三通(tong)(tong)閥門(men)與二通(tong)(tong)閥門(men)外(wai)觀上最明(ming)顯(xian)的差(cha)別(bie)，就是多一個流(liu)道口(kou)。三通(tong)(tong)閥門(men)主要用(yong)于(yu)改變介質流(liu)向，三通(tong)(tong)閥門(men)它除(chu)了進口(kou)A、出(chu)口(kou)B、還有換向口(kou)C，普通(tong)(tong)閥門(men)是不(bu)具備改變介質流(liu)向功能(neng)。

三通閥(fa)(fa)門(men)(men)(men)(men)(men)其工(gong)作(zuo)過程(cheng) ：閥(fa)(fa)門(men)(men)(men)(men)(men)打開介質(zhi)(zhi)(zhi)從A進入閥(fa)(fa)門(men)(men)(men)(men)(men)，經B流(liu)出(chu)(chu)閥(fa)(fa)門(men)(men)(men)(men)(men)，當旁路需(xu)要介質(zhi)(zhi)(zhi)流(liu)入時(shi)，開啟(qi)(qi)執(zhi)行機構，閥(fa)(fa)芯換向，介質(zhi)(zhi)(zhi)A進C出(chu)(chu)，當管線不需(xu)要介質(zhi)(zhi)(zhi)流(liu)入時(shi)，開啟(qi)(qi)執(zhi)行機構°，閥(fa)(fa)門(men)(men)(men)(men)(men)關閉(bi)截斷介質(zhi)(zhi)(zhi)。