Cloud point refers to the high temperature at which the oil begins to appear turbid by the appearance of hydrocarbon microcrystals or water mist under the test conditions. After the oil has a cloud point, continue to cool until the oil shows crystals visible to the naked eye. The temperature at this time is the crystallization point of the oil, commonly known as the freezing point. Pour point refers to the low temperature at which petroleum products can flow out of a standard type container during the cooling process. The freezing point refers to the temperature at which the oil loses its fluidity (the test tube is tilted at an angle of 45°, after one minute, no movement of the oil surface is visible to the naked eye) measured under certain test conditions in the specified instrument. The essence of the freezing point is that the viscosity of the oil increases at low temperatures, forming an amorphous glassy substance that loses fluidity or waxy oil wax crystallizes in large quantities, connected into a network structure, and the crystalline skeleton encloses the liquid oil. Make it lose liquidity. The cloud point of the same oil is higher than the freezing point, and the freezing point is higher than the freezing point. The high cloud point and crystallization point indicate that the fuel has poor low temperature properties. Crystals will precipitate at higher temperatures, clogging the filter, hindering or even interrupting the fuel supply. Therefore, aviation gasoline and aviation kerosene specifications have strict regulations on cloud point and crystallization point.
