US 5,207,276 AGranted

Wire-sensored fire extinguisher with fault-monitoring control system

AssigneePem All Fire Extinguisher Corporation

InventorWilliam A. Scofield

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Abstract

A range hood positioned above a cooking range employs a continuous heat sensor system which includes twisted wires which are separated from one another by an insulator which is formed of a material which melts at a predetermined temperature. The wires carry a supervisory current which is monitored continuously. When the magnitude of the current is increased, such as by the creation of a short-circuit condition as would be caused by the presence of a fire, an actuation signal is issued to an actuator, which may include an explosive squib. The explosive squib releases a tension wire which holds a discharge valve in a closed position, permitting a fire suppressant fluid to be discharged from a supply tank. Monitor circuitry ensures that open-circuit or short-circuit faults do not disable the functioning of the actuation system. Multi-condition fault indicators alert the user visually and audibly of system faults.

Claims19

Dependent claims

A system for protecting a predetermined region from a fire which may occur therein, the system comprising:

fire suppressant supply means for containing a quantity of pressurized fire suppressant material;
actuatable discharge means for releasing said quantity of pressurized fire suppressant material upon actuation of said actuatable discharge means;
sensor means arranged in the vicinity of the predetermined region, said sensor means having an electrical characteristic which changes in response to heat in the protected region, said sensor means having:
first and second conductors;
a supervisory electrical current flowing through said first and second conductors;
conductor separation means having a predetermined heat response characteristic whereby said first and second conductors are maintained electrically insulated from one another below a predetermined temperature, and are brought into electrical communication with one another when said predetermined temperature is exceeded to produce a reduced electrical impedance characteristic across said first and second conductors and a corresponding increase in the magnitude of said supervisory electrical current;
sensor monitor means for monitoring said supervisory electrical current, and for signalling an increase in the magnitude thereof;
and
trigger means responsive to said signalling of said sensor monitor means for actuating said actuatable discharge means.

6 more elements

A system for producing an activation signal responsive to the presence of a fire which may occur within a predetermined region, the system comprising:

hood means arranged to overlie the protected region, said hood means having a top wall, first and second side walls, and a front wall;
first and second conductors for carrying a supervisory electrical current, said first and second conductors being arranged and supported beneath said hood means so as to be intermediate of said hood means and the protected region;
conductor separation means having a predetermined heat response characteristic whereby said first and second conductors are maintained electrically insulated from one another below a predetermined temperature, and are brought into electrical communication with one another when said predetermined temperature is exceeded to produce a substantially short-circuit condition across said first and second conductors and a corresponding increase in the magnitude of said supervisory electrical current;
sensor monitor means having inactivated and activated states responsive to an activation current threshold characteristic which is intermediate of a low supervisory electrical current value which flows through said first and second conductors, and a high supervisory electrical current value which flows through a low impedance condition produced when said first and second conductors are brought into electrical communications with one another, said sensor monitor means further having an electrical output for producing the activation signal in response to said activated state;
activator means for issuing an electric signal in response to said sensor monitor means;
and
activator monitor means for detecting a fault condition in said activator means.

4 more elements

Dependencies are inferred from the claim text.