Siemens Schweiz Ag

Harald Ebner

Martin Forster

Hilmar Konrad

Aleksandar Duric

A flame detector, may be aligned to cover a region to be monitored near a body water. The flame detector has at least one radiation sensor and a downstream evaluation unit. The at least one radiation sensor is sensitive to light in the spectrum of open fire. The evaluation unit outputs a fire alarm in the event of fluctuations or flicker frequencies characteristic of open fire being detected. A linear polarizing filter positioned upstream of the radiation sensor(s) has a polarization plane rotated about a main receiving direction to largely suppress the horizontal component of the received light, based on the knowledge that light reflected from water surfaces is predominantly horizontally polarized. If characteristic flicker frequencies and a significant degree of polarization are simultaneously detected in the received light, the detector identifies sunlight reflected off bodies of water and modulated by the swell, and a false alarm output is inhibited.

Flame detector for monitoring a region adjacent to bodies of water and taking into consideration a degree of polarization present in the received light for the activation of a fire alarm

A method and test devices are used for field calibration of gas detectors. Brand new gas detectors are used as measurement standards in field calibration. The brand new gas detectors are in this case either employed directly as working standards, in which case the regular calibration by a reference standard is dispensed with, since the brand new gas detectors are always deemed to be sufficiently accurate. Alternatively, the brand new gas detectors are employed directly, namely as sufficiently accurately calibrated reference standards for the reference gas sensors acting as working standards and incorporated into the test device. In both cases the measured values of the gas sensors in the gas detectors to be calibrated are fed back to a sufficiently calibrated system, namely either directly to at least one brand new gas detector as a working standard or else to a reference sensor of a calibrated test device.

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Baar, Switzerland

Harald Ebner