IMPROVEMENTS IN FUSIBLE PLUGS FOR STEAM BOILERS
Year: 1879

page_text: LETTERS PATENT to George Platts and Frank Wood, both of Salford, in
the County of Lancaster, for the Invention of "IMPROVEMENTS IN FUSIBLE
PLUGS FOR STEAM BOILERS."
Sealed the 3rd February 1880, and dated the 12th November 1879.
PROVISIONAL SPECIFICATION left by the said George Platts and Frank
Wood at the Office of the Commissioners of Patents on the 12th November
1879.
GEORGE PLATTS and FRANK WOOD, both of Salford, in the County of Lancaster.
"IMPROVEMENTS IN FUSIBLE PLUGS FOR STEAM BOILERS."
These improvements refer to that description of Smith's fusible plug in which
two cones are employed, the outer cone being screwed or otherwise secured in and,
by preference, over the crown of the boiler furnace, whilst the inner cone is secured
in position inside the outer cone by an intermediate layer of fusible metal, and so
as to be capable of being blown out bodily, as is well understood.
Now these improvements consist in making the outer cone (which contains the
inner cone secured therein in the ordinary manner) separate from the base or
screwed portion, which is secured as usual to the boiler crown or other part, and in
arranging such outer cone or its equivalent to screw by means of a left handed
screw thread into the base or screwed portion, hereinbefore described, from the
inner side by means of a T headed or other suitable key, a water tight joint being
effected by the lower part of such outer cone or its equivalent being formed to
screw against a corresponding tapered surface formed inside the screwed base in
front of the female screw.
In this manner I am enabled without entering inside the boiler to remove the
outer cone or its equivalent bodily, and thus to replace the inner cone and fusible
portion, or to substitute a corresponding outer cone.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said George Platts and Frank Wood in the Great Seal Patent Office on
the 11th May 1880.
<<
GEORGE PLATTS and FRANK WOOD, both of Salford, in the County of Lancaster.
"IMPROVEMENTS IN FUSIBLE PLUGS FOR STEAM BOILERS."
These improvements refer to that description of Smith's fusible plug in which
two cones are employed, the outer cone being screwed or otherwise secured in and,
by preference, over the crown of the boiler furnace, whilst the inner cone is secured
in position inside the outer cone by an intermediate layer of fusible metal and so
as to be capable of being blown out bodily, as is well understood.
Now these improvements consist in making the outer cone (which contains the
inner cone secured therein in the ordinary manner) separate from the base or
screwed portion, which is secured as usual to the boiler crown or other part, and in
arranging such outer cone or its equivalent in combination with a screw to screw
by means of a left handed screw thread into the base or screwed portion, berein-
before described, from the inner side by means of a T headed or other suitable key,
a water-tight joint being effected by the lower part of such outer cone or its
equivalent being formed to screw against a corresponding tapered surface formed
inside the screwed base immediately in front of the female screw.
And in order that this our said Invention may be the more readily understood
and carried into practical effect, we have hereunto annexed a Drawing illustrative
of our improved Smith's fusible plug, and will now proceed to describe the
same, reference being had to the letters of reference marked thereon, which denote
similar parts in all the views.
Figure 1 is an exterior view, Figure 2 a sectional view, Figure 3 a top view
or plan, and Figure 4 an inverted plan of our improved fusible plug.
A is the base or screwed portion of the plug, which is secured as usual to the
boiler crown B or other desired part of the boiler; C is the outer cone which, in
accordance with this Invention, is constructed all in one piece with the screwed
tail piece D, the screw of such tail piece being by preference a left handed screw
thread, which screws, into the corresponding female thread formed inside the base A,
as illustrated. This outer cone C contains an inner cone C¹ secured in position by
the intervening fusible metal E in the ordinary manner. A water tight joint is
effected between the outer cone C and the base A by arranging the former at the
part marked G immediately in front of the screw thread D of a tapered form and
grinding the same in course of manufacture into the correspondingly tapered orifice
formed through the upper part of the base A.
The outer cone is thus capable of being withdrawn from the base by being
unscrewed from the inside of the flue or furnace, a pair of recesses H being arranged
inside such cone to receive a T headed or box key, by means of which the screwing
and unscrewing operations are performed. In this manner we are enabled without
entering the boiler to remove the outer cone or its equivalent bodily and thus
to replace the inner cone and fusible portion, or to substitute a corresponding
outer cone.
Having thus particularly described and ascertained the nature of this our said
Invention, together with the best methods with which we are acquainted for
carrying the same into practical effect, we wish it to be understood that we are
aware that a loose outer cone provided with a flanch has hitherto been applied to a
fusible plug and secured in position by a separate nut or screwed annular ring,
and therefore we make no claim to such parts when so constructed and used
separately, but what we do claim is,--
Constructing fusible plugs with the outer cone in combination or all in one piece

page_text: with the screw employed for securing the same in position in the base or other
portion, and effecting the necessary water tight joint between the parts, sub-
stantially as herein before described and illustrated on the accompanying
Drawing.
In witness whereof, I, the said George Platts, for and on behalf of myself
and the said Frank Wood, have hereunto set my hand and seal, this
Tenth day of May, in the year of our Lord 1880.
GEORGE PLATTS. (L.S.)