Patent ID: 8890700
Filing Date: 2014-11-18
Classification: G01N,G08B

Abstract:
1. A method for hazard detection using a scattered-light principle, comprising: irradiating particles to be detected with first light in a first wavelength range and second light in a second wavelength range; scattering the first and second lights by the particles to produce first and second scattered-light signals respectively from the first and second lights; normalizing the first and second scattered-light signals with respect to one another to produce first and second normalized scattered-light signals having amplitude profiles approximately corresponding to steam or dust particles; forming an amplitude ratio between the normalized scattered-light signals; defining an amplitude comparison value, which corresponds to a particle dimension in a cross-over area from smoke to dust/steam; comparing the amplitude ratio with the amplitude comparison value, for processing the normalized scattered-light signals for fire characteristic values; if the amplitude ratio exceeds the amplitude comparison value, evaluating the first normalized scattered-light signal and emitting a dust/steam density signal; and if the amplitude ratio is less than or equal to the amplitude comparison value, evaluating the second normalized scattered-light signal and emitting a smoke density signal.