... can reduce the 80%dust,improve working environment. I use: coal injection ,dust-fall,coal preesure reduction,coal-crack,methane drainage, ... 4. high pressure water injection ,breaking coal mass ,reducing cost, and enhancing the workers feeling of safety;5. use the hole sealing device ... no peron in front of the working device.VI. Carried Standard :GB/T 10544-2003 Water Injection and Hole-Sealing Device ...