Smoldering combustion of flexible polyurethane foam is known to pose a great concern in the context of fire safety. Experiments have been conducted to study the smolder behavior of flexible polyurethane foam at different intensities of heat source in a forced airflow. Smolder behaviors described as smolder velocity, peak temperature and smolder time give distinct signature of temperature history profiles at different input heat fluxes. Correlation between these parameters and the input heat flux that have not been emphasized in the literature is presented. Experimental results showed that the smolder velocities were higher accompanied with shorter smolder time at low input heat flux. In addition, it was observed that the smolder temperature was higher at high input heat flux, which migh...[ Read more ]

Smoldering combustion of flexible polyurethane foam is known to pose a great concern in the context of fire safety. Experiments have been conducted to study the smolder behavior of flexible polyurethane foam at different intensities of heat source in a forced airflow. Smolder behaviors described as smolder velocity, peak temperature and smolder time give distinct signature of temperature history profiles at different input heat fluxes. Correlation between these parameters and the input heat flux that have not been emphasized in the literature is presented. Experimental results showed that the smolder velocities were higher accompanied with shorter smolder time at low input heat flux. In addition, it was observed that the smolder temperature was higher at high input heat flux, which might be strongly associated with the presence of second char oxidation. The second char oxidation found during the smoldering process of polyurethane foam was possibly associated with the high input heat flux accompanied with long smolder period. Effect of the foam length on the smolder behavior was also explored. Smolder velocities were similar for different foam lengths at the same input heat flux. However, the smolder temperature attained was higher for longer length of foam. The high possibility of energy feedback in long foam length was found to relate to the possibility of transition from smoldering to flaming combustion. Through simultaneous thermal analysis, the present experimental observations have provided supplementary understanding of the controlling mechanism on the behavior of forward smoldering of polyurethane foam on the basis of the influence of input heat flux.

In addition to the thermo aspect of smoldering combustion at different input heat flux, smoke emission information was also obtained for complete characterization. The amount of smoke produced and the mass size distribution of particles from smoldering combustion and flaming combustion were obtained and compared. Smoke produced from flaming combustion was found to be significantly higher than smoldering combustion. In addition, the mass median diameters were found to range from 2.18 to 2.59μm for smolder particles, while the yields of CO were ranged form 0.24 to 0.29g/g. Information on the smoke emission data might be useful for the design of an idealized light scattering type smoke detector for smoldering fire.