Improvements in Means or Apparatus for use in the Application of Electricity for Heating Liquids, and in Means or Apparatus for Manufacturing the same.
Year: 1893

page_text: Date of Application, 5th Jan., 1893
Comp ete Specification Left, 5th Oct., 1893-Accepted, 5th Jan., 1894
PROVISIONAL SPECIFICATION.
Improvements in Means or Apparatus for use in the Application of
Electricity for Heating Liquids, and in Means or Apparatus for
Manufacturing the same.
We, ROOKES EVELYN BELL CROMPTON, Engineer and HERBERT JOHN
DOWSING, Engineer, both of Mansion House Buildings in the City of London do
hereby declare the nature of this invention to be as follows:-
Where water or other liquids are required to be heated rapidly it is necessary
to bring the water into contact as quickly as possible with an extended heating
surface and further it is desirable to promote the natural circulation of the liquids
so as to pass the whole of the liquid over the heated surface at as rapid a rate
as possible.
In order to effect this we find it convenient to prepare heating tubes which are
placed either within or without the vessels containing the liquid to be heated the
said tubes being connected to the vessel in such a manner that the heating of the
tubes themselves causes a circulation of the liquid within them and the whole of..
the liquid desired to be heated is continuously circulated through the said heating
tubes until the desired temperature is obtained. The process of preparing straight
tubes for this purpose is as follows:
For straight tubes the material of the tube itself may be of copper or any metal
that will stand the desired temperature, and the co-efficient of linear expansion of
which does not differ so widely from that the enamel used as to make the latter
liable to crack when the tube is heated to the working temperature. In preference
we use copper or certain alloys of copper for straight tubes but iron also can be
used. One method of forming heating tubes is to coat the external surface of the
tube with a layer of enamel having a high melting point. The tube while still hot
and the enamel coating in a plastic condition is then mounted in suitable holders on
a lathe so that it can be revolved at any desired speed. The heat may be
maintained by a gas blow pipe with suitable fire clay hood and other protectors so
that the enamel remains plastic while the lathe revolves and the conducting wire is
wound on to it in the form of a spiral; the pitch of this spiral can be correctly
given by a modification of the ordinary lathe screw cutting gear by leading screw
and change wheels. As soon as the required quantity of wire can be wound on it
can be covered with enamel and the process completed in the furnace whilst
rendering the embedding & covering enamels fluent or viscous.
In case however we wish to form these tubes into spiral or other convenient
form so as to get increased length within a given space we in the first instance
form them as straight tubes in the manner above described and afterwards fill them
with a sand of pure silica which has a melting point considerably in excess of that
to which it is necessary to raise the enamel on the tube to bring it to a plastic
condition. After the tubes have been filled with sand and both ends plugged with
fireclay or similar material which will resist the temperature they are raised to a
point at which the enamel becomes plastic and are then carefully bent round a
former into the desired spiral shape. As considerable strain is put upon the
embedded wire at the points on the outside of the bends of the spiral it is important
that the material of this wire should be such as does not lose its ductility and
tenacity at the temperature to which the enamel must be raised in order to soften
it sufficiently. For this reason the various copper wires or those formed of the.
various copper alloys are not suitable, but wires formed of platinum, pure iron,
steel with a small percentage of carbon and several of the steel and nickel alloys can

page_text: be satisfactorily used. On account of the limited size of the surfaces and the
necessity of maintaining the whole of the enamel at an approximately equal
temperature it is necessary to separate the successive lengths of enamelled pipe in
such a manner that there may be no tendency to cracking or distortion of one part
of the enamel owing to its being partially cooled while the adjoining part is being
heated. For this reason it is sometimes convenient to prepare the enamel spiral
and apply it to a series of short rings which can be afterwards slipped on to the
tube and attached to it in any convenient manner.
