求翻译：设备、管路在置换合格后，应把所有人孔、手孔、阀门、盲板都打开，并打开室内门窗，加强空气流通。动火区域内的含氢量必须≤0.4%。是什么意思？

After qualifying equipment, pipe replacement, hand holes, blind holes, valves, all plates are open, and open interior doors and Windows, enhanced ventilation. Hydrogen content of fire work in the region must be less than 0.4%.

正在翻译，请等待...

Equipment, pipeline after replacement qualified, should all person hole, the hand hole, the valve, the blind board all open, and opens in the room the windows and doors, the enhancement air circulation.Gets angry in the region to contain the hydrogen quantity to have ≤0.4%.

After qualifying equipment, pipe replacement, hand holes, blind holes, valves, all plates are open, and open interior doors and Windows, enhanced ventilation. Hydrogen content of fire work in the region must be less than 0.4%.

After qualifying equipment, pipe replacement, hand holes, blind holes, valves, all plates are open, and open interior doors and Windows, enhanced ventilation. Hydrogen content of fire work in the region must be less than 0.4%.