電動球閥前后雙重密封結構設計 THE bi-sealing design structure,i seat in front of the ball and seat sealing behind the ball
對于某些特定的工況要求以及用戶要求，固定球閥可以采用球前球后雙重密封結構設計，即是其中一個密封副因意外情況密封失效，閥門仍然能夠正常工作，從而提高了閥門的密封可靠性，
對于球前閥座，有D1，D2的面積差形成的活塞效應，在閥前后的介質壓差作用下，加上彈簧的預緊力使球閥前閥座與球體緊密接觸而密封，并且密封力隨著介質壓差的增大而增加。
對于球后閥座，有D2，D3的面積差形成的活塞效應，在閥座前后的介質壓差作用下，加上彈簧的預緊力使球后閥座與球體緊密接觸而密封，并且密封力隨著介質壓差的增大而曾加。

According to some special working conditions and customers, requirement ,MINGTAI has provided the trunnion ball valve with the BI sealing design structure ,seat sealing in front of the ball and seat sealing behind the ball ,thus the reliable sealing of the valve is ensured because the valve can perform normally even if one of the effective sealing designs becomes lost due to the abnor malcondition