IMPROVEMENTS IN FUSIBLE PLUGS FOR STEAM GENERATORS
Year: 1881

page_text: LETTERS PATENT to Henry Adams, of Queen Victoria Street, in the City of
London, Civil and Mechanical Engineer, for an Invention of "IMPROVEMENTS
IN FUSIBLE PLUGS FOR STEAM GENERATORS."
PROVISIONAL SPECIFICATION left by the said Henry Adams at the Office
of the Commissioners of Patents on the 13th April 1881.
HENRY ADAMS, of Queen Victoria Street, in the City of London, Civil
and Mechanical Engineer. " IMPROVEMENTS IN FUSIBLE PLUGS FOR STEAM
GENERATORS."
My Invention is designed to render fusible plugs as used in boilers or other
steam generators or furnaces for protection against shortness of water or over-
heating more durable and reliable.
To effect this I construct my improved fusible plug with a coned summit inside
the boiler or generator of sufficient steep pitch to prevent sediment resting upon it.
I further protect the fusible metal from direct contact with the hot gases of the
fire, so that no oxidation or deterioration of the fusible metal can take place, and
it is thus always in a proper condition for action and fusing when the heat becomes
excessive.
My plug may be made either for screwing into the shell of the fire box from the
inside of the fire box, or for fixing from the interior of the boiler or generator.
In the first case my plug consists essentially of two distinct parts, viz., that
which screws into the fire box shell, and a central coned piece fixed into the orifice
of the lower piece by a surrounding band or ring of the fusible metal which is
swelled or recessed into either or both parts of the plug. The lower part of this
interior coned plug nearly fits the orifice of the exterior screwed part, so that the
fusible metal above is protected from the action of the flame or gases. The exterior
portion of the combined parts of the plug projecting into the interior of the generator
is turned smoothly conical to a steep pitch.
In the latter case my plug is formed of three separate parts, viz. :-
First. That which screws into the shell of the fire box provided with an

page_text: hexagonal collar that prevents any possibility of the plug being blown through
the fire box.
Secondly. The exterior part of the coned plug which screws on to the part first
described, and
Thirdly. The central coned plug fixed into the external part by a circular ring
of fusible metal swelled or recessed into either or both parts of the plug.
In this latter case the whole cap or plug can be removed or renewed without
disturbing the seating in the fire-box crown.
By my method of construction, as before described, the opening for the escape
of steam may be made exceptionally large.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Henry Adams in the Great Seal Patent Office on the 12th October
1881.
HENRY ADAMS, of Queen Victoria Street, in the City of London, Civil
and Mechanical Engineer. "IMPROVEMENTS IN FUSIBLE PLUGS FOR STEAM
GENERATORS."
My Invention is designed to render fusible plugs as used in boilers or other
steam generators or furnaces for protection against shortness of water or over-
heating more durable and reliable.
To effect this I construct my improved fusible plug with a coned summit inside
the boiler or generator of sufficient steep pitch to prevent sediment resting upon
it. I further protect the fusible metal from direct contact with the hot gases of
the fire, so that no oxidation or deterioration of the fusible metal can take place,
and it is thus always in a proper condition for action and fusing when the heat
becomes excessive.
My plug may be made either for screwing into the shell of the fire box from the
inside of the fire box, or for fixing from the interior of the boiler or generator. In
the first case my plug consists essentially of two distinct parts, viz., that which
screws into the fire box shell, and a central coned piece fixed into the orifice of the
lower piece by a surrounding band or ring of the fusible metal, which is swelled or
recessed into either or both parts of the plug. The lower part of this interior
coned plug nearly fits the orifice of the exterior screwed part, so that the fusible
metal above is protected from the action of the flames or gases. The exterior
portion of the combined parts of the plug projecting into the interior of the generator
is turned smoothly conical to a steep pitch.
In the latter case my plug is formed of three separate parts, namely, first, that
which screws into the shell of the fire box provided with an hexagonal or other
suitable collar that prevents any probability of the plug being blown into the fire
box.
Secondly, the exterior part of the coned plug which screws on to the part first
described.
And, thirdly, the central coned plug fixed into the external part by a circular
ring of fusible metal swelled or recessed into either or both parts of the plug. In
this latter case the whole cap or plug can be removed or renewed without disturbing
the seating in the fire box crown.
By my method of construction, as before described, the opening for the escape of
steam may be made exceptionally large.
And in order that my Invention may be better understood, I now proceed to
describe the Drawings hereunto annexed, reference being had to the letters and
figures marked thereon. Like letters refer to like parts in each of the figures.
Figs. 1, 2, and 3 show an outside elevation, sectional elevation, and plan of my
plug as suited for screwing into the crown of a fire box from the interior. The
plug is made essentially of two parts, A and B, of which the outer part A is screwed
at a, for fixing into the fire box shell. There is a hexagonal or otherwise conveniently
formed head C provided for screwing the plug into the fire box shell.
The inner portion of the plug B is independent of the outer part A, and is held
in position by the fusible metal D. This metal may be run in from the circular
channel d, as shewn in the one half elevation, or may be run in through the hole d',
s shewn in the other half elevation. By these arrangements the fusible metal is
almost entirely covered and protected from oxidation by the action of the flame or

page_text: other deterioration. The upper end of the portion C is turned smoothly conical
to a steep pitch to prevent the adherence of sediment.
In Figs. 4, 5, and 6, a plan, sectional elevation, and outside elevation of my
modified plug is shown. The plug in this case consists of three parts, E, F, and G.
The part E is screwed at each end and provided with a hexagonal or otherwise
suitably shaped collar at the centre. By means of this collar the piece E can be
screwed from above into the fire-box shell, and there remain a fixture upon or from
which the other portions of the plug F and G can be screwed or removed at will
for repair or replacement. The portions F and G are independent as before, and
are held together by the fusible metal H, which is run into the recess turned partly
out of each portion.
The fusible metal may be poured in through the circular channel h, as shown
in one half elevation, or through the hole h', as shown in the other half elevation,
so that the metal is thus nearly covered and protected from oxidation and deteriora-
tion by the action of the flames. The same smooth conicity of the upper part G is
used, as before, at a steep pitch to throw off sediment.
And now having fully described and ascertained the nature and object of my
Invention, and the manner in which the same is performed, be it known that what
I consider novel and useful, and desire to protect by my Letters Patent is,—
1st. The combination in a fusible plug of an inner and outer part, by means of a
ring of fusible metal recessed or swelled into either or both parts,
2nd. In a fusible plug the approximate contact of a shoulder of the inner
portion of the plug with the outer plug under the fusible metal to protect it from
the heat.
3rd. In a fusible plug the steep conical pointed-form of the plug to prevent
deposit of sediment upon it.
In witness whereof, I, the said Henry Adams, have hereunto set my hand
and seal, this Sixth day of October, in the year of our Lord One thousand
eight hundred and eighty one.
In the presence of
S. P. WILDING,
23, Rood Lane,
London, E.C.,
Patent Agent.
HENRY ADAMS.
(L.S.)