bracket 6 and bolts c so as to
join with the circumference of a curved opening d made at the desired
point in the bottom side r of the boiler. The part a forming the
reservoir traverses this opening, closing it so as to project to the exterior
part of the boiler. This projecting part of the reservoir has its bottom e
formed for the greater part by the washer g of the same metal of which
the circumference h, h', is made, and is conically shaped, adapting itself
exactly in the opening which is of the same form, similar to a reversed
valve. The plug or washer g is soldered with tin throughout its surface
in contact with that of the side of the reservoir a, in order to form but
one bottom e with which its curves unite. This arrangement of the
piece g placed like a reversed valve and soldered with tin can be replaced
by the following arrangement which has the same result, but which
dispenses with actual soldering. In the latter case the piece g is placed
like an ordinary valve, that is to say, the larger diameter of its cone is
placed above instead of being below. The opening where this washer is
placed (see the partial section, Figure 3, and the sectional plan,
Figure 4), is sufficiently great to allow it to pass freely, from which
there results a play between the cones of the piece g and the reservoir a.
This play is limited by a ring t, t, of exactly the same form. This
ring is first squeezed by the washer 9, upon which it supports at three
points 8, 8, the cover j, to be mentioned presently, then also by the
pressure of the steam, which acts in this case as an autoclave.

page_text: In the interior of the boiler the reservoir a is closed by a removable
cover j in the form of a reversed hat pressed at its centre by a screw k
depending from a cross piece 6 formed at each end into an ear piece m
formed in the reservoir a. The edge of the cover j is supported by a
neck n lined with india-rubber or other flexible material, so as to form a
stanch joint. The cover j is removable in order to permit the interior
of the reservoir to be easily got at, so as to permit of cleansing when
g when
that is necessary, and of the putting in place again of the washer
it has been expelled through the failure of water. Each side of the
reservoir a is provided with a little tube p, p¹, continued by a pipe, one
end of which q is raised a little higher than the other end q¹, the latter
only rising to the point below which the level of the water must not
pass. These two pipes are provided with roses to arrest foreign bodies
which might stop them up. The tubes p, p¹, debouch into the interior
of the reservoir a, which thus puts the two pipes q, q', in communication
with it.
The conditions under which the non-exploder remains at rest and
under which it is called into action are as follows:-The boiler being
filled with water to its normal level the non-exploder is completely
submerged and filled with water drawn through the pipes q, q', beneath
the water. The boiler being put in action all its heating surface
vapourizes. The bottom e of the non-exploder forming a part of the
heating surface vapourizes also in proportion to its surface. The steam
produced is lead off through the pipe q which is the longest, and with
its opening most elevated in the reservoir a.
In proportion as the water
contained in the reservoir vapourizes it is naturally replaced by the
water which descends through the pipe q¹ which is the shortest, and
with its opening the lowest in the reservoir. So long as the level of the
water in the boiler does not lower sufficiently to uncover the end of the
pipe q¹ things remain as they were, and the non-exploder should not and
cannot act.
If from any cause the normal level of the water is not maintained
within the boiler, and it lowers as far as to expose the end of the pipe q',
water cannot be led by this pipe or any other into the reservoir which
thus ceases to be fed. This interruption of the feeding of the reservoir a
brings about with fatal speed the failure of water, which never ceases
from being heated and being formed into steam so as to rapidly exhaust
the little water remaining in the boiler.

page_text: It should be remarked that the water failing in the reservoir a the
level of the water in the boiler is lowered but little, because the relation
of the volume of water in the reservoir to its heating surface is much
less than that of the boiler to its heating surface.
Starting from the moment when the water fails in the non-exploder
its lower bottom e which continues to be heated acquires a more elevated
temperature than that covered by the water. This temperature rapidly
rises to such a point that the tin solder at the points h, h¹, or the tin
washer t, t, softens and becomes incapable to hold in its place the
washer g, upon which the pressure of steam is exerted, and it follows
that the washer is expelled, so that the steam rushes into the two
pipes q, q', and proceeding violently through the opening just produced
enters the furnace with a great noise.
From the moment when the washer 9 is expelled warning is given,
first, by the continuous noise caused by the escaping steam, and then by 1
the impossibility of continuing the heating, which is paralized by the
arrival of the steam in the furnace and the flues in which the heated
gases circulate; the heating is then forcibly arrested.
During the period preceding the failure of water in the reservoir,
a period of short duration, at the end of which the forcible stoppage 2
takes place, the level of the water within the boiler has lowered but
little beyond the lowest normal level, and explosion of steam cannot
take place in consequence of the failure of the water supply. All
accidents from this cause are consequently avoided and prevented, and
the non-exploder has fulfilled its object.
2
The safety apparatus is applicable to all boilers, as well to vertical as
to horizontal boilers; it is only a question of the form and dimension
for the type of boiler to which it is to be applied. The principle of the
apparatus remains the same in all cases. In vertical boilers it is placed
against the vertical side, close to the furnace or heating body, as in 3
horizontal ones. In usual boilers it is also placed close to the fire, but
if the heating surface is beneath the separate boiler bodies instead of
being under the cylindrical body the pipes q, q', must pass through the
communicating tubes connecting the separated boiler bodies, so that
their ends can occupy the position prescribed as the lowest normal level 3
of the water within the boiler.

page_text: And having now described the nature of the said Invention, and in
what manner the same is to be performed, I declare that I claim,-
First. The improved safety apparatus for preventing explosions in
steam boilers, substantially as herein-before described and shown in the
accompanying Drawings.
And, Secondly. The use of a plug or washer 9, soldered as herein-
before explained, for the purposes herein-before described and shown.
In witness whereof, I, the said Jules Armengaud, have hercunto set
my hand and seal, this Twenty-sixth day of November, One
One thousand eight hundred and seventy-five.
JULES ARMENGAUD. (L.S.)
Witness,
CHARLES FROSSARD,
23, Boulevard de Strasbourg.