平定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。在平定機械密封系(xi)(xi)統(tong)(tong)(tong)(tong)(tong)中，上述系(xi)(xi)統(tong)(tong)(tong)(tong)(tong)并不同時包括在內。密(mi)(mi)封(feng)系(xi)(xi)統(tong)(tong)(tong)(tong)(tong)的(de)(de)選(xuan)擇主要取決于主密(mi)(mi)封(feng)件的(de)(de)應用(yong)(yong)范圍。例如，如果主密(mi)(mi)封(feng)用(yong)(yong)于高溫液體(ti)(ti)(ti)(ti)，密(mi)(mi)封(feng)系(xi)(xi)統(tong)(tong)(tong)(tong)(tong)應確保(bao)(bao)(bao)降(jiang)低主密(mi)(mi)封(feng)的(de)(de)環(huan)境(jing)溫度(du)，即采(cai)用(yong)(yong)溫度(du)控制系(xi)(xi)統(tong)(tong)(tong)(tong)(tong)。如果主密(mi)(mi)封(feng)用(yong)(yong)于固(gu)體(ti)(ti)(ti)(ti)雜(za)質(zhi)含量高的(de)(de)工作介質(zhi)，密(mi)(mi)封(feng)系(xi)(xi)統(tong)(tong)(tong)(tong)(tong)應確保(bao)(bao)(bao)在主密(mi)(mi)封(feng)前(qian)降(jiang)低固(gu)體(ti)(ti)(ti)(ti)雜(za)質(zhi)含量，即采(cai)用(yong)(yong)除雜(za)系(xi)(xi)統(tong)(tong)(tong)(tong)(tong)。在腐(fu)(fu)蝕(shi)性(xing)介質(zhi)中，密(mi)(mi)封(feng)系(xi)(xi)統(tong)(tong)(tong)(tong)(tong)必須確保(bao)(bao)(bao)主密(mi)(mi)封(feng)降(jiang)低腐(fu)(fu)蝕(shi)速率或消除腐(fu)(fu)蝕(shi)，即使用(yong)(yong)流(liu)體(ti)(ti)(ti)(ti)而不是堵塞流(liu)體(ti)(ti)(ti)(ti)系(xi)(xi)統(tong)(tong)(tong)(tong)(tong)；在高壓密(mi)(mi)封(feng)裝置中，輔助系(xi)(xi)統(tong)(tong)(tong)(tong)(tong)應確保(bao)(bao)(bao)多級降(jiang)壓和其他措施，即壓力控制系(xi)(xi)統(tong)(tong)(tong)(tong)(tong)。

　　平定機械密封的三(san)個主要功能如下：

　　1、沖洗功能，沖洗是平定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。一般的平定機械密封應該沖洗，特別(bie)是對(dui)于(yu)輕烴泵，沖洗時達到隔(ge)離介(jie)質(zhi)、冷卻(que)和改善潤滑的(de)(de)目(mu)(mu)的(de)(de)。隔(ge)離介(jie)質(zhi)的(de)(de)目(mu)(mu)的(de)(de)可以通過(guo)將與介(jie)質(zhi)相(xiang)容(rong)的(de)(de)液體引入(ru)密封腔進行外部循(xun)環(huan)沖洗來(lai)實現。

　　2、除雜和過濾功能，密封流體中的微細固體粒子、污垢等雜質對平定機械密封造成的(de)危害非常嚴重，可能導致密封端面(mian)的(de)磨損，也可能堵塞寒冷(leng)密封系(xi)統的(de)管線。密封性系(xi)統軟件(jian)具有去(qu)除(chu)(chu)殘渣(zha)、保持(chi)液體(ti)清潔(jie)的(de)作用。當(dang)殘渣(zha)的(de)相(xiang)(xiang)對(dui)(dui)密度(du)小于液體(ti)媒(mei)質(zhi)相(xiang)(xiang)對(dui)(dui)密度(du)時，能用過濾(lv)裝置去(qu)除(chu)(chu)殘渣(zha)；而當(dang)殘渣(zha)的(de)相(xiang)(xiang)對(dui)(dui)密度(du)超過液體(ti)媒(mei)質(zhi)相(xiang)(xiang)對(dui)(dui)密度(du)時，可選用旋液分離設備(bei)或網(wang)式過濾(lv)器去(qu)除(chu)(chu)殘渣(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。借助平定機械密封可以用雙端平定機械密封代替密封(feng)介(jie)質(zhi)，將難以直接密封(feng)的介(jie)質(zhi)轉化為密封(feng)潤滑性能好、清潔的密封(feng)液體介(jie)質(zhi)。