三通(tong)(tong)(tong)(tong)閥(fa)(fa)(fa)門(men)與二通(tong)(tong)(tong)(tong)閥(fa)(fa)(fa)門(men)外觀上最明顯的差(cha)別，就是多一個流(liu)道(dao)口。三通(tong)(tong)(tong)(tong)閥(fa)(fa)(fa)門(men)主要用于改變(bian)介質(zhi)流(liu)向(xiang)，三通(tong)(tong)(tong)(tong)閥(fa)(fa)(fa)門(men)它除了進口A、出(chu)口B、還有換向(xiang)口C，普通(tong)(tong)(tong)(tong)閥(fa)(fa)(fa)門(men)是不具(ju)備(bei)改變(bian)介質(zhi)流(liu)向(xiang)功能。

三(san)通閥(fa)(fa)(fa)門其工作過程(cheng) ：閥(fa)(fa)(fa)門打(da)開(kai)介質(zhi)從(cong)A進入(ru)閥(fa)(fa)(fa)門，經B流(liu)出(chu)閥(fa)(fa)(fa)門，當旁路(lu)需(xu)要介質(zhi)流(liu)入(ru)時(shi)，開(kai)啟(qi)執行(xing)機(ji)構，閥(fa)(fa)(fa)芯(xin)換向，介質(zhi)A進C出(chu)，當管(guan)線不需(xu)要介質(zhi)流(liu)入(ru)時(shi)，開(kai)啟(qi)執行(xing)機(ji)構°，閥(fa)(fa)(fa)門關閉截斷介質(zhi)。