US2946989A - Temperature indicator and fire alarm system - Google Patents
Temperature indicator and fire alarm system Download PDFInfo
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- US2946989A US2946989A US462992A US46299254A US2946989A US 2946989 A US2946989 A US 2946989A US 462992 A US462992 A US 462992A US 46299254 A US46299254 A US 46299254A US 2946989 A US2946989 A US 2946989A
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- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B17/00—Fire alarms; Alarms responsive to explosion
- G08B17/06—Electric actuation of the alarm, e.g. using a thermally-operated switch
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- the present invention is related to the novel combination of two normally independent systems and more particularly relates to the combination of a temperature indicating system and a fire detection and alarm system.
- Another object is to provide a temperature indicating and tire detection and alarm system of an economical nature by the joint use of electrical conductors from the indicator station to the remote temperature sensing and fire detection means.
- Figure l sets forth in block diagram a Y simple system utilizing my invention, wherein, the system shown has a single monitored location.
- Figure 2 discloses a schematic arrangement of a system having a plurality of remote indicator locations in standby condition and with no fire existing.
- a temperature indicating system and-a fire alarm system are shown combined in a single indicator unit 10.
- To this unit is connected by a plurality of electrical cables 11a, 11b and 11e remote units 14a, 14h and 14C, respectively each of which contains both a temperature sensing device and a iire detection device.
- the unit 10 could be separated into two units, a temperature indicating system and a fire alarm system, and that they could be inter-related by the appropriate wiring. lf this is done however, a single three circuit cable from each remote unit would still be used so that joint use by both systems of conductive means of the cable would be possible.
- FIG. 2 A schematic diagram of this disclosure is shown in Figure 2. While three remote monitored locations are shown generally at 14a, 14b, and 14e it is understood that any number may be used and that they would be connected in a manner similar to those shown. Since all of the remote monitored locations 14a, 14b, and 14C are of the same construction the discussion in this disclosure will be limited to the elements of location 14a, but similar numbers will indicate identical parts and subletters will be used to ditfentiate between remote locations.
- the remote monitored location 14a is made up, in part, of a temperature sensitive resistor 15a.
- the resistor may be made of a temperature responsive resistance wire such as Balco wire wound on a plastic bobbin or support, or in any other mannerwhich is convenient, such methods being well understood by those versed in the art.
- Resistor 15a has one of its ends connected directly to one end of a fusible iire detection element 16a.
- Element 16a is composed of a low melting alloy and the selection of the alloy and the configuration of the element is dependent on the temperature to be protected against. It is understood that the proper selection of a fire detection element 16a is also well known to those versed in the art.
- resistor 15a The free end of resistor 15a, the junction of resistor 15a and ire detection element 16a, and the free end of fire detection element 16a are connected to three lead wires 17a, 18a, and 19a. These three lead wires cor-V respond to cable 11 shown in Figure l and provide-the means'of interconnecting the remote monitored location 14a (shown generally in Figure l as at 12) and, the system indicator unit (shown generally at 10 in Figure l).
- Lead wires 17a, 18a, and 19a connect to Vthree poles 23a, 24a, and 25a of a four pole switch 22a which is part of the combined indicator unit shown generally at 10 and which consists of the remainder of Figure 2. It should be noted that the indicator unit generally shown at 10 in Figure 1 corresponds to indicator unit 10 in Figure 2.
- the indicator system 20 With the switches 22a, 2211, and 22e in the position shown in Figure 2 the indicator system 20 is in standby Y condition and no fire conditions exist.
- the tire alarm circuit consists of a series combination of power supply 33, conductor 34, switch 261;, conductor 35, switch 26C, conductor 36, relay contacts 37 of a relay generally shown at 38, conductor 39, switch 26a, conductor 30, fire alarm bell 31, and conductor 32. It is apparent from this circuit that the fire alarm bell 31 will ring when contacts 37 of relay 38 are closed.
