洞頭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。在洞頭機械密封系(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)中(zhong)，上述系(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)并不(bu)同時包括在內(nei)。密(mi)(mi)(mi)封(feng)(feng)(feng)系(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)的選(xuan)擇主(zhu)(zhu)(zhu)要取決(jue)于主(zhu)(zhu)(zhu)密(mi)(mi)(mi)封(feng)(feng)(feng)件的應(ying)(ying)用(yong)(yong)范(fan)圍。例如，如果主(zhu)(zhu)(zhu)密(mi)(mi)(mi)封(feng)(feng)(feng)用(yong)(yong)于高(gao)溫(wen)液體(ti)，密(mi)(mi)(mi)封(feng)(feng)(feng)系(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)應(ying)(ying)確(que)(que)保(bao)降低(di)(di)主(zhu)(zhu)(zhu)密(mi)(mi)(mi)封(feng)(feng)(feng)的環(huan)境溫(wen)度，即采用(yong)(yong)溫(wen)度控制(zhi)系(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)。如果主(zhu)(zhu)(zhu)密(mi)(mi)(mi)封(feng)(feng)(feng)用(yong)(yong)于固體(ti)雜(za)(za)質(zhi)含(han)(han)量高(gao)的工作(zuo)介(jie)質(zhi)，密(mi)(mi)(mi)封(feng)(feng)(feng)系(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)應(ying)(ying)確(que)(que)保(bao)在主(zhu)(zhu)(zhu)密(mi)(mi)(mi)封(feng)(feng)(feng)前降低(di)(di)固體(ti)雜(za)(za)質(zhi)含(han)(han)量，即采用(yong)(yong)除(chu)雜(za)(za)系(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)。在腐(fu)(fu)蝕性(xing)介(jie)質(zhi)中(zhong)，密(mi)(mi)(mi)封(feng)(feng)(feng)系(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)必須確(que)(que)保(bao)主(zhu)(zhu)(zhu)密(mi)(mi)(mi)封(feng)(feng)(feng)降低(di)(di)腐(fu)(fu)蝕速(su)率或消除(chu)腐(fu)(fu)蝕，即使(shi)用(yong)(yong)流(liu)體(ti)而不(bu)是(shi)堵塞流(liu)體(ti)系(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)；在高(gao)壓(ya)密(mi)(mi)(mi)封(feng)(feng)(feng)裝置中(zhong)，輔(fu)助系(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)應(ying)(ying)確(que)(que)保(bao)多級降壓(ya)和其(qi)他措(cuo)施，即壓(ya)力(li)控制(zhi)系(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)。

　　洞頭機械密封的三(san)個主要功能如(ru)下(xia)：

　　1、沖洗功能，沖洗是洞頭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。一般的洞頭機械密封應該(gai)沖洗，特別是對于輕烴泵，沖洗時達到隔離介(jie)質(zhi)、冷(leng)卻和改善潤滑的(de)(de)目的(de)(de)。隔離介(jie)質(zhi)的(de)(de)目的(de)(de)可(ke)以通過將(jiang)與介(jie)質(zhi)相容的(de)(de)液體(ti)引入密(mi)封腔進行外部循環沖洗來實現。

　　2、除雜和過濾功能，密封流體中的微細固體粒子、污垢等雜質對洞頭機械密封造成的危害非(fei)常(chang)嚴(yan)重，可能導致密(mi)(mi)(mi)封端(duan)面(mian)的磨損，也(ye)可能堵塞(sai)寒冷密(mi)(mi)(mi)封系統的管線。密(mi)(mi)(mi)封性(xing)系統軟件(jian)具有去除殘(can)渣(zha)、保持(chi)液(ye)(ye)體(ti)清潔的作用(yong)。當殘(can)渣(zha)的相對(dui)密(mi)(mi)(mi)度小于(yu)液(ye)(ye)體(ti)媒(mei)質相對(dui)密(mi)(mi)(mi)度時(shi)，能用(yong)過濾裝置去除殘(can)渣(zha)；而當殘(can)渣(zha)的相對(dui)密(mi)(mi)(mi)度超(chao)過液(ye)(ye)體(ti)媒(mei)質相對(dui)密(mi)(mi)(mi)度時(shi)，可選用(yong)旋液(ye)(ye)分(fen)離設備(bei)或網式過濾器去除殘(can)渣(zha)。

　　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。借助洞頭機械密封可以用雙端洞頭機械密封代替(ti)密(mi)(mi)封介(jie)質，將難以直(zhi)接密(mi)(mi)封的(de)(de)介(jie)質轉化為密(mi)(mi)封潤滑性能好(hao)、清潔的(de)(de)密(mi)(mi)封液(ye)體(ti)介(jie)質。