Field test of optical and electrical fire detectors in simulated fire scenes in a cable tunnel

Abstract

This paper presents the testing results of three types of fire detectors: electrical heat sensing cable, optical fiber Raman temperature sensing detector, and optical fiber Bragg grating (FBG) temperature sensing detector, in two simulated fire scenes in a cable tunnel. In the small-scale fire with limited thermal radiation and no flame, the fire alarm only comes from the heat sensors which directly contact with the heat source. In the large-scale fire with about 5 ℃/min temperature rising speed within a 3-m span, the fire alarm response time of the fiber Raman sensor and FBG sensors was about 30 seconds. The test results can be further used for formulating regulation for early fire detection in cable tunnels.

Research summary of cable channel fire extinguishing technology

“…Each fire particles have a cap on the critical particle size, less than the critical size of particles all fire extinguishing effect, extinguishing efficiency is greater than the critical size of particles sharply reduced, but the momentum is big, aerodynamic force on the small particles through air, forcing small particles, followed by pouncing on the flame center, rather than before the flame was blown away, a stream of lower extinguishing efficiency. The particle size of common dry powder extinguishing agent is between 10~75 m, which has poor dispersion and relatively small specific surface area [11].…”