油(you)品的(de)傾點與凝(ning)點  

傾點:油樣在標(biao)準(zhun)規定的條件下冷卻時，能夠(gou)繼(ji)續流動(dong)的zui低(di)溫度稱(cheng)為傾點。

凝點:油(you)樣在規定試(shi)驗條(tiao)件(jian)下冷卻到液面不移動(dong)時的最(zui)高(gao)溫(wen)度稱為凝點。

傾(qing)點(dian)(dian)是用(yong)(yong)(yong)來衡量(liang)(liang)(liang)潤(run)滑(hua)油(you)(you)(you)等低(di)(di)(di)溫(wen)(wen)流(liu)動(dong)(dong)性(xing)(xing)(xing)的(de)(de)常規指(zhi)標，同一油(you)(you)(you)品(pin)(pin)的(de)(de)傾(qing)點(dian)(dian)比(bi)凝(ning)(ning)點(dian)(dian)略高(gao)幾度(du)(du)(du)，過(guo)去(qu)常用(yong)(yong)(yong)凝(ning)(ning)點(dian)(dian)，國際通用(yong)(yong)(yong)傾(qing)點(dian)(dian)。傾(qing)點(dian)(dian)或(huo)凝(ning)(ning)點(dian)(dian)偏(pian)高(gao)，油(you)(you)(you)品(pin)(pin)的(de)(de)低(di)(di)(di)溫(wen)(wen)流(liu)動(dong)(dong)性(xing)(xing)(xing)就差。人們可(ke)以(yi)(yi)根(gen)據油(you)(you)(you)品(pin)(pin)傾(qing)點(dian)(dian)的(de)(de)高(gao)低(di)(di)(di)，考慮在(zai)低(di)(di)(di)溫(wen)(wen)條件(jian)下(xia)運輸、儲存、收發時(shi)應(ying)該采取的(de)(de)措施，也可(ke)以(yi)(yi)用(yong)(yong)(yong)來評(ping)估(gu)某些油(you)(you)(you)品(pin)(pin)的(de)(de)低(di)(di)(di)溫(wen)(wen)使(shi)用(yong)(yong)(yong)性(xing)(xing)(xing)能。石油(you)(you)(you)產(chan)品(pin)(pin)是多種(zhong)烴(jing)類的(de)(de)復雜(za)混合物(wu)，每(mei)一種(zhong)烴(jing)都有(you)(you)它的(de)(de)凝(ning)(ning)點(dian)(dian)，因此當溫(wen)(wen)度(du)(du)(du)降(jiang)(jiang)低(di)(di)(di)時(shi)，油(you)(you)(you)品(pin)(pin)并(bing)不(bu)(bu)立即凝(ning)(ning)固，要(yao)經過(guo)一-個稠化(hua)階段(duan)，在(zai)相當寬的(de)(de)溫(wen)(wen)度(du)(du)(du)內逐漸(jian)凝(ning)(ning)固，所以(yi)(yi)同-一個試樣(yang)的(de)(de)傾(qing)點(dian)(dian)比(bi)凝(ning)(ning)點(dian)(dian)約高(gao).3~5"C左(zuo)右。含(han)蠟(la)(la)(la)油(you)(you)(you)品(pin)(pin)之所以(yi)(yi)在(zai)低(di)(di)(di)溫(wen)(wen)下(xia)失(shi)去(qu)流(liu)動(dong)(dong)性(xing)(xing)(xing)，是由(you)于高(gao)熔(rong)點(dian)(dian)的(de)(de)石蠟(la)(la)(la)烴(jing)(除正構(gou)烴(jing)外(wai)，尚包含(han)少(shao)量(liang)(liang)(liang)異(yi)構(gou)和(he)環狀(zhuang)(zhuang)烴(jing))以(yi)(yi)針(zhen)狀(zhuang)(zhuang)或(huo)片狀(zhuang)(zhuang)結晶(jing)析出(chu)，并(bing)互相黏(nian)結,形成(cheng)(cheng)三(san)維網狀(zhuang)(zhuang)結構(gou)，將低(di)(di)(di)熔(rong)點(dian)(dian)油(you)(you)(you)吸(xi)附(fu)并(bing)包于其中，致(zhi)使(shi)整個油(you)(you)(you)品(pin)(pin)喪失(shi)流(liu)動(dong)(dong)性(xing)(xing)(xing)。含(han)蠟(la)(la)(la)油(you)(you)(you)品(pin)(pin)降(jiang)(jiang)低(di)(di)(di)傾(qing)點(dian)(dian)途徑有(you)(you)兩條:一是對基礎油(you)(you)(you)進(jin)(jin)行深度(du)(du)(du)脫(tuo)(tuo)蠟(la)(la)(la)，可(ke)以(yi)(yi)得到(dao)低(di)(di)(di)傾(qing)點(dian)(dian)潤(run)滑(hua)油(you)(you)(you)，這樣(yang)油(you)(you)(you)品(pin)(pin)的(de)(de)收率低(di)(di)(di)，成(cheng)(cheng)本高(gao)，同時(shi)脫(tuo)(tuo)掉大量(liang)(liang)(liang)的(de)(de)正構(gou)烴(jing)，也有(you)(you)損油(you)(you)(you)品(pin)(pin)的(de)(de)質(zhi)量(liang)(liang)(liang);二是進(jin)(jin)行適度(du)(du)(du)的(de)(de)脫(tuo)(tuo)蠟(la)(la)(la)后，再加(jia)降(jiang)(jiang)凝(ning)(ning)劑達到(dao)所要(yao)求(qiu)的(de)(de)傾(qing)點(dian)(dian)。降(jiang)(jiang)凝(ning)(ning)劑不(bu)(bu)能阻止石蠟(la)(la)(la)烴(jing)在(zai)低(di)(di)(di)溫(wen)(wen)下(xia)結晶(jing)析出(chu)，而是通過(guo)吸(xi)附(fu)或(huo)共晶(jing)作用(yong)(yong)(yong)，防止石蠟(la)(la)(la)烴(jing)形成(cheng)(cheng)三(san)維網狀(zhuang)(zhuang)結晶(jing)而失(shi)去(qu)流(liu)動(dong)(dong)性(xing)(xing)(xing)。不(bu)(bu)同的(de)(de)潤(run)滑(hua)油(you)(you)(you)對降(jiang)(jiang)凝(ning)(ning)劑有(you)(you)不(bu)(bu)同的(de)(de)感受性(xing)(xing)(xing)，加(jia)入量(liang)(liang)(liang)不(bu)(bu)足或(huo)過(guo)量(liang)(liang)(liang)都不(bu)(bu)能達到(dao)理想(xiang)的(de)(de)降(jiang)(jiang)凝(ning)(ning)效果。