Improvements in Thermostatic Fire-alarms.
Year: 1896

page_text: Date of Application, 20th Oct., 1896--Accepted, 13th Mar., 1897
COMPLETE SPECIFICATION.
Improvements in Thermostatic Fire-alarms.
We, HENRY BAER, Electrician, HERMANN BOSCH, Physician, and WALLING
DION GREANELLE, Commission Merchant, all of No. 24, East 61st Street, in the
City, County and State of New York, U.S.A. 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:-
This invention relates to certain improvements in thermostatic fire-alarms in
which in place of the expansion of a suitable thermostatic-bar under the influence
of the direct heat of the fire the bar is constantly subjected to the influence of
the heat of a suitable flame and the heating effect on the thermostatic-bar
interrupted in case of fire when the smoke caused by the same extinguishes the
heating medium and produces thereby the closing of an electric alarm circuit so
that attention is drawn to the starting fire.
Our invention consists of a thermostatic fire alarm which comprises a thermo-
static-bar that is attached at one end to a non-conducting shelf heated by a gas-
flame or other heat agency and which is connected at its upper free end with a
regulating device by which the supply of gas to the flame is regulated and is also
connected with a detent on which a movable contact is supported contact is released
when the action of the heat agency on the thermostatio-bar is interrupted by the
contraction of said bar so that it forms an electric connection with a stationary
contact and closes an electric circuit by which the alarm of fire is given.
In the accompanying drawings:-
Fig. 1 represents a front elevation of our improved thermostatic fire-alarm
showing the front door of the same in open position so that the interior parts are
in view said parts being shown in normal position.
Fig. 2 is a plan view partly in horizontal section on line 2-2 Fig. 1.
Fig. 3 is a side-elevation of the operative parts of our improved fire-alarm
showing the same in their second position so as to indicate a fire, and
Fig. 4 is a detail horizontal section on line 4-4 Fig. 1.
Similar letters of reference indicate corresponding parts.
Referring to the drawings-A represents the exterior casing of our improved
thermostatic fire alarm which is provided with a hinged door A¹ that is fastened by
a suitable lock a' so that no one except the party in possession of the key has
access to the interior of the fire-alarm."
The casing is provided with bottom and top openings a a which can be opened
or closed by means of small pivoted covers a* so that an up-draught of air from
the lower towards the upper end of the casing can take place. At the inside
bottom walls of the casing and of the cover A' are arranged V-shaped plates a³
that extend over the air openings a a so as to prevent a direct draught of air
through the casing the air being compelled to pass first into the channel formed
by the V-shaped plates a2 and then to the interior of the casing.
At the interior of the casing A is arranged a non-conducting plate or shelf B
which is advantageously made of slate porcelain or other refractory material and
provided with an opening b that is located vertically above a small gas burner C¹
which is arranged at the lower part of the casing A and to which the gas is supplied
by a supply pipe C which enters at the upper part of the casing and extends in
downward direction to the burner C¹. The gas-burner is surrounded by a chimney C*

