The wind duct has an air leakage rate per hundred meter of only 3.67%, and when used for forced ventilation, it has remarkable advantages and is worth popularization. But it cannot be used as wind extraction duct under the intensified ventilation conditions. 风筒的百米漏风率只有3.67%,这种风筒作为压入式风筒使用时,具有很明显的优点,值得推广,但是在强化通风的条件下,不能作为抽出式风筒使用。