In view of status of serious exterior ventilation leakage of auxiliary inclined air returning shaft used for staff and material transportation in Fengchishan Coal Mine. wind meter direct measuring method was used to test mine exterior ventilation leakage of selected test points. winch rope access window of explosion-proof ventilation door was determined as main ventilation leakage sou... https://www.parisnaturalfoodes.shop/product-category/cinnamon-cassia/