Abstract In the past 5 years the Safety Engineering Group of BASF has determined the static equivalent pressures (“pstat”) of the eight detonative pressure scenarios which explosive gas mixtures can exhibit in long and in short pipes. More precisely, for different combustibles the pstat-values of the corresponding ternary mixtures combustible/O2/N2 were determined on the stoichiometric line and on the O2-line of the explosion triangle. By doing so, the pstat-values of all other compositions inside the explosion triangle could be predicted by extrapolation with an accuracy sufficient for practical applications. Furthermore, a proposal of how to transfer these results to the huge number of other combustibles not investigated so far was provided. A key-parameter in this context was the ratio R between the static equivalent pressure at the point where the deflagration-to-detonation transition occurs in the long pipe and the static equivalent pressure in the region of the stable detonation. In the present work the pstat-values of the new ternary mixture cyclohexane/O2/N2 are reported. Cyclohexane is of special interest because its autoignition temperature (AIT) in air is substantially lower than the AIT-values of all combustibles that have been tested before. According to our hitherto understanding the low AIT should noticeably reduce the ratio R. The experiments, however, did not confirm this hypothesis. After presenting the experimental results, which actually confirm the findings for the combustibles investigated so far, an explanation for the unexpected behaviour regarding R will be presented in terms of the differences between the low-temperature and the high temperature oxidation mechanism. As kind of spin-off, this explanation also allows to better understand quantitatively the degree of precompression in the yet unreacted mixture required for the occurrence of the deflagration-to-detonation Transition (DDT).

中文翻译：

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长管和短管中环己烷/O2/N2混合物爆爆静当量压力的实验测定

摘要 在过去 5 年中，巴斯夫安全工程组确定了爆炸性气体混合物在长管和短管中可能出现的八种爆压情景的静态等效压力（“pstat”）。更准确地说，对于不同的可燃物，相应的三元混合物可燃物/O2/N2 的 pstat 值是在化学计量线上和爆炸三角形的 O2 线上确定的。通过这样做，爆炸三角形内所有其他成分的 pstat 值可以通过外推来预测，其精度足以满足实际应用的需求。此外，还提供了如何将这些结果转移到迄今为止尚未调查的大量其他可燃物的建议。在这方面的一个关键参数是长管中发生爆燃到爆轰转变点的静态当量压力与稳定爆轰区域中的静态当量压力之间的比率 R。在目前的工作中，报告了新的三元混合物环己烷/O2/N2 的 pstat 值。环己烷特别受关注，因为它在空气中的自燃温度 (AIT) 大大低于之前测试过的所有可燃物的 AIT 值。根据我们迄今为止的理解，低 AIT 应显着降低比率 R。然而，实验并未证实这一假设。在展示了实验结果后，实际上证实了迄今为止调查的可燃物的发现，将根据低温和高温氧化机制之间的差异来解释关于 R 的意外行为。作为一种衍生产品，这种解释还可以更好地定量理解发生爆燃到爆轰转变 (DDT) 所需的尚未反应混合物中的预压缩程度。