- Relay 38 consists of a U-shaped core 41 on which a primary coil 42 and a secondary coil 43 are4 wound. Energization of coil 42 is supplied by an alternating current source 44 through conductor 45, capacitor 46, conductor 47, and conductor 48. The size of capacitor 46 is selected to resonate the circuit of coil 42 when coil 43 is open circuited. Under the conditions of secondary coil 43 being open circuited and the circuit of primary coil 42 being resonated by capacitor 46, the armature 49 of relay 38 is pulled in against the bias of spring'50 and contacts 37 close.
- the circuit is opened by melting of one of the fire detection elements 16a, 16b, or 16C.
- neon glow bulbs (of commercially available design) 65a, 65h, and 65C are connected in parallel with ire detection elements 16a,'16b, and 16C.
- neon glow bulb 65a is caused to conduct and glows to indicate that fire de- The glow bulb 65a, howis pushed to the right.
- Switches 22a, 22b, and 22e ⁇ arey spring biased to the left (the means for biasing them s not shown) and they return to this position except when moved to obtain a temperature reading. For example, if the temperature at 14a is desired, switch 22a is moved ter-fthe right. -Fhis disables the fire alarm system by opening 26a. It also switches the conductors ft/alga, and
- the three wire bridge type temperature indicating system' is-o'f a well known type and could be similar to' that disclosed in' Patent 1,097,651.
- this type of bridge system' two conductors are connected together to form one connection to the sensing element while a Vthird wire is connected to the other sideot the sensing element. This is done to' provide for temperature compensation in the connection means and allows the sensing element 'to be located at any convenient distance from the bridge without concern for errors due to changes of temperature in the' areas the conductors pass through.
- the bridge sys'- tern consists of a direct current power supply 70 which derives its input power from alternating current source f4? and conductors 45, 71, 47, Vand 48. Th'e direct current-output is supplied to conductors 72 and 73. Cond'uctor 72 in turn ⁇ is connected to one end of balancing potentiometer# and is adjusted by changing the position of slider 76 which is grounded at 78. The conducto'r 73' is connected through resistors 79 and 80, balancing potentiometer 75., and slider 77 to ground 78.
- the reading of the temperature at the selected remote location is obtained by the unbalance of a bridge and is indicated on a direct current meter movement calibrated as a temperature indicator 82.
- the temperature indicator 82 determines the nnbalance'of the bridge and is connected across the bridge from the junction of resistor 79 and 80 by conductor 8S, and" by conductors 84, 86a, switch 24a, conductor 18a,to the junction of the resistance sensitive element 15a and tirelire detection element 16a. It is apparent from the above discussion that it is possible to determine the temperature at any of the remote locations by depressing the proper selector switch and then reading the temperature directly from the temperature indicator. This novel unit also provides for almost constant supervision of the remote locations for possible nre and indicates by neon glow bulb, the location or locations of Vany firesv that do exist.'
- a plurality of remotely located temperature responsive units each including a temperature sensitive resistance indicative of temperature and a temperature responsive switch element actuated when the temperature of said switch element exceeds a predetermined temperature, az selectively operable switching meansfor each of said temperature responsive units and having a 'rst normalrpositionan'dY a' second position, a central electrical energy, responsivetemperature indicating means, a central alarm means, a plurality of first conductors each connected to one terminal of a different one of said switch elements and to the associated switching means, a similar plurality of second conductors each connected to the opposite terminal of a different one of said switch elements and to the associated switching means, a control circuit for said alarm means including said plurality of switching means and effective when said switching means are all in their Yfirst normal position to.connect said plurality of first and second conductors and the temperature responsive switching elements to said alarrnmeans, said control circuit being operative to render said alarm effective upon any of said temperature sensitive
