Cone calorimeter and controlled atmosphere cone calorimeter experiments were conducted on various samples. The intent of the tests was to examine the behaviour 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 kW/m2 and 50 kW/m2 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 hypothesised cause of the behavioural 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 behaviours 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 optimise fire protection/prevention methods.
The authors would like to thank the material suppliers, lab staff, and associated organizations that supported the work over a challenging period interrupted by the onset of the Covid-19 pandemic as it spreads into Europe. Robert John Bray would also like to thank the International Masters in Fire Safety Engineering (IMFSE) program for the support and guidance that assisted with the completion of the project.
© 2021 The Authors. Fire and Materials published by John Wiley & Sons Ltd.
- cone calorimetry
- Bubble wrap
- Metals and Alloys
- Ceramics and Composites
- General Chemistry
- Electronic, Optical and Magnetic Materials
- Polymers and Plastics
- bubble wrap