We sometimes form an electrical geyser or apparatus required for rapidly
heating water for baths or other purposes by fixing within the cylindrical vessel
containing the water a spiral tube formed in the manner above described the spiral
being open at both ends, the conducting wire being carried insulated through the
sides of the outer vessel to terminals properly placed; the vessel being filled with
water the required current is then passed through the wire which heats the whole
tube, circulation is at once set up through the tube and the whole of the water in
the vessel passes and re-passes through the spiral until it is heated to the desired
temperature. The above description is typical of the mode of employment of
either the straight or spiral tubes that are herein described.
In another form of apparatus for rapidly heating liquids we fix within the vessel
containing the liquid to be heated a certain number of plain tubes either in a
vertical or inclined position and within and concentric with each of them we fix a
wire spirally which is insulated from the liquid to be heated with a uniform coat of
insulating enamel of a sufficiently resistant nature to stand the desired temperature
without cracking. In this case as in the other cases above described care must be
taken to use one of the enamels to be emlpoyed in a fluent or viscous condition in
the furnace, and which enamel has a co-efficient of linear expansion sufficiently
near to that of the wire from which the spiral is formed.
Dated this 5th day of January 1892
WM. BROOKES & SON,
55 & 56, Chancery Lane, London, Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Means or Apparatus for use in the Application of
Electricity for Heating Liquids, and in Means or Apparatus for
Manufacturing the same.
We ROOKES EVELYN BELL CROMPTON Engineer, and HERBERT JOHN
DOWSING, Engineer, both of Mansion House Buildings in the City of London,
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:-
Where water, air or other fluids are required to be heated rapidly it is necessary
to bring the water into contact as quickly as possible with an extended heating
surface and further it is desirable to promote the natural circulation of the water,
air or other fluids so as to pass the whole of the water, air or other fluid over the
heated surface at as rapid a rate as possible. In order to effect this we find it cou-
venient to prepare heating tubes which are placed either within or without the
vessels containing the water air or other fluid to be heated the said tubes being
connected to the vessel in such a manner that the heating of the tubes themselves
causes a circulation of the fluid within them and the whole of the water air or
other fluid desired to be heated is continuously circulated through the said heating
tubes until the desired temperature is obtained. The process of preparing straight
tubes for this purpose is as follows:-
For straight tubes the material of the tube itself may be of copper or any metal

page_text: that will stand the desired temperature, and the co-efficient of linear expansion of
which does not differ so widely from that of the enamel used as to make the latter liable
to crack when the tube is heated to the working temperature. In preference we
use copper or certain alloys of copper for straight tubes but iron also can be used. One
method of forming heating tubes is to coat the external surface of the inner tube
with a layer of enamel having a high melting point. The tube while still hot and
the enamel coating in a plastic condition is then mounted in suitable holders on a
lathe or winder so that it can be revolved at any desired speed.
The heat may be maintained by a gas blow pipe or furnace with suitable fire
clay hood or muffle and other protectors so that the enamel remains plastic while
the lathe revolves and the conducting wire is wound on to it in the form of a spiral
but preferably with wire worked to and fro to secure increased elasticity under
expansion and contraction and also to afford greater surface of wire in the same
length of spiral, the pitch of this spiral can be correctly given by the utilization of
the ordinary lathe screw cutting gear by leading screw and change wheels.
As soon as the required quantity of wire can be wound on it can be covered with
enamel and the process completed in the, furnace whilst rendering the embedding
and covering enamels fluent and viscous (as in the case of the plates described in
the Specification of our Letters Patent No. 17091, dated September 24th 1892).
In case however we wish to form these tubes into spiral or other convenient form so
as to get increased length within a given space we in the first instance form them.
as straight tubes in the manner above described and afterwards fill them with a sand
of pure silica which has a melting point considerably in excess of that to which it
is necessary to raise the enamel on the tube to bring it to a plastic condition.
After the tubes have been filled with sand and both ends plugged with fireclay or
similar material which will resist the temperature they are raised to a point at
which the enamel becomes plastic and are then carefully bent round a former die.or
strapping device into the desired spiral shape.
