Xiaomin Ni

Experimental Study of New Gas-Solid Composite Particles in Extinguishing Cooking Oil Fires

New gas—solid composite particles appropriate for extinguishing cooking oil fires will be reported in this article. This powder product is composed of zeolite 13X particles of diameter 1—2 μm and absorbed 2-bromo-3,3,3-trifluoropropene. The preparation and physicochemical properties of the composite particles will be reported. Their performance and possible mechanism in extinguishing cooking oil fires are then investigated with full-scale burning tests. Experiments were carried out in a room of length 3 m, width 3 m, and height 3 m. A cooking oil pool fire of diameter 0.25 m was ignited by ethanol and burnt inside the room. Different dry powder products were also evaluated. Their suppression effect was compared with that of this new product. Results indicated that the new composite particles have better performance in extinguishing cooking oil fires in comparison with other dry powder tested. Relatively shorter extinguishing time was achieved with smaller amount of agents required without any re-ignition. The new composite particles give better performance in suppressing cooking oil fires because of highly efficient free flame radical scavengers, improved cooling capacity, hydrophobic and oleophobic surface. Chemical suppression effects are reported.

Proposed fire screening tests on plastic foams with a cone calorimeter in Hong Kong

Many big building fires happened in the past involved burning furniture foam. In some places such as Hong Kong, foams treated with fire retardant additives are only required to test their ignitability under a small flame. It was proposed earlier that the behaviour of furniture foam in flashover fires should be assessed more extensively by a cone calorimeter under high radiative heat fluxes. In this paper, this screening approach is further studied using five samples, including three different pillow foams, one mattress foam and one expensive fire-safe sofa foam. Both thermal and smoke aspects were studied in a cone calorimeter under heat fluxes of 20 kWm-2, 30 kWm-2, 50 kWm-2 and 70 kWm-2. It was observed that all the foam samples were burnt under heat fluxes above 30 kWm-2. Only one pillow foam sample was not ignited under a low incident heat flux of 20 kWm-2, but it morphed into a mixture of solid and liquid. Under heat fluxes above 30 kWm-2, the fire-safe foam burnt vigorously; the burning showed no differences from foam without fire retardant. The fire-safe foam even released more smoke and toxic gases with higher carbon monoxide concentration. From the above cone calorimeter test, foams commonly used in the market can only withstand small match fires to delay ignition time. Foam products should be protected by additional provisions, such as an external cover, to protect them against big fires.