Cone calorimeter and controlled atmosphere cone calorimeter experiments were conducted on various samples. The intent of the tests was to examine the behavior of uniform and composite samples in a range of thicknesses, irradiances, and oxygen concentrations.Single, uniform layers of acrylonitrile butadiene styrene (ABS) were compared to a composite mix, comprising of ABS with a surface layer of cardboard and a secondary layer of polyethylene bubble wrap (intended to represent a potential storage arrangement). The horizontal samples have been tested at irradiances of 25 and 50 kW/m 2 and oxygen concentrations of 20.95%, 17%, and 15% to examine a range of significant variables. Results for the uniform arrangement indicated various correlations, previously observed in the works of others, such as the relationships typically described between applied heat flux, ignitability, heat release rate and the effect of the introduction of hypoxic conditions. However, results were shown to change significantly when samples were arranged to feature composite layers. A hypothesized cause of the behavioral change, namely the soot and char residual introduced from the incomplete combustion of the cardboard layer, highlights further important variables that require consideration in material testing under hypoxic conditions. Such variables, namely specific material behaviors and sample orientation, must be sufficiently captured in the design methodologies of systems reliant upon the introduction of hypoxic conditions. It is concluded that sufficiently capturing a wider range of variables in burning materials under hypoxic conditions will introduce further design resilience and help optimize fire protection/prevention methods.

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Cone calorimeters are widely used to assess heat release parameters and flammability of combustible materials, but their use is limited for applications where the global equivalence ratio (GER) exceeds one, because they can only replicate burning in open conditions. The standardisation of the controlled atmosphere cone calorimeter (CACC) in the ISO/TS 5660-5:2020 offers an opportunity to investigate the potential advantages and limitations of this apparatus. This paper presents a detailed review of existing studies conducted using the CACC. The review is aimed at examining the importance of atmospheric control for bench-scale experimental methods and the research-based development of key features of the apparatus. In addition, it highlights the research yet to be carried out to optimise the use of CACC as a tool in fire science. The effects of various design parameters are discussed including the method used for GER control, the chimney, the chamber, the gas inflow rate and others. Despite standardisation, it is concluded that there is limited consensus on optimal CACC control variables. A lack of consensus has led to significantly different testing conditions even where researchers use the same materials and have similar research objectives. The lack of best practice, particularly with regards to a gas sampling location and the method of GER control, motivates the need for further research so as to improve the value of data collected, reduce uncertainty and optimise CACC reproducibility.