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1·The conflicting problem of flash point and lower explosive limit as a criterion of hazard is studied in this paper.

文章就闪点与爆炸下限作为危险性判据相抵触的问题进行了探讨。

2·You must use a respirator if the fuel-gas concentration in the work area is 5% more than the lower explosive limit (LEL).

如果工作区域的油气浓度比最低爆炸浓度高出5%，必须使用呼吸器。

3·According to the range of lower explosive concentration limit, methods for how to set up warning region were research.

通过分析氨气扩散后爆炸浓度下限范围，探讨了如何设置警戒区的方法。