The development of a model for the prediction of polymer spontaneous ignition temperatures in high pressure enriched oxygen across a range of pressures and concentrations

Abstract

High pressure enriched oxygen is used in a wide number of areas, including aircraft, medical breathing apparatus, diving, mining and mountaineering operations. It is also used for a number of industrial processes, but is most commonly used for combustion. Where the pressure or concentration of oxygen is increased well above that of atmospheric, oxidation reactions occur more readily, and at a faster rate, relative to those under atmospheric conditions. Thus the criteria used for polymer selection is key to preventing, or at least limiting, the possibility of a catastrophic oxygen incident which endangers both property and human life. In this work spontaneous ignition temperature (SIT) data obtained in high pressure enriched oxygen from both differential scanning calorimetry and oxygen bomb testing are compared. A model is derived to enable the calculation of a SIT of a non-metal at any pressure and oxygen concentration using existing test data from other pressures. This has been shown to work with reasonable success for most materials tested, being validated using the comparison of test data from the oxygen bomb test and Pressurised Differential Scanning Calorimetry (PDSC) testing. These results may indicate the suitability of a PDSC for safety testing in the future. Further work is needed to increase the data base of ignition test data from PDSCs, and thermodynamic constants to allow for the direct comparison, and to assess the suitability of this apparatus for safety testing of more materials. AcknowledgmentsFunding: This work was supported by the UK Ministry of Defence and Harrier Jaguar Survival IPT. This funding source had no role in the study design; in the collection, analysis and interpretation of data; in the writing of the report; or in the decision to submit the article for publication.

Identification of ignition sources in high pressure enriched gaseous oxygen system incidents using flow chart road map diagram methodology

“…The inner lining of the hose was made of PTFE (external diameter, 8.42-8.51 mm, thickness, 0.957-0.999 mm). At the system pressure of 20.7 MPa the SIT of PTFE has been calculated to be approximately 760 K (Benson et al 2016). The stainless steel and brass materials have melting points (which can be used as probable SIT values re.…”