日本SMC減壓閥是通過調節，將進口壓力減至某一需要的出口壓力，并依靠介質本身的能量，使出口壓力自動保持穩定的閥門。從流體力學的觀點看，減壓閥是一個局部阻力可以變化的節流元件，即通過改變節流面積，使流速及流體的動能改變，造成不同的壓力損失，從而達到減壓的目的。
日本SMC減壓閥是采用控制閥體內的啟閉件的開度來調節介質的流量，將介質的壓力降低，同時借助閥后壓力的作用調節啟閉件的開度，使閥后壓力保持在一定范圍內，并在閥體內或閥后噴入冷卻水，將介質的溫度降低，這種閥門稱為減壓減溫閥。減壓閥快易優自動化選型有收錄。該閥的特點，是在進口壓力不斷變化的情況下，保持出口聽壓力和溫度值在一定的范圍內。
日本SMC減(jian)(jian)壓(ya)閥(fa)(fa)按(an)結構形式(shi)(shi)(shi)(shi)(shi)可(ke)分為(wei)薄膜(mo)式(shi)(shi)(shi)(shi)(shi)、彈(dan)簧薄膜(mo)式(shi)(shi)(shi)(shi)(shi)、活塞式(shi)(shi)(shi)(shi)(shi)、杠桿式(shi)(shi)(shi)(shi)(shi)和波(bo)(bo)紋管式(shi)(shi)(shi)(shi)(shi)；按(an)閥(fa)(fa)座(zuo)數目(mu)可(ke)人為(wei)單座(zuo)式(shi)(shi)(shi)(shi)(shi)和雙座(zuo)式(shi)(shi)(shi)(shi)(shi)；按(an)閥(fa)(fa)瓣的(de)(de)(de)位(wei)置不(bu)同可(ke)分為(wei)正作用式(shi)(shi)(shi)(shi)(shi)和反作用式(shi)(shi)(shi)(shi)(shi)。先(xian)(xian)導式(shi)(shi)(shi)(shi)(shi)減(jian)(jian)壓(ya)閥(fa)(fa)當(dang)減(jian)(jian)壓(ya)閥(fa)(fa)的(de)(de)(de)輸(shu)出(chu)壓(ya)力較(jiao)高(gao)或通(tong)徑較(jiao)大時，用調(diao)壓(ya)彈(dan)簧直接調(diao)壓(ya)，則彈(dan)簧剛度必然(ran)過大，流量變化時，輸(shu)出(chu)壓(ya)力波(bo)(bo)動(dong)較(jiao)大，閥(fa)(fa)的(de)(de)(de)結構尺寸也將增大。為(wei)了克(ke)服這些缺(que)點(dian)，可(ke)采用先(xian)(xian)導式(shi)(shi)(shi)(shi)(shi)減(jian)(jian)壓(ya)閥(fa)(fa)。先(xian)(xian)導式(shi)(shi)(shi)(shi)(shi)減(jian)(jian)壓(ya)閥(fa)(fa)的(de)(de)(de)工作原理與直動(dong)式(shi)(shi)(shi)(shi)(shi)的(de)(de)(de)基本相同。先(xian)(xian)導式(shi)(shi)(shi)(shi)(shi)減(jian)(jian)壓(ya)閥(fa)(fa)所用的(de)(de)(de)調(diao)壓(ya)氣體，是(shi)由(you)小型的(de)(de)(de)直動(dong)式(shi)(shi)(shi)(shi)(shi)減(jian)(jian)壓(ya)閥(fa)(fa)供給的(de)(de)(de)。若(ruo)把小型直動(dong)式(shi)(shi)(shi)(shi)(shi)減(jian)(jian)壓(ya)閥(fa)(fa)裝在閥(fa)(fa)體內(nei)部(bu)，則稱(cheng)為(wei)內(nei)部(bu)先(xian)(xian)導式(shi)(shi)(shi)(shi)(shi)減(jian)(jian)壓(ya)閥(fa)(fa)；若(ruo)將小型直動(dong)式(shi)(shi)(shi)(shi)(shi)減(jian)(jian)壓(ya)閥(fa)(fa)裝在主閥(fa)(fa)體外(wai)部(bu)，則稱(cheng)為(wei)外(wai)部(bu)先(xian)(xian)導式(shi)(shi)(shi)(shi)(shi)減(jian)(jian)壓(ya)閥(fa)(fa)。