摘要 |
A fire detection system for monitoring a volume (2) containing fluid, typically air, for the presence of smoke particles is disclosed. A conduit (3) for receiving the fluid, and any smoke particles therein, and directing the fluid to a smoke detector (1) has a plurality of inlets (6A, 6B) formed therein. A respective temperature sensor (17, 19) is associated with each of the inlets (6A, 6B) which generate a signal indicative of a change in temperature in the region of the inlet. In the embodiments, the temperature sensor comprises one or more fibre Bragg gratings. The fibre Bragg gratings preferably have different grating periods. The reflected light from each fibre Bragg grating is returned back down the fibre optic cable (11) and redirected via a 2x1 coupler (51) to a wavelength detection system (53) and a personal computer (63). The combination of wavelength detection system (53) and personal computer (63) allow analysis of the reflected light patterns, as well as providing a user interface which enables detection of the occurrence of a spatial and/or a temperature variation. The location of the said variation along the fibre optic cable (11) is advantageously detectable. The system described is highly sensitive to smoke, but can advantageously also provide an indication of the location of the smoke source, because any variation in temperature at any one of the smoke inlets is also detected, the location of the sensor being known. |