Measurements of the characteristic lengths of smoke detectors

The dynamic performance of point-type smoke detectors is described by a simple model including two independent parameters, the static response threshold, and the characteristic length of the detector. An experimental system with constant rate of increase of smoke density under varying velocity conditions is used to determine the model parameters.Nomenclature k constant smoke density gradient (dB/m/s) - L characteristic length of the detector (m) - m_i smoke density inside the detector (dB/m) - m_o smoke density outside the detector (dB/m) - m_or measured smoke density at response (dB/m) - m_r response threshold of the detector (dB/m) - t time(s) - v gas flow velocity at the detector (m/s) - time constant(s)