Suppression effect of expandable graphite on fire hazard of dust layers

Expandable graphite (EG) has potential to inhibit the fire hazard of dust layers. This suppression effect was systematically studied by comparing with that of traditional inertants such as CaCO3 and NaHCO3. The thermal expansion of EG can generate compact char layers with low thermal conductivity, which effectively inhibited the heat transfer between the heat source and the surrounding dusts. Oxygen diffusion was also hindered between the dust layer and the environment. Therefore, a small amount of EG could achieve a suppression effect for layer fires equivalent to a large amount of traditional inertants. A small amount of traditional inertants promoted the combustion of the non-metal dust layer, a phenomenon that did not occur while using EG. In addition, EG also acted as an effective flame retardant on the flame spread of the non-metallic dust layer under inclined conditions. Most important, EG had a suppression effect on down-flowing moving pool fires of non-metallic dust layers and the violent combustion of metal dust layers. This shows great potential not available in traditional inertants. EG could be considered as a novel and well-integrated dust layer fire inhibitor in process industries handing combustible dusts.

Automated summary

Expandable graphite (EG) has the potential to inhibit the fire hazard of dust layers by generating compact char layers to hinder heat transfer and oxygen diffusion. Compared to traditional inertants, a small amount of EG achieves equivalent suppression effect and also acts as a flame retardant.