傾(qing)點(dian)、凝點(dian)及測試方(fang)法(fa)

潤滑油試(shi)樣在規定(ding)的(de)(de)試(shi)驗條(tiao)件(jian)下(xia)冷卻(que)至停止(zhi)流(liu)動時的(de)(de)最高(gao)溫(wen)度稱(cheng)為凝(ning)(ning)點(dian)(dian)(dian)。而(er)試(shi)樣在規定(ding)的(de)(de)試(shi)驗條(tiao)件(jian)下(xia)，被(bei)冷卻(que)的(de)(de)試(shi)樣能夠(gou)流(liu)動的(de)(de)zui低溫(wen)度稱(cheng)為傾(qing)點(dian)(dian)(dian)。凝(ning)(ning)點(dian)(dian)(dian)和傾(qing)點(dian)(dian)(dian)都(dou)是(shi)(shi)表示油品低溫(wen)流(liu)動性的(de)(de)指標，二者(zhe)無原則差別(bie)，只是(shi)(shi)測定(ding)方法有所(suo)不同(tong)。同(tong)一(yi)試(shi)樣測得的(de)(de)凝(ning)(ning)點(dian)(dian)(dian)和傾(qing)點(dian)(dian)(dian)并(bing)不是(shi)(shi)全相(xiang)等，一(yi)般傾(qing)點(dian)(dian)(dian)都(dou)高(gao)于凝(ning)(ning)點(dian)(dian)(dian)2-3°C，但也(ye)有兩者(zhe)相(xiang)等或傾(qing)點(dian)(dian)(dian)低于凝(ning)(ning)點(dian)(dian)(dian)的(de)(de)情況。國外(wai)常用傾(qing)點(dian)(dian)(dian)(流(liu)動點(dian)(dian)(dian))，我國也(ye)一(yi)般采(cai)用傾(qing)點(dian)(dian)(dian)這個標準。

溫(wen)度(du)很低時，粘(zhan)度(du)變(bian)大，甚至變(bian)成無定(ding)型的玻璃(li)狀物(wu)質，失去流動性(xing)。因此在生產、運輸和使用潤(run)滑(hua)油時因根據環境條件和工況選(xuan)用相適(shi)應的傾點(或(huo)傾點)。

(1)潤滑油凝點(dian)測(ce)(ce)定(ding)法(fa)(GB/T 510)測(ce)(ce)定(ding)的(de)基本過(guo)程是:將試(shi)(shi)樣(yang)裝入試(shi)(shi)管(guan)(guan)中(zhong)，按(an)規定(ding)的(de)預(yu)處理步驟和冷(leng)(leng)卻速度(du)進行(xing)(xing)試(shi)(shi)驗(yan)(yan)。當試(shi)(shi)樣(yang)溫(wen)(wen)度(du)冷(leng)(leng)卻到預(yu)期(qi)的(de)凝點(dian)時(shi)，將在冷(leng)(leng)劑中(zhong)的(de)儀器傾斜45度(du)保持1min后(hou)，取出(chu)觀察試(shi)(shi)管(guan)(guan)里面的(de)液(ye)面是否有(you)(you)過(guo)移(yi)(yi)(yi)(yi)動(dong)(dong)(dong)(dong)的(de)跡象。如有(you)(you)移(yi)(yi)(yi)(yi)動(dong)(dong)(dong)(dong)時(shi)，從套管(guan)(guan)中(zhong)取出(chu)試(shi)(shi)管(guan)(guan)，并(bing)將試(shi)(shi)管(guan)(guan)重(zhong)(zhong)新預(yu)熱，然后(hou)用比(bi)上次試(shi)(shi)驗(yan)(yan)溫(wen)(wen)度(du)低(di)4°C或(huo)其(qi)它更(geng)低(di)的(de)溫(wen)(wen)度(du)重(zhong)(zhong)新進行(xing)(xing)測(ce)(ce)定(ding)，直(zhi)至某試(shi)(shi)驗(yan)(yan)溫(wen)(wen)度(du)時(shi)液(ye)面位(wei)置停止移(yi)(yi)(yi)(yi)動(dong)(dong)(dong)(dong)為(wei)止。如沒有(you)(you)移(yi)(yi)(yi)(yi)動(dong)(dong)(dong)(dong)，從套管(guan)(guan)中(zhong)取出(chu)試(shi)(shi)管(guan)(guan)，并(bing)將試(shi)(shi)管(guan)(guan)重(zhong)(zhong)新預(yu)熱，然后(hou)用比(bi)上次試(shi)(shi)驗(yan)(yan)溫(wen)(wen)度(du)高(gao)4°C或(huo)其(qi)它更(geng)高(gao)的(de)溫(wen)(wen)度(du)重(zhong)(zhong)新進行(xing)(xing)測(ce)(ce)定(ding)，直(zhi)至某試(shi)(shi)驗(yan)(yan)溫(wen)(wen)度(du)時(shi)液(ye)面位(wei)置有(you)(you)了移(yi)(yi)(yi)(yi)動(dong)(dong)(dong)(dong)為(wei)止。找出(chu)凝點(dian)的(de)溫(wen)(wen)度(du)范圍(即液(ye)面位(wei)置從移(yi)(yi)(yi)(yi)動(dong)(dong)(dong)(dong)到不移(yi)(yi)(yi)(yi)動(dong)(dong)(dong)(dong)或(huo)從不移(yi)(yi)(yi)(yi)動(dong)(dong)(dong)(dong)到移(yi)(yi)(yi)(yi)動(dong)(dong)(dong)(dong)的(de)溫(wen)(wen)度(du)范圍)之后(hou)，采(cai)(cai)用比(bi)移(yi)(yi)(yi)(yi)動(dong)(dong)(dong)(dong)的(de)溫(wen)(wen)度(du)低(di)2°C或(huo)采(cai)(cai)用比(bi)不移(yi)(yi)(yi)(yi)動(dong)(dong)(dong)(dong)的(de)溫(wen)(wen)度(du)高(gao)2°C，重(zhong)(zhong)新

