PERSPECTIVES OF CONSTRUCTION OF SMOKE-SENSITIVE DETECTORS

The article analyzes the existing designs of smoke-sensitive detectors. This analysis revealed that the important cause of their malfunction is the design of detector body itself due to the lack of free passage of smoke to the sensitive zone. We give an example of the most typical body design of smoke-sensitive detectors, which has rather high-up smoke inlet holes relative to ceiling. In such case, for penetration of smoke particles to the smoke chamber, warm air should go down, or the volume of smoke under the ceiling should increase. This affects the actuation time of sensors. On the basis of this analysis, the authors of the article offer more effective design of the detector. The smoke inlet holes in its body are closer to the ceiling directly on the way of the smoke particles; it increases the probability of penetration of smoke to the smoke chamber. The main characteristic of design of this detector is that the smoke chamber is located above the microchip, contacts and diodes. At the bottom of the detector cover some holes are provided in order to receive vertical upward flow of smoke. Microchip and electrical terminal also have holes for free passage of smoke to the smoke chamber. The authors carried out the comparative theoretical calculation of the actuation time of the most commonly used and new models of detectors in order to evaluate the advantages of the detector design offered by the authors of the article. The results of calculation show that the offered detector design allows ensuring the most rapid penetration of smoke to the smoke chamber and the actuation time of fire alarm shortens.