page_text: which is protected against breakage by suitable rods r that pass through the bottom
of the casing and through the shelf or plate B so as to support the latter in position
in the casing. Below the chimney is arranged a sheet-metal gallery C which is
provided with an opening o and a ring-shaped slide C also provided with an
opening C so that the access of air to the flame can be regulated to keep up the
proper combustion of the gas as shown in Fig. 4. To the shelf B is applied
above the heat-opening b a thermostatic-bar D which is formed in the usual manner
of two thin layers of sheet-metal of different co-efficients of expansion such as brass
and steel which thin layers are riveted together. The lower end of the thermo-
static-bar D is applied to the shelf B while the upper free end is connected at one
side by a pivot-link d with a crank d' of a gas-cock d by which the supply of gas
to the burner C (and thereby the flame) is regulated automatically.
The gas-supply pipe C is further provided above the gas regulating cock d' with
a main gas cock e so that the supply of gas can be shut off entirely when the
thermostat is put up for use or when the same has to be interrupted for some reason
or other.
The gas regulating cock d is necessary so as to provide for the varying pressure
of the gas in the supply pipe and for keeping thereby the heating flame at a
uniform size.
The heated air generated by the flame passes through the opening 6 and acts on
the thermostatic-bar D so as to cause the greater or less expansion of the same
according to the size of the gas flame. The upper end of the thermostatic-bar D
is further connected by a pivot link with an oscillating detent F pivoted at its
lower end to ears f¹ attached to the shelf B and which is provided with a curved
upper end on which rests a weighted and pivoted contact or latch G pivoted to
suitable ears g applied to a post G¹ which is attached to the shelf B and connected
by a conducting wire P with a suitable binding post P' applied to and insulated
from the side wall of the casing. A second shorter post G' provided with a
horizontal fixed contact g is arranged on the shelf B in front of the post G
vertically below the movable contact G and also connected by a conducting wire P
with a second binding post p' which is electrically connected with a suitable fire
alarm circuit arranged in the office of the building or in the office of the watchman
or at some distance from the building in the office of a district messenger company.
The cover A' of the casing is provided with a glass-covered opening a which is
normally closed by means of a pivoted slide-plate a' that can be readily opened
from time to time so as to observe if the heating flame is properly burning at the
interior of the casing.
Our improved thermostatic fire alarm operates as follows:-
When all the parts are in their normal position as shown in Figure 1 and the
thermostatic-bar D is heated by the small gas-flame or.other heating agency below
the same it is sufficiently expanded under the influence of the heat so as not only
to regulate the supply of gas by means of the regulating gas cock d' but also to keep
it expanded or bent to such an extent that the oscillating detent F is moved sideways
so as to support the pivoted contact G in horizontal position on its bent upper end and
prevent the contact from dropping. As soon however as the smoke caused by a fire
enters into the casing and into the lower part of the chimney C the heating gas
flame is extinguished because the smoke shuts out the supply of air to the flame.
Consequently the thermostatic bar commences to cool off and to contract so that
the supply of gas is interrupted by the automatically regulated gas cock d and
simultaneously the oscillating detent F is moved into the position shown in Fig. 3
thus releasing the contact G and producing thereby the dropping of the same by
gravity in contact with the contact piece 9 of the post G whereby the alarm
circuit is closed and the alarm of fire given at the office or other place where the
fire alarm box is located. It appears therefore that our improved thermostatic
fire alarm instead of being based on the direct action of the heat of the fire on a
thermostatic bar and the closing of a circuit by said bar is operated by the
exclusion of air from the fire alarm box and the consequent extinguishment of the

page_text: heating flame and the cooling off of the thermostatic bar whereby the further
supply of gas to the flame is interrupted and the circuit-closing contact automatically
operated. It is obvious therefore that our improved fire alarm is much more
sensitive than the thermostatic fire alarms heretofore in use for the reason that
the smoke usually fills up a room before the fire can exert a sufficient degree
of heat on the thermostatic bar so as to cause the proper action of the same.
Our improved thermostatic fire alarm is comparatively inexpensive, can be
located at any desired point of a building and forms a very effective and
reliable fire alarm for residences, hotels, warehouses, factories, and buildings of
all kinds.
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. In a thermostatic fire-alarm the combination of a thermostatic bar means for
heating said bar a detent connected with the thermostatic bar a movable contact
supported by said detent and another contact adapted to be engaged by said
movable contact whenever the heat action on the thermostatic bar is interrupted
so that an electric circuit is closed and the alarm of fire given substantially as
set forth.
2. In a thermostatic fire alarm the combination with a thermostatic bar of means
for constantly applying a heat.action on said bar a regulating device connected with
the thermostatic bar for regulating the supply of gas to the heating agency a
detent also connected with said thermostatic bar a pivoted contact supported by
said detent and another contact adapted to be engaged by the pivoted contact when
the same is released by the supporting rod so as to close an electric alarm-circuit
substantially as set forth.
3. In a thermostatic fire alarm the combination with a casing provided with
suitable draft-openings of a gas burner at the interior of said casing means for
supplying air to said burner a shelf above the gas burner provided with an opening
vertically above the flame a thermostatic bar applied to the shelf and arranged
above said opening means connected with the free end of the thermostatic bar for
regulating the supply of gas to the flame a detent also connected with the free end
of the thermostatic bar a pivoted contact resting normally on the detent and another
contact which is engaged by the movable contact when the same is released by the
extinction of the flame and the contraction of the thermostatic bar so as to
produce the closing of the electric circuit and the sounding of an alarm substantially
as set forth.
4. A thermostatic fire alarm constructed and arranged to act substantially in the
manner and for the purposes hereinbefore described and as illustrated in the drawings
hereunto annexed.
www
TONGUE & BIRKBECK,
Southampton Buildings, Chancery Lane, London, W.C.,
Agents for the Applicants.