前郭機械密封包括壓力控制、溫度控制、流體替換(堵塞)和雜質去除系統。在前郭機械密封系(xi)統(tong)(tong)(tong)中(zhong)，上述系(xi)統(tong)(tong)(tong)并不同(tong)時包(bao)括在(zai)內。密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)系(xi)統(tong)(tong)(tong)的(de)(de)選(xuan)擇(ze)主(zhu)要取決(jue)于(yu)主(zhu)密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)件(jian)的(de)(de)應(ying)用(yong)(yong)(yong)范圍。例如，如果(guo)主(zhu)密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)用(yong)(yong)(yong)于(yu)高(gao)溫液體(ti)(ti)(ti)，密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)系(xi)統(tong)(tong)(tong)應(ying)確(que)保(bao)降低主(zhu)密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)的(de)(de)環境(jing)溫度(du)，即采用(yong)(yong)(yong)溫度(du)控(kong)制(zhi)系(xi)統(tong)(tong)(tong)。如果(guo)主(zhu)密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)用(yong)(yong)(yong)于(yu)固體(ti)(ti)(ti)雜(za)質(zhi)含量高(gao)的(de)(de)工作(zuo)介質(zhi)，密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)系(xi)統(tong)(tong)(tong)應(ying)確(que)保(bao)在(zai)主(zhu)密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)前降低固體(ti)(ti)(ti)雜(za)質(zhi)含量，即采用(yong)(yong)(yong)除(chu)雜(za)系(xi)統(tong)(tong)(tong)。在(zai)腐蝕性介質(zhi)中(zhong)，密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)系(xi)統(tong)(tong)(tong)必(bi)須(xu)確(que)保(bao)主(zhu)密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)降低腐蝕速率(lv)或消除(chu)腐蝕，即使用(yong)(yong)(yong)流(liu)(liu)體(ti)(ti)(ti)而不是堵塞流(liu)(liu)體(ti)(ti)(ti)系(xi)統(tong)(tong)(tong)；在(zai)高(gao)壓密(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)裝置中(zhong)，輔助系(xi)統(tong)(tong)(tong)應(ying)確(que)保(bao)多級降壓和其他措(cuo)施，即壓力控(kong)制(zhi)系(xi)統(tong)(tong)(tong)。

　　前郭機械密封的(de)三個(ge)主要功能如(ru)下：

　　1、沖洗功能，沖洗是前郭機械密封基本的功能，它直接將液體注入單面密封或雙面密封的高壓側。一般的前郭機械密封應該沖洗(xi)，特別是(shi)對于(yu)輕(qing)烴泵(beng)，沖洗(xi)時達到隔離介(jie)質(zhi)、冷卻和改善(shan)潤滑的(de)目的(de)。隔離介(jie)質(zhi)的(de)目的(de)可以(yi)通(tong)過(guo)將與(yu)介(jie)質(zhi)相容的(de)液(ye)體引入密(mi)封腔進行(xing)外部循環沖洗(xi)來實現。

　　2、除雜和過濾功能，密封流體中的微細固體粒子、污垢等雜質對前郭機械密封造成的危害非常嚴(yan)重，可(ke)能導致密(mi)封(feng)端面的磨損，也可(ke)能堵塞(sai)寒(han)冷(leng)密(mi)封(feng)系統的管線。密(mi)封(feng)性系統軟件具有(you)去(qu)(qu)除殘(can)渣、保持液(ye)體(ti)清潔(jie)的作用(yong)。當(dang)殘(can)渣的相對(dui)(dui)密(mi)度小于液(ye)體(ti)媒(mei)質相對(dui)(dui)密(mi)度時，能用(yong)過濾(lv)(lv)裝置去(qu)(qu)除殘(can)渣；而(er)當(dang)殘(can)渣的相對(dui)(dui)密(mi)度超過液(ye)體(ti)媒(mei)質相對(dui)(dui)密(mi)度時，可(ke)選用(yong)旋(xuan)液(ye)分離設(she)備(bei)或(huo)網式過濾(lv)(lv)器去(qu)(qu)除殘(can)渣。

　　3、流體替代功能，含有固體顆粒的氣相介質和液相介質的直接密封難度很大，它們溫、毒、貴、易蒸發、易結晶。借助前郭機械密封可以用雙端前郭機械密封代替密(mi)封介質，將難以直接(jie)密(mi)封的介質轉(zhuan)化為(wei)密(mi)封潤滑(hua)性能好、清潔的密(mi)封液(ye)體介質。