Diesel fuel’s freezing point and cold filter plugging point

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For the same oil, the cold filter point is generally 1°C to 3°C higher than the freezing point. By using the dewaxing method, the freezing point can be reduced to obtain low-freezing diesel. 　　Oil does not have a definite freezing temperature. The freezing point is the highest temperature at which all liquid fluids cease to flow under specified cooling conditions. 　　The solidification of oils differs greatly from that of pure compounds. Oil does not have a definite freezing temperature; the so-called “freezing” simply means that it loses its fluidity as a whole, and not all of its components turn into solids. 　　The cold filter point refers to the highest temperature under specified conditions, when less than 20 ml of the oil sample passes through the filter per minute (i.e., the lowest ambient temperature used for the flow point). 　　According to the national standard (GB252—87), light diesel is classified into six grades based on its freezing point: 10, 0, -10, -20, -35, and -50. These grades indicate that the freezing point is no higher than 10°C, 0°C, -10°C, -20°C, -35°C, and -50°C respectively℃ ； The higher the grade, the lower the freezing point. 　　The cold filter point is an important indicator for measuring the low-temperature performance of light diesel; it reflects the actual performance of diesel at low temperatures and is closest to the actual lowest operating temperature of diesel. When selecting a diesel grade, users should take into account both the local temperature and the cold filter plugging point corresponding to that diesel grade. The cold filter point of No. 5 light diesel is 8°C, that of No. 0 light diesel is 4°C, that of No. -10 light diesel is -5°C, and that of No. -20 light diesel is -14°C℃