US2027068A

US2027068A - Fire alarm system

Info

Publication number: US2027068A
Application number: US631666A
Authority: US
Inventors: Jr William M Siddall
Original assignee: Individual
Current assignee: Individual
Priority date: 1932-09-03
Filing date: 1932-09-03
Publication date: 1936-01-07
Anticipated expiration: 1953-01-07

Description

Jan. 7, I936. w. M. SlDDALL, JR

FIRE ALARM SYSTEM Filed Sept. 3,1932

INVENTOR.

I ATTORNEY 7' 'Pii nted Uan. 1, me

UNITED STATES PATENT OFFICE.

FIRE ALARM SYSTEM wmiam M. Siddall, .m, East Orange, N. J. Application September a, 1932, Serial No. 631,666 18 Claims. (01. 117-355) vide a novel and improved combination of a fluid.

pressure fire alarm system and an electrical fire alarm system of the general character described wherein the two systems may initiate signals independently of each other so that the advantages of both systems shall be obtained in the) same installation'an'd protection against fire shall be greatly increased by the two superposed or combined systems; and to provide such a combina- 20 tion system wherein the tubing of the fluid pressure system shall serve also as an electrical conductor, instead .01 wiring, for the electrical sysv tem, so upon a break in the tubing a signalshall .be operated, whereby both the tubing and the I as electrical circuit s'li'ali be under constant test or .constantly supervised and trouble in the system can bequickly discovered and remedied.

Another object is to provide such a combined fiuid pressurekand electrical fire alarmsystem so embodying novel and improved features of con; -struction wherein the fluid pressure system may be utilized to operate s; local signal in case 01' fire, for example a fire of short duration or low temperature, and the electrical system may operate 35 a distant or central signal after a fire has con- .-tinued for a certain time or has caused a predetermined higher temperature.

'1 Further objects are to provide a combined fluid pressure and electrical fire alarm system embody- 40 ing novel and improved features or construction including a loop of tubing, wherein both the sig nal-initiat'ing iiuidpressure actuated device 'and th thermo-responsive device control operation responsive signal-initiating device of the electrical system to the tubing of the fluid pressure system; to provide a combined fluid pressure and electrical fire'alarm system wherein the tubing shall be formed of sections having their ends in v spaced relation which shall be connected by 5 sleeves or nipples of insulation, and the thermoresponsive signal-actuating devices shall be electrically connected across or bridge said spaced and insulated ends of the tubing sections so that said tubing sections and said thermo-responsive devices can be electrically connected in series; to provide a fluid pressure fire alarm system which shall be under constant test or electrical supervision by connection of the tubing in an electrical signalling circuit and enclosing the tubing in elecl 5 trical insulation, so that a break in said tubing will interrupt the electric circuit and cause operation of the signal; to provide novel and improved means associated with the thermoresponsive circuit changing mechanism operable upon operation of said mechanism for identifying the location where such mechanism has been operated; and to obtain other advantages and results as willbe brought out by the following description; v Referring to the accompanying drawing in which corresponding and like parts are designated throughout the several views .by the same reference characters, 1

Figure-1 is a diagrammatic illustration of .a

combined 'fluid pressure and electrical fire alarm system embodying myinvention.

Figure 2 is a similarview or another form of the invention.

Figure 3 is an enlarged verticalsectional view through one of the air chambers forming a part of the fluid conduit. I

Figure :1 is a similar view of one of the insulating nipples forminga part 01 the fluid conduit.

Figure 5 is a composite sectional elevation 40 showing the insulating connection to the tubing 01 one. or the fluid pressure actuated signal-initiating devices.

Figure 6 is a diagrammatic illustration of a modification or the invention,

Figure 7 is an enlarged transverse sectional view' on the line 'I'l of Figure 6, and s Figure 8 is a view similar to Figure 4, showing another modification of the invention.

Specifically describing the embodiment of the invention illustrated in Figures 1, 3 and 4, my fire alarm system includes a conduit containing a fluid which is a non-conductor oi. electricity extending through'the area to be protectedagainst fire, which is shown as composed er a plurality of sections I of electricity conducting tubing 2 which is enclosed in a casing of electrical insulating material 3. The adjacent ends of certain of the sections I are connected together in electrically insulated relation as by sleeves or nipples 4 of electrical insulating material which tele-.

scopically receive the ends of the sections of the tubing and hold them in spaced relation to form a continuous conduit for fluid.

