Year: 1888

page_text: Date of Application, 26th Jan., 1888
Complete Specification Left, 26th Nov., 1888
Complete Specification Accepted, 31st Dec., 1888
I HOWARD FIELD The Bank Southall Middlesex Engineer do hereby declare the
nature of this invention to be as follows
--
My Invention consists in the use of a piece of fusible metal tube which I fit round
a tapered plug and into a tapered seat in the following manner.
I make a tapered plug of such a size that it will just pass through a similarly
tapered hole or seat which I require to plug. Through this tapered plug I tap a
hole to receive a screw. I then take a suitable length of fusible metal tubing of
such a size externally that it will just pass through the seat and of such a size
internally that it will just allow the smaller end of the tapered plug to enter. I
pass a screw through this piece of tube and screw it into the small end of the
tapered plug until the head of the screw, which I make rather larger than the
tube so that it shall not pass through, presses upon the one end of the tube and
the smaller end of the tapered plug just enters the other end of the tube. I then
pass the plug, so prepared, through the tapered seat, from the smaller side, until
it is prevented going further by the head of the screw, which is too large to pass
through.
By now turning the screw I draw the tapered plug into the fusible
metal tube which expands as the tube enters until it fills the seat and forms a fusible
ring between the plug and its seat. It is obvious that if this ring melts, through
any cause, the plug will fall through the seat and allow a clear passage for the
steam to issue.
1000

page_text: COMPLETE SPECIFICATION,
Fusible Plug for Steam Boilers.
1, HOWARD FIELD, of the Bank, Southall, in the County of Middlesex, Engineer,
do hereby declare the nature of this invention and in what manner the same
is to be performed to be particularly described and ascertained in and by the
following statement :-
My invention consists in the use of a piece of fusible metal tube adapted to fit
between a cone and a tapered seat in the following manner :-
The cone is made of such a diameter that it will just pass through the hole or
passage in the seat which it is required to plug. This hole or passage is tapered
to correspond with the conc. In the cone is tapped a hole to receive a hand screw.
This hand screw is first passed through a suitable length of fusible metal tube, of
such an external diameter that it will just pass through the hole or passage in
the seat, and of such an internal diameter that it will just allow the smaller end
of the cone to enter it, and it is then screwed into the small end of the cone until
the head of the screw, or a washer thereon, which is made rather larger than the
fusible tube so that it shall not pass through it, or through the hole or passage in
the seat presses upon the one end of the said tube and the smaller end of the
tapered plug just enters the other end of the tube. The plug, so prepared, is then
passed through the tapered hole or passage of the seat, from the smaller side, until
it is prevented going further by the head or collar of the hand screw, which is too
large to pass through it. By turning the hand screw the cone is drawn into the
fusible metal tube which expands as the cone enters, until it fills the seat and
forms a fusible ring between the cone and its seat. It is obvious that if this ring
melts, through any cause, the cone will fall through the seat and allow a clear
passage for the steam to issue.
In order that my invention may be fully understood I herewith append a drawing
which illustrates it. Figure 1. is a view in cross section showing my improved fusible
plug as it is passed through its seat prior to its being fixed. Figure 2. is a view in
cross section of the cone "seated," and Figure 3. is a view in plan of the cone and its
seat. Throughout these views similar parts are marked with like letters of reference.
In any suitable form of seat A. adapted to be screwed into, or otherwise fixed to,
the boiler plate X, is formed a circular hole or passage in which is
formed a shoulder a. making the hole or passage coned or taper from the top
edge. A cone B. tapered to coincide with the tapered hole in the seat A. is
provided with a hole b. threaded to receive the screwed end c. of the hand
Screw C. On this hand screw is loosely mounted a collar c¹ of a diameter large enough
to abut against the shoulder a. in the seat A. After a short length of fusible metal
tube D. is passed over the screwed end c. of the hand screw, the cone B. is screwed
thereon until the taper end of the cone just enters the end of the fusible tube which
rests on the collar c¹ of the hand screw. In this position the hand screw with the
fusible tube and the cone is passed through the seating A. from the inner side thereof
as illustrated by Figure 1. of the accompanying drawing, the greatest diameter of the

page_text: cone B. and that of the fusible tube D. being such that they will just pass through th
smallest diameter of the seat A. After the hand screw is placed in the position illus-
trated by Figure 1. of the accompanying drawing it is turned round to draw the
cone B. down into the seat, expanding the fusible tube D., and forming a fusible ring
between the cone B. and the seat A. when it is jambed tightly down into the position
illustrated by Figure 2. of the accompanying drawing. The necessary frictional
resistance between the cone B., fusible tube D., and seat A. to ensure the hand screw
drawing the plug down, is obtained by means of the loose collar c' on the hand
screw
It will be obvious that when the fusible metal ring D. melts, the cone B. will drop
through the seat A. and allow a clear passage for the steam to issue.
It will be seen that by my invention a fusible plug can be "seated" from the interior
of the furnace or flue, without having to gain access to the interior of the boiler.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1st. A fusible plug for steam boilers, constructed, arranged, and operating, as set
forth.
2nd. In a fusible plug for steam boilers, the combination of the seat A. having a
coned or taper hole or passage therethrough, the taper cone B adapted to pass freely
through the passage in the seat A, the fusible metal tube or ring D., adapted to pass
freely through the passage in the seat A and to be expanded by the cone B to fit the
coned or taper passage in the said seat, as set forth.
3rd. Seating a fusible plug in a steam boiler from the interior of the furnace or flue
thereof, in the manner set forth.
Dated thioed of Nahan 7000
ROBT. ED. PHILLIPS, M.I.M.E.,
Consulting Engineer and Patent Agent,
Royal Courts Chambers,
70, 71 & 72, Chancery Lane, London, W.C.,
Agent for the Applicant.