Improvements in Boilers, in part especially applicable to Domestic Hot Water Supply Boilers.
Year: 1891

page_text: Date of Application, 14th Apr., 1891
Complete Specification Left 14th Jan., 1392-Accepted, 9th Apr., 1892
PROVISIONAL SPECIFICATION.
Improvements in Boilers, in part especially applicable to Domestic
Hot Water Supply Boilers.
I. ROBERT DAVIES of 424 Borough Road Birkenhead in the County of Chester,
Builder and Contractor, do hereby declare the nature of this invention to be as
follow-
―: -
My present invention relates to boilers, and is in part especially applicable to
domestic hot water supply boilers.
It is found in such boilers that when the water
supply is cut off by frost or other causes the water in the boiler soon vaporises,
and as a result the metal of the boiler is raised to a very high temperature; on
the resumption of the water supply the water on entering the boiler and coming
into contact with the heated metal, immediately flashes off into steam and a very
considerable pressure is at once produced, which, taken in conjunction with the
unequal contraction of the metal, is sufficient in most cases to burst the boiler even
when there is an opening for the steam to escape, and the object of my invention is
to prevent such explosions.
My invention also relates to an improved mode of fixing the capping in high
pressure hot water supply boilers.
According to my present invention I construct such boilers as follows;-
I lead the water supply pipe through the top of the boiler, through the interior
and out through the bottom of the boiler so that if the end of the pipe be not
plugged up, the water passes directly into the fire. I plug the said end up with
a fusible plug which is composed of a metal or alloy which fuses at a temperature
just exceeding the maximum temperature to which it is thought desirable to raise
the metal of the boiler. From the lower portion of this supply pipe within the
boiler I lead a branch pipe up to the top of the boiler then down to the lower portion
where I form the outlet of the pipe.
It will be seen that so long as the fusible plug closes the end of the supply pipe
leading to the fire, the water will be forced into the boiler through the branch
pipe, but that should the supply be cut off from any cause and the said plug fuse,
on the resumption of the water supply the water will pass straight through into
the fire instead of coming into contact with the heated boiler and thereby causing
an explosion.
I prefer generally to provide a second fusible plug in the end of the boiler so that
when the boiler is heated abnormally, both plugs fuse and a free circulation of air
through the openings thus formed is insured.
The fusible plugs are screwed externally and the holes into which they fit
are tapped-in the case of the supply pipe the end of the pipe fits into a ferrule
screwed into the boiler shell, and this ferrule is tapped, so that the plugs have
simply to be screwed into place.
Referring now to my improvement in the capping, I make the opening
in the top of the boiler oval and I fit thereto two caps, an inner and an
outer cap.
The inner cap has a projecting ridge on its upper surface which determines its
proper position in the oval hole; the under portion of periphery of the outer
cap is indented to fit loosely over this projecting ridge, the adjacent portion of the
said periphery fitting loosely into the oval hole.
The outer dimensions of the caps or covers are greater than those of the hole and
the joint is made between the overlapping surfaces.
A screw or bolt is cast or otherwise secured to the lower cap and passes through

page_text: the upper cap, the pressure necessary to make the joint being obtained by tightening
a nut which bears on the upper cap.
It will be seen that by this construction it is impossible to make the joint with the
lower cap out of position-a mistake frequently made by careless workmen with
the usual construction.
The arrangement described whereby when the boiler becomes unduly heated,
the feed water is led into the fire, is also applicable to most if not all forms of
boilers.
Dated this 7th day of Anril 1891
SLOAN & LLOYD BARNES,
Castle Chambers, 26, Castle Street, Liverpool, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Boilers, in part especially applicable to Domestic
Hot Water Supply Boilers.
I, ROBERT DAVIES, formerly of 424 Borough Road, but now of 23 Whetstone
Lane, Birkenhead in the County of Chester, Builder and Contractor, 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 present invention relates to boilers and is in part especially applicable to
domestic hot water supply boilers. It is found in such boilers that when the water
supply is cut off by frost or other causes, the water in the boiler soon vaporises,
and as a result the metal of the boiler is raised to a very high temperature; on
the resumption of the water supply, the water on entering the boiler and coming
into contact with the heated metal, immediately flashes off into steam and a very
considerable pressure is at once produced, which, taken in conjunction with the
unequal contraction of the metal, is sufficient in most cases to burst the boiler even
when there is an opening for the steam to escape, and the object of my invention is
to prevent such explosions.
My invention also relates to an improved mode of fixing the capping in high
pressure hot water supply boilers.
According to my present invention I construct such boilers as follows:-
I lead the water supply or feed pipe through the top of the boiler, through the
interior and out through the bottom of the boiler into the flue or fire place thereof,
so that if the end of the pipe be not plugged up, the water passes directly into the
fire. I plug the said end up with a fusible plug which is composed of a metal or
alloy which fuses at a temperature just exceeding the maximum temperature
to which it is thought desirable to raise the metal of the boiler. From the
lower portion of this supply pipe, within the boiler, I lead a branch pipe up to
the top of the boiler then down to the lower portion where I form the outlet of
the pipe.
It will be seen that so long as the fusible plug closes the end of the supply
pipe leading to the fire, the water will be forced into the boiler through the branch
pipe, but that should the supply be cut off from any cause and the said plug fuse,
on the resumption of the water supply, the water will pass straight through into the
fire instead of coming into contact with the heated boiler and thereby causing an
explosion.
The accompanying drawings show the application of my invention to a domestic
hot water supply boiler;
Fig. 1 is a vertical section on the line AA of Figs. I and III, the internal
pipes being shown, in part, in front of the line of section; Fig. 1 is a section on the
line B B of Fig. III and Fig. III is a plan.