進行試驗(yan)，直至確(que)定某試驗(yan)溫度能(neng)使(shi)試樣(yang)的液面(mian)停留不動(dong)(dong)而提(ti)高(gao)2°C又能(neng)使(shi)液面(mian)移動(dong)(dong)時，就取使(shi)液面(mian)不動(dong)(dong)的溫度作為試樣(yang)的凝點。

(2)潤滑油傾(qing)點測(ce)定法(GB/T 3535)試(shi)(shi)驗(yan)的(de)基本過程是:將清潔的(de)試(shi)(shi)樣(yang)注入試(shi)(shi)管中，按方法所(suo)規(gui)定的(de)步驟進行試(shi)(shi)驗(yan)。對傾(qing)點高于(yu)33°C的(de)試(shi)(shi)樣(yang)，試(shi)(shi)驗(yan)從(cong)高于(yu)預期的(de)傾(qing)點9°C開(kai)始，對其(qi)它的(de)傾(qing)點試(shi)(shi)樣(yang)則(ze)從(cong)高于(yu)其(qi)傾(qing)點12°C開(kai)始。每當溫度計讀數為3°C的(de)倍數時，要小心地把試(shi)(shi)管從(cong)套管中

取(qu)出(chu)(chu)，傾(qing)斜試(shi)(shi)(shi)管(guan)到剛好能(neng)觀察到試(shi)(shi)(shi)管(guan)內(nei)試(shi)(shi)(shi)樣是(shi)否流(liu)動(dong)(dong)，取(qu)出(chu)(chu)試(shi)(shi)(shi)管(guan)到放(fang)回試(shi)(shi)(shi)管(guan)的全部(bu)操作要求不超過3s。當傾(qing)斜試(shi)(shi)(shi)管(guan)，發現試(shi)(shi)(shi)樣不流(liu)動(dong)(dong)時(shi)，就(jiu)立即將(jiang)試(shi)(shi)(shi)管(guan)放(fang)在水平位置上，仔細觀察試(shi)(shi)(shi)樣的表面(mian)，如果在5s內(nei)還有(you)流(liu)動(dong)(dong)，則立即將(jiang)試(shi)(shi)(shi)管(guan)放(fang)回套管(guan)，待(dai)溫度降(jiang)低3°C時(shi)，重復進行流(liu)動(dong)(dong)

試(shi)驗，直到試(shi)管(guan)保(bao)持水平位置5s而試(shi)樣(yang)無流動時，紀錄觀察(cha)到的試(shi)驗溫度計讀數，再加3°C作為試(shi)樣(yang)的傾點。