為了防(fang)止無(wu)(wu)塵(chen)室(shi)(shi)受(shou)到污染，室(shi)(shi)內必(bi)須保(bao)持正壓(ya)(ya)，如果無(wu)(wu)塵(chen)室(shi)(shi)內壓(ya)(ya)力過高(gao)，造成門扇(shan)不易開關，因而使(shi)用液壓(ya)(ya)閥門來保(bao)持無(wu)(wu)塵(chen)室(shi)(shi)內之(zhi)(zhi)微(wei)正壓(ya)(ya)，通過泄壓(ya)(ya)風門的風量一般在(zai)(zai)100-120m3/h之(zhi)(zhi)間，保(bao)持壓(ya)(ya)差在(zai)(zai)5-40Pa之(zhi)(zhi)間。