- a plurality of remotely located temperature responsive units each including a temperature sensitive resistance indicative of temperature and a temperature responsive switch element providing an open circuit when the temperature of said switch element exceeds a predetermined temperature, a selectively operable switching means for each of said temperature responsive units and having a first normal position and a second position, a central temperature indicating means, a central alarm means, a plurality of first conductors each connected to one terminal of a dilerent one of said switch elements and to the associated switching means, a similar plurality of second conductors each connected to the opposite terminal of a different one of said switch elements and to the associated switching means, a control circuit for said alarm means including said plurality of switchingl means and effective when said switching means are all in their first normal position to connect said plurality of firstand second conductors and the temperature responsive switching elements all in series with each other and to said alarm means, said control circuit being operative to render said alarm effective upon said circuit being interrupted by the opening of any of said temperature sensitive switch elements, a plurality of remotely located temperature responsive units each including a temperature
- a plurality of remotely located temperature responsive units each including a temperature sensitive resistanceindica'tive of temperature and a temperature responsive switch element providing an open circuit when the temperature of said switch element exceeds a predetermined'temperature, alikev plurality o'f selectively operable switching means located together at a central point remote from said units, there being one of said switching means for each of said temperature responsive units and each switching means having a first normal position and a second position, a temperature measuring bridge also remotely located from said temperature respo'nsive unit and having a central temperature indicating means between the output terminals of the bridge and in proximity to said switching means, a central alarm means, a plurality of first conductors each connected to one terminal of a diierent one of said switch elements and to the associated switching means, a similar plurality of second co'nductors each connected to the opposite terminal of a diierent one of said switch elements and to the associated switching means, a control circuit for said alarm means including said plurality of switching means and effective
- a temperature responsive unit including a temperature sensitive resistance indicative of temperature and a temperature responsive switch element providing 'an open circuit when the temperature of said switch element exceeds a predetermined temperature, a selectively operable switching means remotely located from said temperature responsive unit having a rst normal position and a second position, a temperature measuring resistance bridge also remotely located from said temperature responsive unit and having a temperature indicating means between the ouput terminals of the bridge, an alarm means, rst and ⁇ second conductors connected to oppo'site terminals of said switch elements and to said switching means, said second conductor being connected to one terminal of said temperature sensitive resistance, a third conductor connected to the opposite terminal of said temperature sensitive resistance and to said switching means, a control circuit for said alarm means including said switching means and effective when said switching means is in its lirst normal position to connect said first and second conductors and the temperature responsive switching element in a closed circuit to said alarm means, said control circuit being operative to render said alarm effective upon said circuit being
Description
July 26, 1960 J. A. LOEBER 2,946,989
TEMPERATURE INDICATOR ANO ETRE ALARM SYSTEM Filed oct. 18, 1954 IO P- .F/. l TEINIgETATMgE FIRE ALARM SYSTEM SYSTEM |I0L` l !llb I |Ic-" A l I l REMOTE REMOTE J2 REMOTE MONITOREO MONITOREO MONITOREO LOCATION LOOATION A LOCATION I4u I4b 14e f FIRE 3| Fl 2 ALARM 3? l 3o BELL 32 I I EIEIIBEE FusIBLE ELEMENT 34 SUPPLY )1 .f- TR-3) L 5s` 57` I 59\ 6O\ I l l 65h I esc 55 1 5B 85e 1 87a 7b '-1 gn: 'J -eeb -sse Io 83 To 7| I 72 74 l o c 8f' POwER 76 JW/[NW 45T ;47 SUPPLY -'TS 77 so 88 8,2 lv' 5 TEMDR 4s I I om .l 79 84 INVENTOR JOHN A. LOEBER /EMW f M BY ATTORNEY Pai-@nies .inlypza 1960 TEMPERATURE INDICATOR 'AND FIRE ALARM SYSTEM John A. Loenen, Minneapolis, Minn., assigner to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Filed Oct. I13, 17954, Ser. No. 462,992
`4 Claims. (Cl. S40- 181) The present invention is related to the novel combination of two normally independent systems and more particularly relates to the combination of a temperature indicating system and a lire detection and alarm system.
It is an object of this invention to provide a system that is capable of monitoring a plurality of locations from one indicator station so that constant supervision of temperature and other conditions can be maintained.
Another object is to provide a temperature indicating and tire detection and alarm system of an economical nature by the joint use of electrical conductors from the indicator station to the remote temperature sensing and lire detection means.
These and other objects will become apparent kfrom readingthe following disclosure when considered with the attached single sheet of drawings. Y
In the drawings, Figure l sets forth in block diagram a Y simple system utilizing my invention, wherein, the system shown has a single monitored location. Figure 2 discloses a schematic arrangement of a system having a plurality of remote indicator locations in standby condition and with no lire existing.
