Improvements in and relating to Thermal Alarms, Chiefly Designed to be Applied to Bearings for Machinery.
Year: 1888

page_text: Date of Application, 23rd Aug., 1338
Specification Accepted, 19th Oct., 1888
COMPLETE SPECIFICATION.
Improvements in and relating to Thermal Alarms, Chiefly Designed
to be Applied to Bearings for Machinery.
1. CHRISTIAN AGERSKOV, of Copenhagen, in the Kingdom of Denmark, Engineer's
Assistant, 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 relates to a thermal alarmı or apparatus for giving an alarm when a
certain temperature has been exceeded.
The apparatus can be applied to many different purposes, but it is especially
applicable to bearings for shafting of various kinds.
The apparatus comprises a metal tube which is closed at one end and open at the
other end and which is partly filled with an inflammable substance, the upper part
containing a fuze-composition which latter consists of two ingredients normally
separated by a fusible material which will be destroyed by the temperature at which
the apparatus is intended to act, when the two separated compounds of the fuze-
composition mix together and by their mixture become self-ignited.
The open end of the metal tube is closed with a plug which is preferably made of
india rubber or cork but can be made of other suitable substance. Tho fuze-
composition can be composed of any suitable ingredients according to circumstances
but their choice must in any case depend on the material which serves to separate the
two ingredients as they must not be such as to have any destructive effect on the said
material. Where the separating material is formed of paraffin (that being found to be
the most suitable material when the apparatus is applied to journals and bearings)
one of the ingredients of the composition may consist of sulphuric acid and the other
ingredient of a mixture of chlorate of potassium and sugar.
In the accompanying drawing
Figure 1 is a vertical section of a thermal alarm made according to my invention
and drawn to an enlarged scale, and
Figure 2 is a section of an axle bearing showing my apparatus applied
thereto

page_text: a (figure 1) is the tube preferably made of copper, and is the inflammable
substance on the top of which is placed one of the ingredients of the fuze-composition,
consisting in this case of chlorate of potassium mixed with sugar. In the centre of
this mixture is a small hollow sphere or capsule e made of paraffin which is filled
with sulphuric acid s. d is the plug which closes the top of the metal tube a.
The apparatus is placed in a suitable hole or cavity in an axle-bearing for
example, as shown in figure 2, the temperature of which bearing it is required shall
not exceed the degree at which the apparatus is intended to act. If now at any time
the said temperature should be exceeded, the separating material will be destroyed.
In the present case the hollow paraffin capsule or sphere e will be caused to melt
whereby the fuze-composition will first become ignited and then the combustible
material b.
The gases produced by the combustion of the material will force the plug dout
of the metal tube thereby giving the alarm by the sound, light, smoke, and smell
produced. It will be obvious that, if required, the apparatus can further be arranged
to set in action an electric or other alarm apparatus of suitable construction.
The herein before described paraffin capsules or spheres c with their contents can
be made in the following manner: drops of cool sulphuric acid are allowed to fall onto
molten paraffin floating on water cooled from below, the drops of sulphuric acid then
enveloping themselves in the paraffin and by reason of their greater specific gravity
sinking to the bottom, this being a complete proof that each of the paraffin capsules
contains sulphuric acid.
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 :-
1. A thermal alarm in which a fuze-composition is employed which ignites itself
at a certain predetermined temperature, substantially as hereinbefore described.
2. In a thermal alarm, the use of a fuze-composition consisting of two substances
normally separated by a third substance which, under the influence of a predetermined
maximum temperature, will either melt or be destroyed in any other way and so cause
the two substances to come into contact and, through the heat thereby generated,
cause the required ignition, substantially as herein before described.
3. The use of the hereinbefore described fuze-composition together with an
inflammable substance arranged in such a way as to be acted on by the heat
generated by the said fuze-composition and thereby indicating that the temperature
Ias been reached which it is required shall not be exceeded, substantially as herein-
before described.
4. The manufacture of the paraffin capsules or spheres with their contents by causing
drops of cool sulphuric acid to fall onto molten paraffin floating on water cooled from
below, substantially as hereinbefore described.
Natal the 22.1 day of Anout 1888
G. F. REDFERN & Co.,
4, South Street, Finsbury, London,
Agents for the Applicant.