雙流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。在雙流機械密封系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)中(zhong)，上述(shu)系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)并(bing)不同(tong)時包括在內。密(mi)封系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)的(de)選擇主(zhu)(zhu)(zhu)要取決于(yu)主(zhu)(zhu)(zhu)密(mi)封件的(de)應(ying)用(yong)(yong)范圍。例如(ru)，如(ru)果主(zhu)(zhu)(zhu)密(mi)封用(yong)(yong)于(yu)高(gao)溫(wen)(wen)液體(ti)(ti)，密(mi)封系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)應(ying)確保(bao)降(jiang)低主(zhu)(zhu)(zhu)密(mi)封的(de)環境溫(wen)(wen)度，即采(cai)用(yong)(yong)溫(wen)(wen)度控制系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)。如(ru)果主(zhu)(zhu)(zhu)密(mi)封用(yong)(yong)于(yu)固(gu)體(ti)(ti)雜(za)(za)(za)質(zhi)含(han)(han)量高(gao)的(de)工(gong)作(zuo)介質(zhi)，密(mi)封系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)應(ying)確保(bao)在主(zhu)(zhu)(zhu)密(mi)封前降(jiang)低固(gu)體(ti)(ti)雜(za)(za)(za)質(zhi)含(han)(han)量，即采(cai)用(yong)(yong)除雜(za)(za)(za)系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)。在腐蝕(shi)性介質(zhi)中(zhong)，密(mi)封系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)必須(xu)確保(bao)主(zhu)(zhu)(zhu)密(mi)封降(jiang)低腐蝕(shi)速率或消除腐蝕(shi)，即使用(yong)(yong)流(liu)體(ti)(ti)而不是堵塞流(liu)體(ti)(ti)系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)；在高(gao)壓密(mi)封裝置中(zhong)，輔助(zhu)系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)應(ying)確保(bao)多級降(jiang)壓和(he)其他措(cuo)施(shi)，即壓力控制系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)。

　　雙流機械密封的三(san)個主要功能如下(xia)：

　　1、沖洗功能，沖洗是雙流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。一般的雙流機械密封應該沖洗(xi)(xi)，特(te)別(bie)是對于(yu)輕烴泵，沖洗(xi)(xi)時(shi)達(da)到隔離(li)介質(zhi)、冷卻和改(gai)善潤滑(hua)的(de)目(mu)的(de)。隔離(li)介質(zhi)的(de)目(mu)的(de)可以通過(guo)將與(yu)介質(zhi)相容的(de)液體引入(ru)密封腔進行外部循環(huan)沖洗(xi)(xi)來實現。

　　2、除雜和過濾功能，密封流體中的微細固體粒子、污垢等雜質對雙流機械密封造成(cheng)的(de)(de)(de)危害非常嚴(yan)重(zhong)，可能(neng)導致密(mi)(mi)封(feng)端面(mian)的(de)(de)(de)磨(mo)損(sun)，也可能(neng)堵塞寒冷密(mi)(mi)封(feng)系統(tong)的(de)(de)(de)管線。密(mi)(mi)封(feng)性系統(tong)軟件(jian)具有去(qu)除殘(can)(can)渣(zha)(zha)(zha)、保持液(ye)體清潔的(de)(de)(de)作用。當殘(can)(can)渣(zha)(zha)(zha)的(de)(de)(de)相對密(mi)(mi)度(du)小于液(ye)體媒(mei)質(zhi)相對密(mi)(mi)度(du)時，能(neng)用過(guo)(guo)濾(lv)裝置去(qu)除殘(can)(can)渣(zha)(zha)(zha)；而當殘(can)(can)渣(zha)(zha)(zha)的(de)(de)(de)相對密(mi)(mi)度(du)超過(guo)(guo)液(ye)體媒(mei)質(zhi)相對密(mi)(mi)度(du)時，可選用旋(xuan)液(ye)分離設備或(huo)網式(shi)過(guo)(guo)濾(lv)器去(qu)除殘(can)(can)渣(zha)(zha)(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。借助雙流機械密封可以用雙端雙流機械密封代替密(mi)封(feng)(feng)介質(zhi)，將難(nan)以(yi)直接(jie)密(mi)封(feng)(feng)的(de)(de)介質(zhi)轉化(hua)為密(mi)封(feng)(feng)潤滑性能好、清(qing)潔的(de)(de)密(mi)封(feng)(feng)液體介質(zhi)。