In Figure l a temperature indicating system and-a lire alarm system are shown combined in a single indicator unit 10. To this unit is connected by a plurality of electrical cables 11a, 11b and 11e remote units 14a, 14h and 14C, respectively each of which contains both a temperature sensing device and a iire detection device. It should be understood that the unit 10 could be separated into two units, a temperature indicating system and a lire alarm system, and that they could be inter-related by the appropriate wiring. lf this is done however, a single three circuit cable from each remote unit would still be used so that joint use by both systems of conductive means of the cable would be possible. Y
A schematic diagram of this disclosure is shown in Figure 2. While three remote monitored locations are shown generally at 14a, 14b, and 14e it is understood that any number may be used and that they would be connected in a manner similar to those shown. Since all of the remote monitored locations 14a, 14b, and 14C are of the same construction the discussion in this disclosure will be limited to the elements of location 14a, but similar numbers will indicate identical parts and subletters will be used to ditfentiate between remote locations.
The remote monitored location 14a is made up, in part, of a temperature sensitive resistor 15a. The resistor may be made of a temperature responsive resistance wire such as Balco wire wound on a plastic bobbin or support, or in any other mannerwhich is convenient, such methods being well understood by those versed in the art. Resistor 15a has one of its ends connected directly to one end of a fusible iire detection element 16a. Element 16a is composed of a low melting alloy and the selection of the alloy and the configuration of the element is dependent on the temperature to be protected against. It is understood that the proper selection of a lire detection element 16a is also well known to those versed in the art.
The free end of resistor 15a, the junction of resistor 15a and ire detection element 16a, and the free end of lire detection element 16a are connected to three lead wires 17a, 18a, and 19a. These three lead wires cor-V respond to cable 11 shown in Figure l and provide-the means'of interconnecting the remote monitored location 14a (shown generally in Figure l as at 12) and, the system indicator unit (shown generally at 10 in Figure l).
Lead wires 17a, 18a, and 19a connect to Vthree poles 23a, 24a, and 25a of a four pole switch 22a which is part of the combined indicator unit shown generally at 10 and which consists of the remainder of Figure 2. It should be noted that the indicator unit generally shown at 10 in Figure 1 corresponds to indicator unit 10 in Figure 2.
With the switches 22a, 2211, and 22e in the position shown in Figure 2 the indicator system 20 is in standby Y condition and no fire conditions exist. In this case the tire alarm circuit consists of a series combination of power supply 33, conductor 34, switch 261;, conductor 35, switch 26C, conductor 36, relay contacts 37 of a relay generally shown at 38, conductor 39, switch 26a, conductor 30, fire alarm bell 31, and conductor 32. It is apparent from this circuit that the fire alarm bell 31 will ring when contacts 37 of relay 38 are closed.
' Relay 38 consists of a U-shaped core 41 on which a primary coil 42 and a secondary coil 43 are4 wound. Energization of coil 42 is supplied by an alternating current source 44 through conductor 45, capacitor 46, conductor 47, and conductor 48. The size of capacitor 46 is selected to resonate the circuit of coil 42 when coil 43 is open circuited. Under the conditions of secondary coil 43 being open circuited and the circuit of primary coil 42 being resonated by capacitor 46, the armature 49 of relay 38 is pulled in against the bias of spring'50 and contacts 37 close. When coil 43 is short circuited, the change in limpedance reected into the primary circuit of coil 42 by transformer action detunes the resonant conditions existing in the primary circuit and the armature 49 of relay 38 is pulled to the position vshown in Figure 2 by the spring 50 and therefore opens contacts 37. It will be appreciated therefore, that the series standby circuit from coil 43 to conductors 52, 53, pole 24a, conductor 18a, lire detection unit 16a, conductor 19a, pole 25a, conductors S4, 55, 56, pole 24b, conductor 18b, iire detection element 16h, conductor 