An Improved Fire Indicator.
Year: 1897

page_text: Date of Application, 13th Sept., 1897
Complete Specification Left, 4th June, 1898-Accepted, 16th July, 1898
An Improved Fire Indicator.
I, GEORGE CROYDON MARKS, of 18, Southampton Buildings, Chancery Lane,
London, W.C., Consulting Engineer (a communication from La Societe G.
Drouot et Cie., 42, Boulevard Bonne-Nouvelle, Paris, in the French Republic),
do hereby declare the nature of this invention to be as follows:-
My invention relates to an improved fire indicator, and has for its object to
certainly indicate the existence of a fire in the vicinity in which it may be placed.
My invention consists of a chamber having a diaphragm which is capable of
expansion by reason of the expansion of air contained in the chamber so as to
cause contact to be made for the completion of an electric circuit, so that thereby
an alarm may be rung.
In carrying my invention into effect I provide a cylindrical chamber of copper,
upon the upper face of which a thin corrugated diaphragm is provided, whose
outer peripheral edges lie in the rebate of a flange of the chamber which is her-
metically closed. Upon the central part of this chamber a silver point is pro-
vided for contact with an adjusting contact screw. This chamber is carried by
brackets which are fixed to the structure or place to which the indicator is to be
applied. Above the diaphragm of the chamber and in alignment therewith is
provided an adjusting contact screw, whose extremity has preferably a silver
point, through which the electric circuit passes. This adjusting screw is mounted
within a conducting collar at whose upper part a bridge piece or covering is secured
which carries a contact screw by which the wire terminal connection is held, and
covers the head of the adjusting screw so as to preclude accidental movement.
The conducting collar is mounted upon a non-conducting flange piece which is
in turn mounted upon a carrying plate or bracket that is held and secured upon
the peripheral flange of the chamber. A screw contact is provided upon the
carrying plate or bracket to which the other terminal of the circuit is secured.
It will be understood that the current passes through such carrying plate to
the chamber or direct to the diaphragm, and when the temperature has reached
the predetermined limit, through the adjusting contact screw, and so the circuit
is completed and the alarm is rung.
It will be understood that in the use of a thin corrugated diaphragm the
expansion of air causes the central portion to move outwardly, while its peripheral
edges would be retained.
The indicator may be provided with a cover so as to preclude its disarrangement
by accidental causes, and it may be so modified in construction as to be placed
in any part of the building in which it is required without departing from the
essential features of my invention.
The indicator may also be used wherever it is required to indicate a certain

page_text: predetermined temperature in places which are subject to temperature
variation.
Dated this 13th day of September 1897.
An Improved Fire Indicator.
I, GEORGE CROYDON MARKS, of 18, Southampton Buildings, Chancery Lane,
London, W.C., Consulting Engineer, (a communication from La Societe G.
Drouot et Cie., of 42, Boulevard Bonne-Nouvelle, Paris, in the French Republic),
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 an improved fire indicator, and has for its object to
certainly indicate the existence of a fire in the vicinity in which it is placed.
My invention consists of a chamber having a diaphragm which is capable of
outward expansion by reason of its linear expansion and by reason of its expansion
of air contained in the chamber so as to cause contact to be made for the com-
pletion of an electric circuit, so that thereby an alarm may be rung.
My invention is illustrated in the accompanying drawings in which Figure 1,
represents in sectional elevation a fire indicator made in accordance with the
invention, while Figure 2, is a plan corresponding thereto.
In carrying my invention into effect as illustrated in the accompanying draw-
ings I provide a cylindrical chamber C, D, preferably of copper upon the upper
face of which a thin corrugated diaphragm o is mounted, whose outer peripheral
edge lies in the rebate of a flange m n of the chamber which is hermetically
closed. Upon the central part of this chamber a silver point may be provided
for contact with an adjusting screw V. The chamber C D is carried by
brackets HH which are fixed to the structure or place to which the indicator is
to be applied. Above the diaphragm o of the chamber C D and in alignment
therewith is provided the adjusting contact screw V, whose extremity is prefer-
ably a silver point to contact with the silver point provided centrally upon the
diaphragm o so that electric current may pass therethrough. This adjusting
screw is mounted within a conducting collar a at whose upper part a bridge
piece or covering R is secured, being preferably screwed thereto, such bridge
piece or covering carrying a contact screw by which the wire terminal connec-
tion is held, the bridge piece covering the head of the adjusting screw V so aš
to prevent accidental movement.
The conducting collar a is mounted upon a non-conducting flange piece b
which is in turn mounted upon the carrying plate or bracket A, B, that is held
and secured. upon the peripheral flange m n of the chamber C, D, and secured
thereto by means of screwed studs A A contact screw K is provided upon the
carrying plate or bracket A B to which the wire terminal of the circuit is
secured.
It will be understood that the current passes through the carrying plate, through
the chamber or diaphragm or direct to the diaphragm and when the predetermined
temperature has been obtained contact is made by the diaphragm o with
the adjusting screw V whereby the current passes through so that thereby the
circuit is completed and the alarm is rung.

page_text: It will be understood that in the use of a thin corrugated diaphragm its linear
expansion and the expansion of air within the chamber causes the central portion
to move outwardly while its peripheral edges are retained.
The indicator may be provided with a cover so as to preclude the arrangement
from accidental causes and it can be so modified in construction as to be placed
in any part of the building in which it is required. The indicator may also be
used wherever it is required to indicate a certain predetermined temperature in
places which are subject to temperature variation.
•
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.) An improved fire indicator consisting of a chamber hermetically closed,
having upon its face a corrugated diaphragm capable of outward expansion on
increase of temperature by reason of its own linear expansion, and by reason of
the expansion of the air within the chamber, for effecting the closing of an
electric circuit, and for the purpose substantially as described and illustrated.
2.) An improved fire indicator substantially as described and indicated.
ALL
£ 1000
MARKS & CLERK,
18, Southampton Buildings, London, W.C., and
13, Temple Street, Birmingham, Agents.