At each end of the fluid conduit is connected a fluid actuated signal-initiating device 5, for example a diaphragm of known construction, at least one wall of which will be moved or distended by fluid pressure generated in the fluid conduit by the heating of any part of the length thereof. These signal-initiating devices cooperate with a signal actuating mechanism for producing a signal upon increase in pressure in the fluid conduit. As shown, the devices 5 are electrically connected by a wire 5A and each of them has an electric switch contact Ii which cooperates with another contact I to control a circuit including the signal-initiating device, a source of electricity 8 and a signal, for example a bell 9. The switch contacts 6 and 1 are normally in spaced relation but upon an increase in pressure in the tubing of a predetermined amount, the contacts 6 and 1 are moved into engagement by the devices 5 so as to cause an actuation of the signals 9. Obviously, only one signal initiating device is necessary, and any other suitable signal actuating mechanism might be utilized.

The signal-initiating devices 5 are connected to the fluid conduit in electrically insulated relation, as by a sleeve II) of electrical insulating material (see especially Fig. 5), and a suitable vent or breathing opening is provided for each signalinitiating device to permit the fluid pressure in the conduit to become reduced to atmospheric pressure after such pressure in the conduit has been increased by heat. As shown, this vent consists of a restricted passage II in the sleeve III which communicates with the signal-initiating device.

If desired, the capacity of the fluid conduit may be increased to provide quicker response of the signal initiating devices to heat, by the use of air chambers I2. These air chambers are connected between the sections I of the conduit in insulated relation thereto, and as shown each air chamber comprises a body I3 formed of insulating material through the walls of which the ends of the tubing sections extend in spaced relation to each other as clearly shown in Figure 3 of the drawing. The air chamber preferably has a removable cover I4, and the capacity of the air chamber may be varied by interchanging covers having difierent degrees of concavity.

In accordance with the invention, the tubing 2 of the fluid conduit also serves as an electrical conductor instead of wiring, for an electrical flre alarm system, and the adjacent ends of the tubing sections are electrically connected by thermoresponsive circuit changing mechanism I5 of suitable known constructionj such, for example, as bi-metallic thermo-responsive or fusible metal strips, that illustratively indicated being mounted on the insulating sleeves or nipples 4 and/or the air chambers I2, by means of suitable supports I6 which are in electrical contact with the tubing sections, but such mechanism may be part of a standard sprinkler head of a sprinkler systeam. With this arrangement, the thermo-responsive circuit changing mechanisms I5 bridge the conduit are electrically connected in circuit with a signal actuating mechanism of any suitable known construction; preferably a relay or .trip including an electromagnetic coil H which has one terminal electrically connected to the tubing at one end of the'conduit and its other terminal connected to the tubing at the other end of the conduit by the respective wires I8 and I9. The coil II cooperates with'an armature detent 20 which controls a spring actuated signal operating mechanism or signal transmitter 23 of known construction. This mechanism 23 includes a spring actuated shaft 24 on which. is mounted a detent disc 25 having a notch 26 to be engaged by the armature detent lever 20. The mechanism 23 also includes a disc 21 having a plurality of projections 28 thereon switch contact 29 to oscillate the same into and out of engagement with another switch contact 30. The

switch contacts

29 and 30 are connected in shunt with the coil H by the wires 3| and 32 and in circuit with a suitable signal or signalreceiving apparatus 34 and a source of electricity 35. The signal-operating mechanism 23 is normally held against operation by the armature detent lever 20 which is held in the notch 26 by a tension spring 36.

In operation, current normally flows from the source 35 through the wire I9, the tubing sections 2, and the thermo-responsive circuit changing mechanism sistance so that the current is shunted around the coil. Upon a variation in the circuit by operation or by opening of the thermo-responsive circuit changing mechanism I5 or a break in the tubing, the current electromagnetic coil I! which is thereby energized and actuates the armature detent lever 24 out of the notch 26. Thereupon'the signal-operating mechanism 23 is actuated to successively make and break the circuit through the contacts I5, the coil I! being of high reis caused toflow through the 29 and 30 and operate the signal or signal-receiving apparatus 34 in the usual manner. This signal or signal-receiving apparatus 34 may be what is sometimes termed the' signal receiver of the apparatus commonly used in central stations. The projections 28 provide a certain signal and correspond to a certain local station, for example, a particular building or room, and each local I station has a different number and arrangement of projections 28 in its corresponding signal-opcrating mechanism.

