Scattered radiation fire detector and method for the automatic detection of a fire situation

摘要

A scattered radiation fire detector having radiation sources of different wavelengths and a scattered radiation sensor, which are arranged and formed so that their optical axes are directed at a common centre of a scattering volume. A sensor unit is furthermore formed to register forward scattering I1(λ1,fwd) of a first radiation source, forward scattering I2(λ2,fwd) of a second radiation source and backward scattering I3(λ1,bwd) of a further first radiation source, to calculate scattered radiation intensity quotients Q1=I1(λ1,fwd)/I2(λ2,fwd), Q2=I1(λ1,fwd)/I3(λ1,bwd) and Q3=I2(λ2,fwd)/I3(λ1,bwd) and to detect the existence of a fire situation using the scattered radiation intensity quotients.

主权项

1. A scattered radiation fire detector comprising:
two first radiation sources of a first wavelength (λ1), a second radiation source of a longer second wavelength (λ2), and a sensor unit having a scattered radiation sensor sensitive to the first and second wavelengths, wherein the first radiation sources, the second radiation source and the scattered radiation sensor are arranged and formed in such a way that the optical axes thereof are directed at a common centre of a scattering volume, wherein forward scattered radiation intensities I1(λ1,fwd) of one of the first radiation sources, forward scattered radiation intensities I2(λ2,fwd) of the second radiation source and backward scattered radiation intensities I3(λ1,bwd) of the other of the first radiation sources are detected by the scattered radiation sensor, and wherein the sensor unit is configured to calculate the scattered radiation intensity quotients Q1=I1(λ1,fwd)/I2(λ2,fwd), Q2=I1(λ1,fwd)/I3(λ1,bwd) and Q3=I2(λ2,fwd)/I3(λ1,bwd), to detect the existence of a fire situation using the scattered radiation intensity quotients.