FIRE ALARM Russian patent published in 2015 - IPC G08B17/06 

FIELD: physics, signalling.

SUBSTANCE: invention relates to fire alarm devices which are activated by the heat effect of a fire source and is intended for use in systems for distributed monitoring of extended fire hazardous facilities. The fire alarm comprises a sensitive element, a first electroacoustic transducer, an electric oscillation generator, a second electroacoustic transducer, an amplifier, an amplitude detector, an integrator, a threshold device, a unit for indicating presence of a fire and an acoustic resonator. The sensitive element is an extended heat-resistant acoustic waveguide, connected by the input to the output of the first electroacoustic transducer. The input of the first electroacoustic transducer is connected to the output of the electric oscillation generator. The second electroacoustic transducer is connected by the output to the input of the amplifier. The output of the amplifier is connected through the series-connected amplitude detector, integrator and threshold device to the input of the unit for indicating presence of a fire. The input of the acoustic resonator is interfaced with the sensitive element by a mechanical link at the area located between the output of the first electroacoustic transducer and the working area of the sensitive element. The output of the acoustic resonator is interfaced by an acoustic link to the input of the second electroacoustic transducer.

EFFECT: easy installation of the alarm at a monitored facility and high reliability of signalling.

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