From the foregoing it will be observed that the signal-initiating devices 5 will be operated by fluid pressure generated in the tubing by a fire which heats any part of the length of the tubing and may serve as -a local as would be incident to a small flre of short duration. The thermo-responsive circuit changing sig al to operate at a low predetermined temperature, for example mechanism I5 may be operated at higher predetermined temperatures, for example, when a fire is large or of long duration, and cause actuation of the signal or signal-receiving apparatus 34 which may be remote from the source of fire, for example, at a central station. Both thev fluid pressure conduit and the electrical circuit through the tubing are under constant supervision since a break in the tubing will cause operation of the signal or signal-receiving apparatus 34.

v Figure 2 shows a construction in general simi-' lar to that shown in Figure 1, the main difference being that the fluid actuated signal-initiating devices 31 are electrically connected to the tubing sections and carry switch contacts 38' which cooperate with other contacts 39 connected in circuit with the signal actuating mechanism.

The contacts 38 correspond to the ends of the tubing in the form of the invention shown in Figure 1. One contact 39 is connected to one of the terminals of the relaycoil H, while the other contact 39 is connected to the opposite terminal of the relay coil, through the respective wires i8 and iii. The

contacts

29, 30, the signal or signal-receiving device 34, and the source of electricity, are connected in shunt relation with the coil l'l exactly as shown in Figure 1.

In operation, the signal actuating apparatus is controlled by both the fluid pressure signal-initiating device and the thermo-responsive circuit changing mechanism l5. The

contacts

38, 39 are normally closed and a major portion of the electric current passes around the relay coil l1. Upon an increase in pressure in the fluid conduit, one or both of the

contacts

38, 39 is opened which causes the current to pass through the coil l1 and set into operation the signal operating mechanism as described in connection with- Figure 1. Upon an operation of thermo-responsive circuit changing mechanism I or upon a break in the tubing, the

contacts

38, 39 remain closed, but the current passes through the relay coil l1, so as to cause operation of the signal operating mechanism. The tubing and the electric circuit therethrough including

switch contacts

38, 39 are under constant electrical supervision.

In Figures 6 and '7 of the drawing, I have shown an electrically supervised fluid pressure fire alarm system which includes a fluid conduit 40 formed of electricity conducting tubing 4| enclosed or sheathed in electrical insulating material 42. The signal-initiating devices 43 and the signal actuating mechanism 44 are shown as identical with the devices 5 and the signal actuating mechanism 68 of the form of the inventionshown in Figure l.

A relay coil 45 is electrically connected in series with the tubing 4| and a source of electricity 46 by wires 41 and 48. The relay coil controls a switch 49 which is in circuit with a signal 50 and the source 46. The current from the source 45 normally passes through the tubing, and the relay coil 45 so as to energize the latter, which holds the switch normally open. Should a break in the tubing or wiring occur, the circuit through the relay will be interrupted, whereupon the switch .49 will be closed so as to operate the signal 50 and indicate that the tubing or wiring has been broken.

As will readily appear to those skilled in the art, any known mechanism for detecting grounding of an electric circuit, may be utilized to indicate it and when the tubing of the fluid conduit is grounded.

In Figure 8 of the drawing, I have shown anchannel for fluid and a normally closed path for other modification of the invention wherein a resistor 5| is connected in parallel circuit with each unit of the thermo-responsive circuit changing mechanism l5. This resistor may be a simple resistance coil, signal bell, incandescent 6 lamp or the like. Preferably the resistor has such a resistance value that the major portion of the currentwill pass normally through theswitch, and the resistor is so related to the thermo-responsive circuit changing mechanism and the trip 10 coil I! that when the switch is operated or opened by a rise in temperature, as by a fire, the current is caused to pass through the resistor whereby resistance in the circuit is changed so that the trip coil I1 is energized to cause operation of the signal actuating mechanism 23. Where the re-- sistor 5! is in the form of a signal, such as an incandescent lamp, the signal or lamp will be operated so as to indicate that the thermo-responsive circuit changing mechanism has been operated, whereby the location of the thermo-responsive circuit changing mechanism which has been'operated, as well as the location of the fire which has caused operation of the system, can be easily and quickly ascertained.

