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Artificial Events: Fire Risk
Published in Maurizio Cumo, Antonio Naviglio, Safety Design Criteria for Industrial Plants, 2019
The optical detectors cannot always replace the ionization detectors.34 The latter have a good sensibility for the whole spectrum of smoke that can be produced by different combustibles; while the scattering smoke detectors have good sensibility only for light smokes, they are not very sensitive to dark smoke, and they are not sensitive to invisible smoke. Therefore, the kinds of combustible material existing in the building and the characteristics of the smoke produced by their ignition are essential to the choice of fire detectors. Everywhere that the smoke detectors cannot be used because the fire does not produce visible or invisible smoke, or because the smoke is normally present in the room, it is necessary to use detectors sensitive to other phenomena which occur with the fire, as the heat detector or flame detector.35
Pre-ignition detection and early fire detection in mining vehicles
Published in Mining Technology, 2021
Point heat detectors can be either a fixed temperature type or a rate-of-rise type, where the rate-of-rise heat detector is activated when the temperature increase per unit time exceeds a certain threshold. Due to its nature, the rate-of-rise heat detector may not activate during a slowly developing fire. The activation of a point heat detector during a fire in a compartment with a distinct ventilation flow may be delayed as the hot fire gases may be diluted and cooled down before reaching the detector. Thus, the positioning of point heat detectors with respect to the fire and ventilation flow is crucial. Point heat detectors have the advantage of being insensitive to environmental conditions typically found in the mining industry.