測量柴油凝點時觀察試(shi)樣的流動性(xing)

試(shi)(shi)(shi)(shi)樣從高于預期傾(qing)點9C(估(gu)算為3C倍(bei)數)開始觀察試(shi)(shi)(shi)(shi)樣的(de)流動性(xing)。每當溫(wen)(wen)(wen)度計讀數降低(di)3C°時(shi)，要(yao)(yao)小心地把(ba)試(shi)(shi)(shi)(shi)管(guan)(guan)從冷(leng)浴(yu)中(zhong)取出，將試(shi)(shi)(shi)(shi)管(guan)(guan)充分傾(qing)斜以確定試(shi)(shi)(shi)(shi)樣是(shi)否(fou)流動。取出試(shi)(shi)(shi)(shi)管(guan)(guan)、觀察試(shi)(shi)(shi)(shi)樣流動性(xing)和返回(hui)到(dao)浴(yu)中(zhong)的(de)全部操作要(yao)(yao)求不超過3S。如(ru)果溫(wen)(wen)(wen)度已(yi)降到(dao)9C°，試(shi)(shi)(shi)(shi)樣仍流動，則(ze)將試(shi)(shi)(shi)(shi)管(guan)(guan)移到(dao)溫(wen)(wen)(wen)度保持在(zai)(zai)-18~-15C°的(de)冷(leng)浴(yu)套(tao)(tao)管(guan)(guan)中(zhong);如(ru)果溫(wen)(wen)(wen)度已(yi)降到(dao)-6C°，試(shi)(shi)(shi)(shi)樣仍流動，則(ze)將試(shi)(shi)(shi)(shi)管(guan)(guan)移到(dao)溫(wen)(wen)(wen)度保持在(zai)(zai)-35~ -32C的(de)冷(leng)浴(yu)套(tao)(tao)管(guan)(guan)中(zhong)。測定極低(di)的(de)傾(qing)點時(shi)，需(xu)要(yao)(yao)多個不同溫(wen)(wen)(wen)度的(de)冷(leng)浴(yu)，每個冷(leng)浴(yu)間的(de)溫(wen)(wen)(wen)差為17C°，如(ru)-52~-49C°、 -69~-66C*和-86~-83C°等。當傾(qing)斜試(shi)(shi)(shi)(shi)管(guan)(guan)，發現試(shi)(shi)(shi)(shi)樣不流動時(shi)，就立即(ji)(ji)將試(shi)(shi)(shi)(shi)管(guan)(guan)放在(zai)(zai)水平位置上仔(zi)細觀察試(shi)(shi)(shi)(shi)樣的(de)表面，如(ru)果在(zai)(zai)5s內(nei)還有流動，則(ze)立即(ji)(ji)將試(shi)(shi)(shi)(shi)管(guan)(guan)放回(hui)冷(leng)浴(yu)，待再(zai)降低(di)3C°時(shi)，重復進行流動試(shi)(shi)(shi)(shi)驗。