Home / Standards / MT 221-1991 MT 221-1991 Abolished 煤矿用防爆灯具 Standard Type MT22 ICS N/A CCS N/A Status Abolished Issue Date 1991-01-15 Implementation 1991-03-01 Centralized Committee 国家矿山安全监察局 Issuing Authority 国家矿山安全监察局