GOST R 52139-2003 可燃气体检测与测量用电气设备.第4部分:显示体积分数达100%爆炸下限的Ⅰ1组设备的性能要求
Electrical apparatus for the detection and measurement of flammable gases. Part 4. Performance requirements for group I1 apparatus indicating a volume fraction up to 100 % lower explosive limit