Obviously the details of construction of the fire alarm system may be widelymodified and changed without departing from the spirit or scope of the invention. Also, many different types of fluid pressure signal-initiating devices, thermo sulated sections interconnected through fixed temperature fire detecting circuit changing mechanism, said fixed temperature circuit changing mechanism being located at said tubing in. position for subjection to the same abnormal temperature condition as said tubing, signal manifesting mechanism comprising a signal transmitter involving means for initiating the activity thereof responsive to impairment of the ,current path which includes said loop, a signal receiver responsive to activity of said transmitter, a second circuit changing mechanism connected for response to'pressure in said tubing resultant from a predetermined rate of increase in the temperature of the atmosphere surrounding any portion of said tubing, and means whereby a signal may be initiated by said second mechanism while said receiver is responsive only to control by said transmitter and said transmitter is always re- I sponsive to impairment of the current path which includes said loop.

2. In a fire alarm system, in combination, a

electricity which channel and path extend throughout the area to be protected and comprise a plurality of sections of metallicfire detecting tubing containing a fluid characterized by expansibility responsive to temperature rise such as will displace the fluid along the length of said channel, a hollow member of dielectric material providing a fluid chamber extending said channel between adjacent ends or said sections, a fixed temperature 1nechanism mounted on attainment of a predetermined temperature for impairing the conductivity of said path, electrical 5 insulation enclosing said tubing, signaling mechanism comprising signal-initiating mechanism and a starting magnet therefor, said path forming part of a normally closed shunt around said magnet, means associated with said tubing for actuation by fluid pressure resultant from [a predeterminedrate-of-rise in the temperature of the atmosphere surrounding any portion of said tubing for impairing the conductivity of said shunt, and signal manifesting mechanism responsivcly associated with said signal-initiating mechanism,

3. In a fire alarm system, in combination, a

channel for fluid and a normally closed path for electricity which channel and path extend throughout the area'to be protected and comprise a plurality of sections of metallic fire detecting tubing containing a fluid characterized by expansibility responsive to temperature rise such 'as will displace the fluid along the length of said channel, a hollow member of dielectric materiallproviding 26 a fluid chamber extending said channel between adjacent ends of said sections, a fixed tempera-v ture mechanism mounted on said hollow member extending said path between adjacent ends of said sections and responsive to attainment of 30 a predetermined temperature for impairing the conductivity of said path, signaling mechanism comprising signal-initiating mechanism and a starting magnet therefonsaid'path forming part of a normally closed 'shunt aroundsaid magnet, means associated with said tubing for actuation by fluid pressure resultant from apredeterminedrate-of-rise in the temperature of theatmosphere surrounding any portion of said tubing for iimpairing the conductivity of saidshuntyand i 40 signal manifestingmechanisnr responsively assoof said channel, a member of dielectric material extending said channel between adjacent ends of said sections, a fixed temperature" mechanism mounted on said member extending said path between adjacent ends of said sections and responsive to attainment of a predetermined temperature for impairing the conductivity of said path, signaling mechanism comprising signalinitiating mechanism and a starting magnet therefor, said path forming part of a normally closed shunt around said magnet, means associated with said tubing for actuation by fluid pressure resultant from a predetermined rate-of-rise in the temperature of the atmosphere surrounding any portion of said tubing for impairing the conductivity of said shunt, and signal manifesting mechanism responsively associated with said sig-' nal-initiating mechanism.

5. In a firealarm system, in combination, a channel for fluid and a normally closed path for electricity which channel and path extend throughout the area to be protected and comprise a plurality of sections of metallic fire detecting tubing containing a fluid characterized I by expansibility responsive to temperature rise such as will displace the fluid along the length of said channel, a member of dielectric material extending said channel between adjacent ends of said sections, a fixed temperature mechanism mounted on said member extending said path between adjacent ends of said sections and respon- 5 sive to attainment of a predetermined temperature for impairing the conductivity of said path,

signaling mechanism comprising signal-initiating mechanism and a starting magnet therefor, said path forming part of a normally closed shunt 10 around said magnet, and' means associated with said tubing for actuation by fluid pressure resultant'from a predetermined rate-of-rise in the temperature of the atmosphere surrounding any portion of said tubing for impairing the conducl5 tivity of said shunt.

