為(wei)了防(fang)止無塵室(shi)受到(dao)污(wu)染，室(shi)內必須保(bao)持(chi)(chi)正壓，如果無塵室(shi)內壓力過高，造成(cheng)門(men)(men)扇不易開關，因而使用(yong)液壓閥門(men)(men)來保(bao)持(chi)(chi)無塵室(shi)內之(zhi)微正壓，通(tong)過泄壓風(feng)門(men)(men)的風(feng)量一般在(zai)100-120m3/h之(zhi)間(jian)(jian)，保(bao)持(chi)(chi)壓差在(zai)5-40Pa之(zhi)間(jian)(jian)。