Abstract
Aspirating smoke detector uses aspirating fan to draw air from the protected area via a network of the sampling pipes and holes, analyses the air and generates warning signals when the concentration of the smoke in the air is over the limit. After the analysis from the view of hydrodynamics, the physical and mathematical models are established. By programming and calculating, the sampling holes' flow rate and the transport time in which the air is drawn from the sampling holes to the detector are got. If each sampling hole's flow rate is not balanceable or the longest calculated transport time exceed 120 seconds (according to NFPA 72), the diameters of the sampling holes are optimized. The calculated results are compared with the experiments, the errors are less than 10%. It is proved that the physical and mathematical models can be used practically.