page_text: Throughout the drawings similar parts are indicated by the same reference
figure, and in the case of section, the direction in which they are viewed is
indicated by the small arrows placed adjacent to the letters denoting the plane of
section.
1 is the boiler formed with the flues 2, which is built into the back of the fire
place in the usual way; 3 is wat supply pipe which enters the boiler by
means of t. srewed union 4. The supply pipe 3 is carried through the boiler to
the screwed ferrule 5 placed on the crown of one of the flues and a branch 3' is
carried to a similar ferrule placed also at the crown of one of the flues and
as close as possible to the front of the boiler where the heat is most intense.
The ferrules and are screwed internally and externally; they are screwed
into place from without and at the same time screwed over the ends of the
pipes 3, 31.
6, 6 are the fusible plugs which are threaded, and screwed from without
into the ferrules; the portions of the ferrules fitting against the boiler shell and
the fusible plugs are preferably made with a slight taper so as to facilitate a fluid-
tight connection. The plugs are made of any of the well known compositions, used
for the purpose, which melt at the desired temperature.
3 is a branch from the supply pipe by which the water supply enters the boiler
So long as the ends of the pipes 3, 3' remain plugged it is made of syphon form
as shown and the bend carried well up within the boiler in order to minimise as
far as possible the possibility of water passing through it when the plugs are
melted, for the same reason it is preferably taken from the branch 3' rather than
the direct pipe 3 and the branch 31 is carried away from 3 abruptly at a right
angle. The pipe 3 is bent as shown within the boiler simply to keep the union +
well back clear of the brickwork setting.
7 is the delivery pipe by which the hot water leaves the boiler.
It will be seen that in the event of the boiler becoming unduly heated and
the fusible plugs melting, not only is the water prevented from entering the
boiler, and the fire probably extinguished, on the resumption of the water
supply, but the hot water re-ervoir or cylinder is put in free communication
with the atmosphere and therefore relieved of all pressure either from without
or within.
The branch 3 and second fusible plug 6 are not essential features of my
invention, they might be dispensed with and the branch 3 taken directly
from the pipe 3; the arrangement shown is however preferable for the reason
already stated and for the further reason that either of the plugs might fail
Lo inelt.
The arrangement of supply pipes and fusible plugs illustrated in connection with
domestic hot water supply boilers is obviously applicable with slight modification
to most if not all forms of steam boilers.
Referring now to my improvements in the capping or means of closing the boiler,
I make the opening 8 in the top of the boiler oval and I fit thereto two caps,-an
inner and an outer cap, 9 and 10 respectively.
The inner cap has a projecting ridge 11 on its upper surface which determines
its proper position in the oval hole; the under portion of the periphery of
the outer cap is indented at 12 to fit loosely over this projecting ridge, the
adjacent portion of the said periphery at 13 fitting loosely into the oval hole.
The outer dimensions of the caps or covers are greater than those of the hole and
the joint is made between the overlapping surfaces.
A screw or bolt 14 is east or otherwise secured to the inner cap and passes through
the outer cap, the pressure necessary to make the joint being obtained by tightening
a nut 15 which bears on the outer cap.
It will be seen that by this construction it is impossible to make the joint with
the inner cap out of position-a mistake frequently made by careless workmen with
the usual construction.

page_text: Having now particularly described and a-certained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what!
claim is ;-
1. The improvement in boilers which consists in leading the water supply
pipe through the boiler and plugging the outer end or ends thereof with one
or more fusible plugs, and providing within the boiler a branch from the said supply
pipe through which the boiler receives its supply, substantially as de-cribed and
illustrated.
2. In domestic hot water supply apparatus, the combination of the water supply
pipe 3, 31, fusible plugs 6, 61 "and supply branch 31 substantially as and for the
purpose described and illustrated.
3. The improved capping or means for closing domestic hot water supply boilers,
substantially as described and illustrated.
Dated this 13th day of January 189)
SLOAN & LLOYD BARNES,
Castle Chambers, 26, Castle Street, Liverpool, Agents for the Applicant.