Siemens Aktiengesellschaft

Cerberus Ag

Siemens Building Technologies Ag

Kurt Hess

Andreas Scheidweiler

Marc P Thuillard

Urs Riedi

Max Schlegel

The fire detector comprises an insertable detector assembly which includes a sensor arrangement, an electronic evaluation system and a housing which surrounds the sensor arrangement and has openings to provide access by air and, when applicable, smoke to the sensor arrangement. The detector is of modular construction and is configured to accommodate detection modules having sensors for different fire parameters, all detection modules being compatible with a single housing. The detection module may be configured for optical, thermal or optical-thermal fire detection and/or for detecting combustion gases. The sensor arrangement and the above-mentioned access openings are arranged substantially in one plane, whereby a shallow construction is achieved even in the case of a multi-criterion detector. The detection modules have a carrier plate which is identical for all detector types and is insertable in the detector, which carrier plate is configured to accommodate the sensors for the different fire parameters.

Fire detector

The smoke detector contains an optical measuring chamber, having a sensor arrangement () with at least one light source (') and one light receiver (), and a labyrinth system () with screens () arranged on the periphery of the measuring chamber. The light source (&#x2032;) and the light receiver () are each arranged in a housing (). The above-mentioned housings () have an elongated shape and a small window opening The at least one light source (&#x2032;) and light receiver (&#x2032;) are arranged in the rear part of their housings (), so that between the window openings of the housings () and the light-penetrated optical surfaces of the at least one light source (&#x2032;) and/or the lens of the light receiver () a relatively large gap is formed. This gap is preferably greater than the diameter of the above-mentioned optical surfaces, or of the above-mentioned lens. In the measuring chamber between the light exit and entry side of the housings () and the screens () opposite them, a compact, open scattering space is formed.

Scattered light smoke detector

In a scattered-light smoke detector, for preventing false alarms due to extraneous matter in a measurement chamber (1), a radiation source (2) and two radiation detectors (7, 8) are included. An evaluation circuit is provided for comparing the two detector signals, and an alarm signal is triggered if at least one of the detector signals exceeds a predetermined threshold, and if the two detector signals are at least approximately equal. In another embodiment, a scattered-light smoke detector includes two radiation sources (2, 22), a radiation detector (7), and circuitry for alternatively activating one (2) or the other (22) radiation source. For comparison, corresponding detector signals are stored in sample-and-hold circuits, and an alarm signal can be triggered depending on the same tests. Furthermore, in both cases, a trouble signal can be produced if the two signals are significantly different.

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Wolfhausen, Switzerland

Kurt Hess