Graviner Limited

Nicholas S Allen

Peter E Moore

A fire or explosion detection arrangement has a housing with first and second adjacent radiation-transmitting windows. The first window includes a filter having a passband corresponding to a narrow predetermined wavelength band. A radiation sensor mounted within the housing receives radiation from a fire or explosion through the first window, the predetermined passband corresponding to a wavelength band within which a fire or explosion to be detected generates radiation. An external source generates testing radiation having wavelengths capable of passing through the second radiation transmitting window but not through the filter. This radiation is directed to the sensor. There, means (either the sensor itself or, for example, an FET which is provided to process the normal output of the sensor) responds to the level of the testing radiation and a circuit determines from this level whether the obscuration of the second window is excessive. This is used to assess whether the obscuration of the first window is above or below a predetermined level.

Radiation sensing arrangements

A fire and explosion detection and suppression system protects a hangar within which may be stored jet aircraft whose engines may be run up particularly in the re-heat mode. Two radiation sensors are mounted within the hangar and detect for at least predetermined amounts of radiation of predetermined and different types (e.g. one sensor may be a UV sensor and the other may be an IR sensor). When they simultaneously detect sufficient radiation, they operate an AND gate. This fires off suppressor units. To prevent false alarms due to radiation emitted by a running jet engine or a jet engine running in re-heat mode, such a running jet engine is sensed by a transducer responsive to the emitted acoustic or vibrational energy. This blocks the AND gate.

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Windsor, United Kingdom

Nicholas S Allen