拍門具有流道正向單向開啟和反向關閉的作用。拍門的閥蓋借助于自身配重的平衡作用，在水流的作用下使門頁自動開啟或關閉，或稍加外力作用使門頁開啟或關閉；
The flap door has the function of opening and closing the flow channel in both forward and reverse directions. The valve cover of the door is balanced by its own weight, which automatically opens or closes the door leaf under the action of water flow, or slightly applies external force to open or close the door leaf;
拍門蓋上設有拉環，拉動拉環此蓋的開啟角度應大于60度，無卡阻現象，開關應自由靈活，當拍門部分泡在水中，管道內部壓力較大，反向壓力較小時，拍門允許部分泄漏量，當河道水壓增大時，拍門將自動關閉密封。
The flap door cover is equipped with a pull ring, and the opening angle of the flap should be greater than 60 degrees when pulled. There should be no jamming phenomenon, and the switch should be free and flexible. When the flap door is partially submerged in water and the pressure inside the pipeline is high, and the reverse pressure is low, the flap door allows for partial leakage. When the water pressure in the river increases, the flap door will automatically close and seal.