The CoaST-Fire: A novel methodology to rapidly expose materials to various fire curves

A new method for testing materials under simulated fire conditions is introduced. The fundamentally new approach relies on the movement of the sample through zones with a spatially increasing temperature. Adjusting the velocity profile with which the sample is moved makes it possible to expose it to practically any temperature-time curve defined in fire safety standards, from extremely rapid hydrocarbon to more gradual cellulosic fire conditions. This manuscript presents a prototype named CoaST-Fire that capitalises on this concept by combining a vertical tube furnace with a vertical motion system. The methodology to calibrate the furnace temperature profile, as well as to calculate the velocity profiles are discussed. The velocity profiles are then used to replicate a range of temperature-time curves with exceptional accuracy and reproducibility. A numerical model is developed in COMSOL Multiphysics to study heat fluxes towards the steel substrate as a function of time and thermal insulation. Finally, proof-of-concept experiments with two commercial intumescent coatings are presented. The experiments are shown to be highly repeatable while images of the coatings during the experiments can provide additional insights into the occurring reaction steps. Furthermore, CoaST-Fire makes it possible to conduct experiments under various O-2 concentrations and could later be extended with a gas outlet analysis system. The study is in line with recent efforts to develop cheaper and more rapid testing methods for early research and development of intumescent coatings and the setup could potentially also be used to test other types of materials.