6. In a fire alarm system, in combination, a channel for fluid and a normally closed path for electricity which channel and path extend throughout the area to be protected and com- 20 prise a plurality of sections of metallic fire detecting tubing containing a fluid characterized by expansibility responsive to temperature rise such as will displace the fluid along the length of said channel, a member of dielectric material 25 extending said channel between adjacent ends of said sections, a fixed temperature" mechanism extending said path between adjacent ends of said sections and responsive to attainment of a predetermined temperature for impairing the 30 conductivity of said path, signaling mechanism comprising signal-initiating mechanism and a starting magnet therefor, said path forming part of a normally closed shunt around said magnet, and means associated with said tubing for ac- 35 tuation by fluid pressure resultant from a predetermined rate-of-rise in the temperature of the atmosphere surrounding any portion of said tubing for impairing the conductivity of said shunt.

'7. In a fire alarm system, in combination, a 40 channel for fluid and a normally closed path for electricity which channel and path extend throughout the area to be protected and comprise a plurality of sections of metallic fire detecting tubing containing a fluid characterized 45 by expansibility responsive to temperature rise such as will displace the fluid along the length of said channel, a hollow member of dielectric material providing a fluid chamber extending said channel between adjacent ends of said sec- 50 tions, a fixed temperature mechanism mounted on said hollow member-extending said path between adjacent ends of said sections and responsive to attainment of a predetermined temperaelectrical insulation enclosing said tubing, signal manifesting mechanism comprising means for response to alteration of the conductivity of said path, and independently acting means for response to fluid displacement in said channel re- 0 sultant from a predetermined rate-of-rise of the temperature of the atmosphere surrounding any ortion of said tubing.

8. In a fire alarm system, in combination, a channel for fluid and a normally closed path for 5 electricity which channel and path extend throughout the area to be protected and comprise a plurality of sections of metallic fire detecting tubing containing a fluid characterized by expansibility responsive to temperature rise such as 70 will displace the fluid along the length of said channel, a hollow member of dielectric material providing a fluid chamber extending said channel between adjacent ends of said sections, a fixed temperature" mechanism mounted on said 1101- 75 sultant from a predetermined rate-of-rise of the temperature of the atmosphere surrounding any portion oi. said tubing.

9. In a fire alarm system, in combination, a channel for fluid and a normally closed path for electricity which channel and path extend throughout the area to be protected and comprise a plurality of sections of metallic fire detecting tubing containing a fluid'characterized by expansibility responsive to temperature rise such as will displace the fluid along the length of said channel, a member of dielectric material extending said channel between adjacent ends of said sections, a fixed temperature mechanism mounted on said member extending said path between adjacent ends of said sections and responsive to attainment of a predetermined temperature for altering the conductivity of said path, signal manifesting mechanism comprising means for response to alteration of the conductivity of said path, and independently acting means for response to fluid displacement in said channel resultant from a predetermined 'rate-of-rise of the temperature of the atmosphere surrounding any portion of said tubing.

10. In a fire alarm system, in combination, a channel for fiuid and a normally closed path for electricity which channel and path extend throughout the area to be protected and comprise a plurality of sections of metallic fire detecting tubing containing a fluid characterized by expansibility responsive to temperature rise such as will displace the fluid along the length of said channel, a member of dielectric material extending said channel between adjacent ends of said sections, a fixed temperature mechanism extending said path between adjacent ends of said sections and responsive to attainment of a predetermined temperature for altering the conductivity of said path, signal manifesting mechanism comprising means for response to alteration of the conductivity of said path, and independently acting means for response to fluid displacement in said channel resultant from a predetermined rate-of-rise of the temperature of the atmosphere surrounding any portion of said tubing.

11; In a fire alarm system, in combination, a channel for fluid and a normally closed path for electricity which channel and path extend throughout the area to .be protected and comprise a plurality of sections of metallic fire detecting tubing containing a fluid characterized by expansibility responsive to temperature rise such as will displace the fluid along the length of said channel, a hollow member of dielectric material providing a fluid chamber extending said channel between adjacent ends of said sections, a fixed temperature mechanism mounted on said hollow member extending said path between adja'cent ends of said'sections and responsive to attainment ofv a predetermined temperature for altering the conductivity of said path, electrical insulation enclosing said tubing, and signal manifesting mechanism comprising means for response both to alteration of the conductivity of said path :and to fluid displacement in said channel resultant irom a predetermined rate-of-rlse of the temperature of the atmosphere surounding any portion of said tubing.