As considerable strain is put upon the embedded wire at the points on the outside
of the bends of the spiral it is important that the material of this wire should be
such as does not loose its ductility and tenacity at the temperature to which the
enamel must be raised in order to soften it sufficiently. For this reason the various
copper wires or those formed of the various copper alloys are not suitable, but
wires formed of platinum, suitably pure iron, steel with a small per centage of
carbon and several of the steel and nickel alloys can be satisfactorily used.
account of the limited size of the surfaces and the necessity of maintaining the
whole of the enamel at an approximately equal temperature it is necessary to
separate the successive lengths of enamelled pipe in such a manner that there may
be no tendency to cracking or distortion of one part of the enamel owing to its
being partially cooled while the adjoining part is being heated.
On
For this reason it is sometimes convenient to prepare the enamel spiral and apply
it to a series of short rings which can be afterwards slipped on to the tube and
attached to it in any convenient manner.
:
We sometimes form an electrical geyser or apparatus required for rapidly
heating water for baths or other purposes by fixing within the cylindrical vessel or
covering a spiral tube formed in the manner above described the spiral being open
at both ends, the conducting wire being carried insulated through the sides of the
outer vessel to terminals properly placed; the required current is then passed
through the wire which heats the whole tube, water is allowed to pass through the
tube or spiral when it will become heated to the desired temperature. The above
description is typical of the mode of employment of either the straight or spiral
tubes that are herein described.

page_text: coating thereof and a³ is the insulating coating for the spirally arranged resistance b.
These rings or sections of tube a and their supported coatings of enamel and their
sections of the electrical resistances are joined up on the pipe so that electrical
continuity of the wires is secured. The left hand portion of Fig. 1 is shewn in
section and the right hand half external of the ring.
Fig. 2 shows a sectional diagram of a geyser or a rapid water heater, a being a
cylindrical heater arranged with layers of enamel having helical winding embodied
therein as already described. is an outer protecting case and ¹ the water
container which circulates up within and down without the hollow case h.
Fig. 3 shews a modification in which the water passage is arranged through a
cylindrical coil a heated by resistances helically wound thereon, being a protective
case..
In another form of apparatus we fix within the vessel containing the fluid to be
heated a certain number of plain tubes either in a vertical or inclined position and
within and concentric with each of them we fix a wire spirally which is insulated
from the fluid to be heated with a uniform coat of insulating enamel of a sufficiently
resistant nature suitably protected by a cover in most cases to stand the desired
temperature without cracking. In this case as in other cases above described care
must be taken to use one of the enamels to be employed in a fluent or viscous
condition in the furnace (as described in the former Specification already mentioned)
and which enamel has a coefficient of linear expansion sufficiently r
the wire from which the spiral is formed...
near to that of
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is:
1. The combination or arrangement and use of parts of means or apparatus for
utilizing the heating powers of electrical energy in its passage through resistances
embedded in enamelled: plates or bodies all substantially as and for the purposes
set forth.
2. The method of and means, or apparatus for promoting the rapid heating of
fluids as water, air and the like by means of tubes of metal placed within, or
without, or within and without the fluid containing vessel, said tubes having applied
to them electrical conductors wound spirally thereon and supported, attached and
secured insulated thereto by enamel of suitable character, all substantially as and
for the purpose set forth.
3. The manufacture and use of tubes for electrical heating, or analogous
apparatus having electrical conductors wound spirally thereon and retained thereun
embedded in and covered by enamel, all substantially in manner and for the
purposes set forth.
+
4. The method of manufacturing spiral and other forms of heating tubes
arranged so as to attain increased superficial area, and covering the same with
enamel and conducting wire so that the enamel forms the means of support, attach-
ment and covering between the heated tubes and the heating electrical conductors,
and the use of such heating tubes in apparatus for cooking, heating and analogous
purposes by the aid of electricity substantially as set forth.
5. The construction and arrangement of heating plates, having electrical
conductors of wire or strip embodied therewith by means of enamel such as
described when said enamel was in a softened condition, within vessels containing
the water, air or other fluid to be heated but from which the conductors are
insulated substantially as set forth.
Dand the
1000
WM. BROOKES & SON,
55 & 56, Chancery Lane, London, Agents for the Applicants.