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。

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

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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。

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

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结果表明，在分析可燃气体泄漏的危险性时，不仅应分析环境空间可燃气体的爆炸浓度范围，而且也要注意存在局部着火的可能性。

The results indicate that when flammable gas risk is analyzed, both the flammable gas explosion scopes in the environment space and local fire possibility should be paid attention to.

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