乃東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。在乃東機械密封系(xi)(xi)統(tong)(tong)(tong)中(zhong)(zhong)，上述(shu)系(xi)(xi)統(tong)(tong)(tong)并不同時包括在(zai)(zai)內。密(mi)(mi)(mi)(mi)封(feng)(feng)系(xi)(xi)統(tong)(tong)(tong)的選(xuan)擇主(zhu)要取決于主(zhu)密(mi)(mi)(mi)(mi)封(feng)(feng)件的應用(yong)(yong)范(fan)圍。例(li)如，如果主(zhu)密(mi)(mi)(mi)(mi)封(feng)(feng)用(yong)(yong)于高溫(wen)液體(ti)，密(mi)(mi)(mi)(mi)封(feng)(feng)系(xi)(xi)統(tong)(tong)(tong)應確保(bao)降(jiang)低(di)主(zhu)密(mi)(mi)(mi)(mi)封(feng)(feng)的環(huan)境溫(wen)度(du)(du)，即采(cai)用(yong)(yong)溫(wen)度(du)(du)控(kong)制系(xi)(xi)統(tong)(tong)(tong)。如果主(zhu)密(mi)(mi)(mi)(mi)封(feng)(feng)用(yong)(yong)于固(gu)體(ti)雜(za)質(zhi)含量高的工作(zuo)介質(zhi)，密(mi)(mi)(mi)(mi)封(feng)(feng)系(xi)(xi)統(tong)(tong)(tong)應確保(bao)在(zai)(zai)主(zhu)密(mi)(mi)(mi)(mi)封(feng)(feng)前降(jiang)低(di)固(gu)體(ti)雜(za)質(zhi)含量，即采(cai)用(yong)(yong)除(chu)雜(za)系(xi)(xi)統(tong)(tong)(tong)。在(zai)(zai)腐蝕(shi)(shi)性介質(zhi)中(zhong)(zhong)，密(mi)(mi)(mi)(mi)封(feng)(feng)系(xi)(xi)統(tong)(tong)(tong)必須確保(bao)主(zhu)密(mi)(mi)(mi)(mi)封(feng)(feng)降(jiang)低(di)腐蝕(shi)(shi)速率或消除(chu)腐蝕(shi)(shi)，即使(shi)用(yong)(yong)流體(ti)而(er)不是堵塞(sai)流體(ti)系(xi)(xi)統(tong)(tong)(tong)；在(zai)(zai)高壓(ya)(ya)密(mi)(mi)(mi)(mi)封(feng)(feng)裝置中(zhong)(zhong)，輔助系(xi)(xi)統(tong)(tong)(tong)應確保(bao)多級(ji)降(jiang)壓(ya)(ya)和其他措(cuo)施，即壓(ya)(ya)力控(kong)制系(xi)(xi)統(tong)(tong)(tong)。

　　乃東機械密封的(de)三個主要功能如下：

　　1、沖洗功能，沖洗是乃東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。一般的乃東機械密封應該沖洗(xi)，特(te)別是對(dui)于(yu)輕烴泵，沖洗(xi)時達(da)到隔(ge)離介質(zhi)(zhi)、冷卻和改善潤滑的目的。隔(ge)離介質(zhi)(zhi)的目的可(ke)以(yi)通過將與介質(zhi)(zhi)相(xiang)容的液體引入密封腔進行外部(bu)循環(huan)沖洗(xi)來(lai)實現(xian)。

　　2、除雜和過濾功能，密封流體中的微細固體粒子、污垢等雜質對乃東機械密封造成的危(wei)害非常嚴重，可能導致密(mi)(mi)(mi)(mi)封端面的磨損，也(ye)可能堵(du)塞寒(han)冷密(mi)(mi)(mi)(mi)封系統(tong)的管(guan)線。密(mi)(mi)(mi)(mi)封性系統(tong)軟件具有去除殘(can)(can)(can)渣、保持液(ye)體(ti)清潔的作用。當殘(can)(can)(can)渣的相(xiang)對(dui)密(mi)(mi)(mi)(mi)度(du)小于液(ye)體(ti)媒質相(xiang)對(dui)密(mi)(mi)(mi)(mi)度(du)時，能用過(guo)(guo)濾裝置(zhi)去除殘(can)(can)(can)渣；而當殘(can)(can)(can)渣的相(xiang)對(dui)密(mi)(mi)(mi)(mi)度(du)超過(guo)(guo)液(ye)體(ti)媒質相(xiang)對(dui)密(mi)(mi)(mi)(mi)度(du)時，可選用旋液(ye)分離設備或(huo)網式過(guo)(guo)濾器去除殘(can)(can)(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。借助乃東機械密封可以用雙端乃東機械密封代替密(mi)(mi)(mi)封介(jie)質，將難以直(zhi)接密(mi)(mi)(mi)封的介(jie)質轉化(hua)為(wei)密(mi)(mi)(mi)封潤(run)滑性能好、清(qing)潔的密(mi)(mi)(mi)封液體介(jie)質。