A Simple Fire Performance Model for Intumescent Fire Retardant Coatings

摘要

This paper presents a practical engineering model to determine the flammability properties and predict the fire performance of Intumescent Fire Retardant (IFR) coatings applied on a 5.0 mm inert steel substrate in the Cone Calorimeter. The present model simplifies the complete conservation equations governing the IFR system by utilizing the facts that the IFR coating layer is thermally thin and its expanding char layer has negligible volumetric heat capacity. These simplifications eliminate the requirement in the existing models for determination of numerous expansion and thermal properties for the IFR coating and its resulting char. The thermal insulation effect of the expanded char is represented as a ratio between the heat flux received by the substrate and the heat flux imposed on the substrate surface for the case there is no char layer. This heat flux ratio is expressed as a function of a modified expansion intumescent height, which is related to the mass loss of the IFR coating as determined from modelling of mass loss rate based on TGA measurements. The accuracy and robustness of the model are validated by comparing its predictions of expansion height and steel plate temperature in Cone Calorimeter experiments at different heat fluxes for two commercial IFR coatings having different initial masses.