永嘉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。在永嘉機械密封系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)中(zhong)，上述系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)并不(bu)同(tong)時包括在(zai)(zai)內。密(mi)封(feng)(feng)系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)的(de)(de)選擇主(zhu)(zhu)要取決于(yu)主(zhu)(zhu)密(mi)封(feng)(feng)件(jian)的(de)(de)應用(yong)(yong)范圍。例如，如果主(zhu)(zhu)密(mi)封(feng)(feng)用(yong)(yong)于(yu)高溫(wen)(wen)液體(ti)，密(mi)封(feng)(feng)系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)應確(que)(que)保(bao)降低(di)主(zhu)(zhu)密(mi)封(feng)(feng)的(de)(de)環(huan)境(jing)溫(wen)(wen)度(du)，即采用(yong)(yong)溫(wen)(wen)度(du)控制系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)。如果主(zhu)(zhu)密(mi)封(feng)(feng)用(yong)(yong)于(yu)固(gu)體(ti)雜(za)質(zhi)含量高的(de)(de)工作介(jie)(jie)質(zhi)，密(mi)封(feng)(feng)系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)應確(que)(que)保(bao)在(zai)(zai)主(zhu)(zhu)密(mi)封(feng)(feng)前降低(di)固(gu)體(ti)雜(za)質(zhi)含量，即采用(yong)(yong)除雜(za)系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)。在(zai)(zai)腐蝕(shi)(shi)性介(jie)(jie)質(zhi)中(zhong)，密(mi)封(feng)(feng)系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)必須確(que)(que)保(bao)主(zhu)(zhu)密(mi)封(feng)(feng)降低(di)腐蝕(shi)(shi)速(su)率或消除腐蝕(shi)(shi)，即使用(yong)(yong)流(liu)體(ti)而不(bu)是堵(du)塞流(liu)體(ti)系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)；在(zai)(zai)高壓(ya)密(mi)封(feng)(feng)裝(zhuang)置中(zhong)，輔助系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)應確(que)(que)保(bao)多級降壓(ya)和(he)其(qi)他措(cuo)施，即壓(ya)力控制系(xi)(xi)(xi)(xi)統(tong)(tong)(tong)。

　　永嘉機械密封的(de)三個(ge)主(zhu)要功能如(ru)下(xia)：

　　1、沖洗功能，沖洗是永嘉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。一般的永嘉機械密封應該(gai)沖(chong)洗(xi)，特別是對于(yu)輕烴泵，沖(chong)洗(xi)時(shi)達(da)到(dao)隔離介質、冷卻和(he)改善潤滑的(de)目的(de)。隔離介質的(de)目的(de)可以通過將(jiang)與介質相(xiang)容的(de)液(ye)體(ti)引入密封腔(qiang)進(jin)行外部循環(huan)沖(chong)洗(xi)來實現(xian)。

　　2、除雜和過濾功能，密封流體中的微細固體粒子、污垢等雜質對永嘉機械密封造成的危害(hai)非常(chang)嚴(yan)重，可能導致(zhi)密(mi)封(feng)端(duan)面的磨損，也可能堵塞寒冷密(mi)封(feng)系(xi)統(tong)的管線。密(mi)封(feng)性系(xi)統(tong)軟件具有去(qu)除殘(can)(can)渣、保(bao)持液(ye)體清潔(jie)的作用(yong)。當殘(can)(can)渣的相對密(mi)度(du)小(xiao)于液(ye)體媒質(zhi)(zhi)相對密(mi)度(du)時，能用(yong)過濾裝置去(qu)除殘(can)(can)渣；而當殘(can)(can)渣的相對密(mi)度(du)超過液(ye)體媒質(zhi)(zhi)相對密(mi)度(du)時，可選(xuan)用(yong)旋液(ye)分離設備或網式過濾器去(qu)除殘(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。借助永嘉機械密封可以用雙端永嘉機械密封代替(ti)密(mi)封(feng)介質(zhi)，將(jiang)難以直接密(mi)封(feng)的介質(zhi)轉化為密(mi)封(feng)潤滑性能好、清潔(jie)的密(mi)封(feng)液體介質(zhi)。