... is use widely use in fire-fighting,chemical industry,shipping,laboratory,mine,petroleum,warehose,factory and metallurgy The RHZK series self ... -cbntained open circuit compressed air bresthing apparatus are used widely for fire-fighting,chemical industry,shipping,laboratory,mine,petroleum,warehose ... 4-6 ≤10 755*460*290. RHZK5/30 Self-contained open-circuit compressed air breathing apparatus