Spontaneous Combustion of Paint Loaded Filters

(CSE) performed an analysis of the self-initiated thermal decomposition phenomenon of paint-loaded filters that has occurred on several occasions as reported by the Iowa Waste Reduction Center. By conducting a series of self-heating tests on samples of filters loaded with paint, CSE has shown that in selected circumstances the exothermic decomposition of the paint-loaded filters could lead to thermal runaway and eventually ignition of the filters. These circumstances are related to the temperature, size, and composition of materials surrounding the filters. The exothermic decomposition of the paint releases energy. If the energy generated within the pile is greater than the energy lost from the pile, the internal temperature will increase. The non-linear nature of the chemical reactions promotes an exponential rise in the temperature, eventually reaching the ignition temperature of the paint and/or filters. At a certain critical pile size the configuration does not allow effective dissipation of the energy produced by the reaction for a given temperature. CSE's test data were used to determine the Frank-Kamenetskii parameter for self-heating and the results indicate that the packing density is the single most critical factor. Furthermore, filters loaded with paint with a higher VOC content are more prone to self-heat than filters with a lower VOC content. To correct the self-heating problem, the geometry of the storage of the filters must be changed to allow for less temperature build-up and better heat dissipation. This can be effectively accomplished by reducing the volume of the storage containers and by reducing the packing density (number of filters per volume unit). In addition, filters should never be mixed with ordinary trash, as trash surrounding the filters will cause the same insulating effect as tightly packed filters.