许用炸药 meaning in Chinese

permitted explosive

Test method and ajudgment of safety of permissible explosive in inflammable gas
煤矿许用炸药可燃气安全度试验方法及判定
Test method and adjudgement of safty of permissible explosive in grime and inflammable gas
煤矿许用炸药煤尘?可燃气安全度试验方法及判定
Test method and judge rules of safety of permissible explosive for coal mining in firedamp
煤矿许用炸药井下可燃气安全度.试验方法和判定规则