19b, pole 25h, conductors 57, 58, 5.9, pole 24C, conductor 18C, fire detection element 16C, conductor 19C, pole 25e, conductors 60, 61 and back to coil 43 form a short circuit for coil 43 of relay 38. This short circuit causes contacts 37 to `tection element 16a, is open. ever, does not pass enough current to hold relay 38 open i be held open by action of. spring 50. If tire occurs at any of the iire detection locations the circuit is opened by melting of one of the fire detection elements 16a, 16b, or 16C. It should be further pointed out that neon glow bulbs (of commercially available design) 65a, 65h, and 65C are connected in parallel with ire detection elements 16a,'16b, and 16C. Upon opening of the circuit at iire detection element 16a, for example, neon glow bulb 65a is caused to conduct and glows to indicate that lire de- The glow bulb 65a, howis pushed to the right. Switches 22a, 22b, and 22e` arey spring biased to the left (the means for biasing them s not shown) and they return to this position except when moved to obtain a temperature reading. For example, if the temperature at 14a is desired, switch 22a is moved ter-fthe right. -Fhis disables the fire alarm system by opening 26a. It also switches the conductors ft/alga, and
1921 of th'e connecting means from the fire al'arrn circuit to afthree wire bridge type temperature indicating system. The three wire bridge type temperature indicating system' is-o'f a well known type and could be similar to' that disclosed in' Patent 1,097,651. In this type of bridge system' two conductors are connected together to form one connection to the sensing element while a Vthird wire is connected to the other sideot the sensing element. This is done to' provide for temperature compensation in the connection means and allows the sensing element 'to be located at any convenient distance from the bridge without concern for errors due to changes of temperature in the' areas the conductors pass through. The bridge sys'- tern consists of a direct current power supply 70 which derives its input power from alternating current source f4? and conductors 45, 71, 47, Vand 48. Th'e direct current-output is supplied to conductors 72 and 73. Cond'uctor 72 in turn `is connected to one end of balancing potentiometer# and is adjusted by changing the position of slider 76 which is grounded at 78. The conducto'r 73' is connected through resistors 79 and 80, balancing potentiometer 75., and slider 77 to ground 78. The actual resistances that form the bridge of the 'indicating system 'are resistors 81, the part of potentiometer 75 connected between resistor 81 and resistor 80, resistor 80 itself, resistor V79`, and the resistor in the remote monitored' location that is selected by switch 22a, 22`b, or 22C. The reading of the temperature at the selected remote location is obtained by the unbalance of a bridge and is indicated on a direct current meter movement calibrated as a temperature indicator 82. Conductors 73, 83, and 84 in`- combination with lead wires 85a, 85h, 85e, 86a, 8`6b, 86C, 87a, 87b, and 87C. provide the necessary intercommunication between the main bridge elements and the switchesV 22a', 221:, and 22C to the remote monitor locations, When switch 22a is moved to the right the cornpl'e't'e bridge circuit can be traced from slider I7 to resistorS-I, conductors 83, 87a, switch 25a conductor19iz, element- 16a, resistor 15a, conductor 17a, switch 23a, conductors 85a, 73, resisor 79, resistor 80, and potentiometer 75. The temperature indicator 82 determines the nnbalance'of the bridge and is connected across the bridge from the junction of resistor 79 and 80 by conductor 8S, and" by conductors 84, 86a, switch 24a, conductor 18a,to the junction of the resistance sensitive element 15a and tirelire detection element 16a. It is apparent from the above discussion that it is possible to determine the temperature at any of the remote locations by depressing the proper selector switch and then reading the temperature directly from the temperature indicator. This novel unit also provides for almost constant supervision of the remote locations for possible nre and indicates by neon glow bulb, the location or locations of Vany liresv that do exist.'
The disclosure above has been cited as an example only ofone possible means of carrying out my invention and Ido not'wish to be limited to it alone. I limit my invention only to' the scope of the appended claims.
