The principle of increasing gas emission rate by long hole blasting in the crossing hole is discussed. The radius cracked zone in coal seam caused by long hole blasting is calculated.
简要论述了深孔爆破提高瓦斯抽放的机理，以煤体中柱状装药爆炸后的裂隙圈半径进行了计算。
The measures to control the vapor purging time and flow rate of vapour, enlarge the oil-gas space and increase the number of air hole as well as venting area are given, which can effective...
提出采取严格控制扫线作业时间和扫线蒸汽流量，增大油气空间的体积和增加罐顶通气孔数量和面积等措施，可有效地预防该类事故的发生。
The defects of sand-slag and gas-hole are absent in the water-cooling-sprayer whose surface is clean and qualified rate is more than 90%.
结果表明：铸件表面光洁，无砂眼、气孔等缺陷，铸件合格率高于90%；
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