IMPROVEMENT IN FUSIBLE PLUGS
Year: 1885

page_text: I WILLIAM HENRY BAILEY, of the Albion Works, Salford, in the County of
Lancaster, Hydraulic Engineer and Brassfounder, do hereby declare the nature of
said Invention for AN IMPROVEMENT IN FUSIBLE PLUGS to be as follows:-
My invention relates to the plugs of fusible metal which are placed in the skins
of boilers or in the fireboxes so as to melt and allow the steam to escape when a
dangerous heat is reached, my object being to insure the more complete and certain
fusing of the metal of which the plug is composed.
To effect this I cover entirely and completely the fusible metal plug with a disc
or cap of copper, brass, or other hard metal, instead of as at present placing a small
disc of hard metal in the centre of the plug only and leaving the rest of the
fusible metal exposed to the chemical action of the water, causing the formation
of scale.
By the use of this disc or cap the water cannot come in contact with the fusible
metal and as soon as the plug fuses the steam forces the hard metal cap out, thus
opening the plug to its fullest extent and allowing sufficient steam to escape and
extinguish the fire.
H. B. BARLOW,
Agent for Applicant,
4, Mansfield Chambers,
17, St. Ann's Square, Manchester.
I WILLIAM HENRY BAILEY, of the Albion Works, Salford, in the County of
Lancaster, Hydraulic Engineer and Brassfounder, do hereby declare the nature of
said Invention for AN IMPROVEMENT IN FUSIBLE PLUGS, and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement :-
My invention relates to the plugs of fusible metal which are placed in the skins
> of boilers or in the fire boxes so as to melt and allow the steam to escape when a

page_text: dangerous heat is reached, my object being to insure the more complete and certain
fusing of the inetal of which the plug is composed.
To effect this I cover entirely and completely the fusible metal plug with a disc
or cap of copper, brass, or other hard metal instead of, as at present, placing a small
dise of hard metal in the centre of the plug only and leaving the rest of the
fusible metal exposed to the chemical action of the water causing the formation
of scale.
By the use of this disc or cap the water cannot come in contact with the fusible
metal and as soon as the plug fuses the steam forces the hard metal cap out, thus
opening the plug to its fullest extent and allowing sufficient steam to escape and
extinguish the fire.
And in order that my Invention may be fully understood and readily carried
into effect I will describe the accompanying Sheet of Drawings, reference being had
to the figures and letters marked thereon.
Figure 1 is a sectional elevation of my improved fusible plug fixed in position.
Figs. 2 and 3 are detailed views of the plug, and Fig. 4 is a view of Fig. 1 after
the plug has fused showing a clear passage for the escape of steam.
The boiler plate a is tapped to receive the screwed end of a tube b which is open
to the flue or fire box and projects into the water space of the boiler; on the end
of this tube b rests the fusible metal disc c secured centrally to the underside of a
smaller disc or cap d of copper, brass, or other suitable hard metal, see Figs. 2 and 3.
The discs c and d are secured in position on the end of the tube b by the brass or
other metal cap e the centre of which is bored out to exactly fit the copper disc d
and which is tapped to screw on to the outside of the tube b.
As soon as the level of water in the boiler sinks below the top of the cap e and
sufficient heat is generated, the soft metal disc c fuses and the steam forces the
hard metal disc or cap d out, thus opening the plug to its fullest extent and leaving
a free passage, as shown in Fig. 4, for steam to escape from the boiler through the
tube b and extinguish the fire in the flue beneath.
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. A fusible plug in which the upper surface of the soft or fusible metal is
entirely covered and protected from the action of the water in the boiler by a disc,
cap, or piece of copper brass, or other suitable metal for the purpose specified.
2. The combination with the tube b and the cap e of the discs c and d, substan-
tially as and for the purposes herein set forth.