I claim as my invention:
1'. In a combined temperature indicating and fire alarm'system, a plurality of remotely located temperature responsive units each including a temperature sensitive resistance indicative of temperature and a temperature responsive switch element actuated when the temperature of said switch element exceeds a predetermined temperature, az selectively operable switching meansfor each of said temperature responsive units and having a 'rst normalrpositionan'dY a' second position, a central electrical energy, responsivetemperature indicating means, a central alarm means, a plurality of first conductors each connected to one terminal of a different one of said switch elements and to the associated switching means, a similar plurality of second conductors each connected to the opposite terminal of a different one of said switch elements and to the associated switching means, a control circuit for said alarm means including said plurality of switching means and effective when said switching means are all in their Yfirst normal position to.connect said plurality of first and second conductors and the temperature responsive switching elements to said alarrnmeans, said control circuit being operative to render said alarm effective upon any of said temperature sensitive switch elements being actuated upon its temperature exceeding said predetermined value, a plurality of third conductors each connected to one terminal of a different one of said resistances and to the associated switching means, each of said second conductors being connected to the other terminal of a different one of said resistances, and circuit means controlled by said switching means operable upon any one of said switching means being moved to its second position to connect the second and third conductors connected to the associated resistance to said temperature indicating means to cause the latter to indicate the temperature at the area in which said resistance unit is located and to cause said third conductor of the associated temperature responsive switch element to be connected to said temperature indicating means in such a manner as to oppose the effect of the resistance of said first conductor.
2. In a combined temperature indicating and fire alarm system, a plurality of remotely located temperature responsive units each including a temperature sensitive resistance indicative of temperature and a temperature responsive switch element providing an open circuit when the temperature of said switch element exceeds a predetermined temperature, a selectively operable switching means for each of said temperature responsive units and having a first normal position and a second position, a central temperature indicating means, a central alarm means, a plurality of first conductors each connected to one terminal of a dilerent one of said switch elements and to the associated switching means, a similar plurality of second conductors each connected to the opposite terminal of a different one of said switch elements and to the associated switching means, a control circuit for said alarm means including said plurality of switchingl means and effective when said switching means are all in their first normal position to connect said plurality of firstand second conductors and the temperature responsive switching elements all in series with each other and to said alarm means, said control circuit being operative to render said alarm effective upon said circuit being interrupted by the opening of any of said temperature sensitive switch elements, a plurality of third conductors each connected to one terminal of a dilferent one of said resistances and to the associated switching means, each' of said seco'nd conductors being connected to the other terminal of a different one of said resistance elements, and circuit means controlled by said switching means operable upon any one of said switching means being moved to its second position to render said alarm means inelective while said switching means is in said second position and to connect the second and third conductors connected to the associated resistance to said temperature indicating means to cause the latter to indicate the temperature at` the area in which said resistance unit is located.
3.. In a combined temperature indicating and tire alarm system, a plurality of remotely located temperature responsive units each including a temperature sensitive resistanceindica'tive of temperature and a temperature responsive switch element providing an open circuit when the temperature of said switch element exceeds a predetermined'temperature, alikev plurality o'f selectively operable switching means located together at a central point remote from said units, there being one of said switching means for each of said temperature responsive units and each switching means having a first normal position and a second position, a temperature measuring bridge also remotely located from said temperature respo'nsive unit and having a central temperature indicating means between the output terminals of the bridge and in proximity to said switching means, a central alarm means, a plurality of first conductors each connected to one terminal of a diierent one of said switch elements and to the associated switching means, a similar plurality of second co'nductors each connected to the opposite terminal of a diierent one of said switch elements and to the associated switching means, a control circuit for said alarm means including said plurality of switching means and effective when said switching means are all in their rst normal position to connect said plurality of iirst and second conductors and the temperature responsive switching elements all in series with each other and to said alarm means, said control circuit being operative to render said alarm eiective upon said circuit being interrupted by the opening of any of said temperature sensitive switch elements, a plurality of third conductors each connected to one terminal of a dilerent one of said resistances and to the associated switching means, each of said second conductors being connected td the other terminal of a different one of said resistances, and circuit means controlled by said switching means operable upon any one of said switching means being moved to its second position to render said alarm means ineffective while said switching means is in said secdnd position and to connect the second and third conductors connected to the associated resistance to said bridge to form one arm thereof and to connect the rst conductor connected to the associated temperature responsive switch element into an opposing arm of said bridge whereby the resistance of said rst conductor compensates for the resistance of said third conductor to enable said bridge to accurately indicate the temperature sensed by said temperature sensing resistance.
