Fire alarm box with direct and scattered light detection and gas-sensitive layers

摘要

A fire detector for detecting gaseous and dust-like combustion products, having at least one optical transmitter and at least two optical receivers for in each case outputting an electrical signal to a downstream evaluation unit. At least one of the optical receivers is disposed outside of a direct radiation range of the optical transmitter and acts as a scattered-light receiver, and a gas-sensitive layer is interposed in advance of at least one further optical receiver disposed in a direct radiation range of the optical transmitter this layer preferably absorbing light components of a specific narrow wavelength range in response to a contact with a specific gas.