油品知識柴(chai)油的油點(dian)凝點(dian)和冷(leng)濾(lv)點(dian)及保質(zhi)期(qi)

油(you)(you)品(pin)知識柴油(you)(you)的(de)(de)油(you)(you)點凝點和冷濾點及保質期所謂濁(zhuo)(zhuo)點就(jiu)是油(you)(you)品(pin)在(zai)實驗(yan)條件下，開(kai)始出現烴類的(de)(de)微晶粒或水霧而使(shi)油(you)(you)品(pin)呈現渾濁(zhuo)(zhuo)時的(de)(de)最高(gao)溫度(du)。有些國家用濁(zhuo)(zhuo)點作為柴油(you)(you)的(de)(de)牌號。

油(you)品是-種復雜的(de)混合物(wu)，它沒有(you)固定的(de)“凝(ning)(ning)點"。所(suo)謂油(you)品的(de)“凝(ning)(ning)點'是在規(gui)定的(de)儀器中,按一定的(de)實驗(yan)條(tiao)(tiao)件(jian)測得油(you)品失去流動(dong)性(xing)時(shi)(shi)的(de)最高(gao)溫度。而所(suo)謂失去流動(dong)性(xing)，也是條(tiao)(tiao)件(jian)性(xing)的(de)，即在油(you)品冷卻到某(mou)一溫度時(shi)(shi)， 把裝有(you)試油(you)的(de)規(gui)定試管(guan)傾(qing)斜(xie)45°，經過(guo)1min后,肉眼(yan)看不(bu)出試管(guan)內油(you)面有(you)所(suo)移(yi)動(dong)，此(ci)時(shi)(shi)就認為(wei)油(you)品“凝(ning)(ning)固"了。我國(guo)用凝(ning)(ning)點作為(wei)輕柴油(you)的(de)牌(pai)號。英美各(ge)國(guo)是

把(ba)裝有試油的(de)規定(ding)瓶子(zi)轉成水平的(de)位置,經過5S后液體(ti)不再(zai)移(yi)動的(de)最(zui)高溫度稱(cheng)為“凝(ning)點(dian)"。這兩種方法測定(ding)的(de)油品凝(ning)點(dian)大致相同。

由于(yu)凝點(dian)(dian)(dian)(dian)不(bu)能(neng)夠直(zhi)接表(biao)征柴(chai)(chai)油(you)在低溫(wen)(wen)下(xia)(xia)(xia)堵(du)塞發動機濾(lv)網(wang)(wang)的(de)(de)可能(neng)性(xing), - -般選用柴(chai)(chai)油(you)的(de)(de)凝點(dian)(dian)(dian)(dian)需低于(yu)環境溫(wen)(wen)度(du)3~5°C，在實際(ji)使(shi)用中(zhong)，柴(chai)(chai)油(you)在低溫(wen)(wen)下(xia)(xia)(xia)會(hui)析出(chu)結晶體(ti)，晶體(ti)長大到一定程度(du)就會(hui)堵(du)塞濾(lv)網(wang)(wang)，因而提出(chu)“冷濾(lv)點(dian)(dian)(dian)(dian)"這(zhe)一指標。與凝點(dian)(dian)(dian)(dian)相比，它(ta)更能(neng)反映柴(chai)(chai)油(you)的(de)(de)實際(ji)使(shi)用性(xing)能(neng)。冷濾(lv)點(dian)(dian)(dian)(dian)的(de)(de)測定方法是規(gui)定壓力和一定冷卻溫(wen)(wen)度(du)下(xia)(xia)(xia)測定20mL試(shi)油(you)開始不(bu)能(neng)通過規(gui)定濾(lv)網(wang)(wang)時(shi)的(de)(de)最高溫(wen)(wen)度(du),這(zhe)個溫(wen)(wen)度(du)稱(cheng)為(wei)冷濾(lv)點(dian)(dian)(dian)(dian)。對(dui)同一油(you)品(pin)，-般冷濾(lv)點(dian)(dian)(dian)(dian)高1~3°C。采用脫蠟的(de)(de)方法，可降(jiang)低濾(lv)點(dian)(dian)(dian)(dian)，得到低濾(lv)柴(chai)(chai)油(you)。

柴(chai)(chai)(chai)油(you)(you)(you)(you)濁(zhuo)點(dian)(dian)(dian)(dian)冷(leng)濾(lv)(lv)(lv)點(dian)(dian)(dian)(dian)和凝(ning)(ning)點(dian)(dian)(dian)(dian)是對柴(chai)(chai)(chai)油(you)(you)(you)(you)低(di)(di)(di)溫流動性的(de)(de)(de)要(yao)求。隨(sui)著溫度不(bu)斷(duan)降低(di)(di)(di)，柴(chai)(chai)(chai)油(you)(you)(you)(you)蠟結晶(jing)從出(chu)現、積聚直至凝(ning)(ning)固(gu)，造成過濾(lv)(lv)(lv)器阻(zu)塞，使發動機無法運(yun)轉(zhuan)。濁(zhuo)點(dian)(dian)(dian)(dian)冷(leng)濾(lv)(lv)(lv)點(dian)(dian)(dian)(dian)和凝(ning)(ning)點(dian)(dian)(dian)(dian)的(de)(de)(de)高低(di)(di)(di)與柴(chai)(chai)(chai)油(you)(you)(you)(you)的(de)(de)(de)組成有(you)關，烷烴(jing)最高,芳烴(jing)zui低(di)(di)(di)。一般認(ren)為(wei)冷(leng) 濾(lv)(lv)(lv)點(dian)(dian)(dian)(dian)能夠比較實際地(di)反映使用時的(de)(de)(de)氣(qi)候(hou)條件。因此,我國(guo)輕柴(chai)(chai)(chai)油(you)(you)(you)(you)標準GB252- -2000規定(ding) 了7種(zhong)牌號(hao)柴(chai)(chai)(chai)油(you)(you)(you)(you)的(de)(de)(de)冷(leng)濾(lv)(lv)(lv)點(dian)(dian)(dian)(dian)要(yao)求,開始逐漸用冷(leng)濾(lv)(lv)(lv)點(dian)(dian)(dian)(dian)代替柴(chai)(chai)(chai)油(you)(you)(you)(you)凝(ning)(ning)點(dian)(dian)(dian)(dian)作為(wei)油(you)(you)(you)(you)品的(de)(de)(de)低(di)(di)(di)溫流動性指標。美國(guo)柴(chai)(chai)(chai)油(you)(you)(you)(you)規格(ge)的(de)(de)(de)濁(zhuo)點(dian)(dian)(dian)(dian)根據美國(guo)各(ge)州月(yue)風險率10%的(de)(de)(de)zui低(di)(di)(di)溫度規定(ding);歐洲柴(chai)(chai)(chai)油(you)(you)(you)(you)規格(ge)根據不(bu)同氣(qi)候(hou)分(fen)別規定(ding)冷(leng)濾(lv)(lv)(lv)點(dian)(dian)(dian)(dian)和濁(zhuo)點(dian)(dian)(dian)(dian)。