4. In a combined temperature indicating and lire alarm system, a temperature responsive unit including a temperature sensitive resistance indicative of temperature and a temperature responsive switch element providing 'an open circuit when the temperature of said switch element exceeds a predetermined temperature, a selectively operable switching means remotely located from said temperature responsive unit having a rst normal position and a second position, a temperature measuring resistance bridge also remotely located from said temperature responsive unit and having a temperature indicating means between the ouput terminals of the bridge, an alarm means, rst and `second conductors connected to oppo'site terminals of said switch elements and to said switching means, said second conductor being connected to one terminal of said temperature sensitive resistance, a third conductor connected to the opposite terminal of said temperature sensitive resistance and to said switching means, a control circuit for said alarm means including said switching means and effective when said switching means is in its lirst normal position to connect said first and second conductors and the temperature responsive switching element in a closed circuit to said alarm means, said control circuit being operative to render said alarm effective upon said circuit being interrupted by the opening of said temperature sensitive switch element, and circuit means controlled by said switching means operable upon any one of said switching means being moved to its second position to render said alarm means ineiective while said switching means is in said second position and to connect the second and third conductors connected to the associated resistance to said bridge to form one arm thereor` and to connect said first conductor thrdugh said temperature responsive switch element into an opposing arm of said bridge whereby the resistance of said first conductor compensates for the resistance of said third conductor to enable said bridge to accurately indicate the temperature sensed by said temperature sensitive resistance.
References Cited in the ijle of this patent UNITED STATES PATENTS 1,965,730 Mason July 17, 1934 2,028,653 Ekman Jan. 21, 1936 2,412,881 Fulton Dec. 17, 1946 2,564,294 Belcher Aug. 14, 1951 2,578,447 Odell et al. Dec. 11, 1951 2,699,675 Buck Jan. 18, 1955
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US462992A US2946989A (en) | 1954-10-18 | 1954-10-18 | Temperature indicator and fire alarm system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US462992A US2946989A (en) | 1954-10-18 | 1954-10-18 | Temperature indicator and fire alarm system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US2946989A true US2946989A (en) | 1960-07-26 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US462992A Expired - Lifetime US2946989A (en) | 1954-10-18 | 1954-10-18 | Temperature indicator and fire alarm system |
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| US (1) | US2946989A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2981938A (en) * | 1955-12-21 | 1961-04-25 | Petcar Res Corp | Combined overheat and flame detector system |
| US3082412A (en) * | 1959-04-07 | 1963-03-19 | Isi Inc | Variable monitoring system |
| US3277457A (en) * | 1963-10-07 | 1966-10-04 | Herman Leon | Automatic signaling system |
| US3407400A (en) * | 1965-08-20 | 1968-10-22 | Eli M. Lurie | Theft control system |
| US3439357A (en) * | 1965-11-12 | 1969-04-15 | Leonidas Gil De Gibaja | Detection systems |
| US3643244A (en) * | 1969-05-26 | 1972-02-15 | Marvin J Levy | Fire and smoke monitoring and alarm system |
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| US2699675A (en) * | 1950-03-06 | 1955-01-18 | Socony Vacuum Oil Co Inc | Two-conductor system for measuring rate and direction of flow and conductivity of fluid in a passage |
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|---|---|---|---|---|
| US2981938A (en) * | 1955-12-21 | 1961-04-25 | Petcar Res Corp | Combined overheat and flame detector system |
| US3082412A (en) * | 1959-04-07 | 1963-03-19 | Isi Inc | Variable monitoring system |
| US3277457A (en) * | 1963-10-07 | 1966-10-04 | Herman Leon | Automatic signaling system |
| US3407400A (en) * | 1965-08-20 | 1968-10-22 | Eli M. Lurie | Theft control system |
| US3439357A (en) * | 1965-11-12 | 1969-04-15 | Leonidas Gil De Gibaja | Detection systems |
| US3643244A (en) * | 1969-05-26 | 1972-02-15 | Marvin J Levy | Fire and smoke monitoring and alarm system |
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