12. In a fire alarm system, in combination, a

channel for fluid and a normally closed 'path for electricity which channel and path extend throughout the area to be protected and comprise a plurality of sections of metallic fire detecting tubing containing a fluid characterized by expansibility responsive to temperature rise such as will displace the fluid along the length of said channel, a hollow member of dielectric material providing a fluid chamber extending said channel between adjacent ends of said sections, a fixed temperature mechanism mounted on said hollow ,member extending said path between adjacent throughout the area to'be protected and com-- prise a plurality of sections of .metallic fire detecting tubing containing a fluid characterized by expansibility responsive to temperature rise such] as will displace the fluid along the length of said channel, a member of dielectric material extending said channel between adjacent ends of said sections, a fixed temperature mechanism mounted on said member extending said path between adjacent ends 01' said sections and responsive to attainment of a predetermined temperature for altering the conductivity of said path, and signal manifesting mechanism com- 7 prising means for response both to' alteration of the conductivity of said path and to fluid displacement in said channel resultant from a predetermined rate-of-rise of the temperature of the atmosphere surrounding any portion 01' said tubing.

14. In a flre alarm system, in combination, a

channel for fluid and a normally closed path for electricity which channel and path extend throughout the area to be protected and com-- prise a plurality of sections of metallic fire detecting tubing containing a fluid characterized by as will displace the fluid alongthe length of said channel, a. member'of dielectric material extendexpansibility responsive to temperature rise such ing said channel between adjacent ends of said sections,-a fixed temperature" mechanism extending said path between adjacent ends of said sections and responsive to attainment of a predetermined temperaturefor altering the conductivity of said path, and signal manifesting mecha: nism comprising means for response both to alteration of the conductivity of said path'and to fluid displacement in said channel resultant from a predetermined rate-of-rise oi the temperature of the atmosphere surrounding any portion of said tubing.

15. In a fire alarm system, in combination, a

conduit for fluid and a normally closed path for.

electricity which conduit and path extend throughout the area to be protected and comprise a plurality of sections of metallic flre detecting tubing connected together with their ends in electrically insulated relation to form a continuous conduit for fluid, said conduit contain ing a fluid characterized by expansibility responsive to temperature rise such as will displace the fluid along the length of said conduit, fixed temperature mechanisms electrically connecting adjacent ends of said sections for normally establishing a current path through and between adjacent sections and responsive to attainment of a predetermined temperature for altering the conductivity of said path, electrical insulation enclosing said tubing, signal manifesting mechanism comprising means for response both to alteration oi the conductivity of said path and to fluid displacement in said conduit resultant from apredetermined rate-of-rise of the temperature of the atmosphere surrounding any portion of said tubing.

g 16. In a fire alarm system, in combination, a conduit for fluid and a normally closed path for electricity which conduit and path. extend throughout the area to be protected and comprise a plurality of sections of metallic fire detecting tubing connected together with their ends in electrically insulated relation to form a continuous conduit for fluid, said conduit containing a fluid characterized by expansibility responsive to temperature rise such as will displace the fluid along the length of said conduit, fixed temperature mechanisms electrically connecting adjacent ends of said sections for normally establishing a current path through and between adjacent sections and responsive to attainment 01' a predetermined temperature for altering the conductivity of said path, and signal manifesting mechanism comprising means for response both to alteration of the conductivity of said path and to fluid displacement in said conduit resultant from a predetermined rate-of-rise of the tem- 5 perature of the atmosphere surrounding any portion of said tubing.

17. In a fire alarm system, means for manifesting signals responsive both to the attainment of predetermined temperature and to more than 10 a predetermined rate 0! temperature rise, said means comprising "flxed temperature mechanism for altering the conductivity of a normally closed circuit responsive to attainment of a predetermined temperature, and rate-oi-rise-flre l6 detecting mechanism including tubing, which tubing serves as an electrical conductor between said circuit altering-mechanism and said signal manifesting means, and electrical insulation enclosing said tubing.-

18. In a fire alarm system, means for manifesting signals responsive both to the attainment of predetermined temperature and to more than a predetermined rate of temperature rise, said means comprising fixed temperature mech- 25 anism for altering the conductivity of a normally closed circuit responsive to attainment of a predetermined temperature, and rate-oi-rise" fire detecting'mechanism including tubing, which tubing serves as an electrical conductor between 30 said circuit altering mechanism and said signal manifesting means.

WILLIAM M. SIDDALL, JR.