ASTM D5772 Standard Test Method for Cloud Point of Petroleum Products and Liquid Fuels (Linear Cooling Rate Method)
4. Summary of Test Method
4.1 After insertion of the specimen into the apparatus and initiation of the program, the prescribed specimen test cell (Annex A1) is heated and then linearly cooled at a specified rate (11.6). The specimen is continuously monitored by an opposing optical light barrier (Annex A1 and Fig. A1.3) for the crystal structure formation. The temperature, when the crystallization of the wax in the specimen is detected by the optical barrier, is recorded with a resolution of 0.1 °C. The specimen is then heated to the original starting temperature.
5. Significance and Use
5.1 For petroleum products and diesel fuels, the cloud point is an index of the lowest temperature of its utility for certain applications. Wax crystals of sufficient quantity can plug filters used in some fuel systems.
5.2 Petroleum blending operations require precise measurement of the cloud point.
5.3 This test method can determine the temperature of the test specimen at which wax crystals have formed sufficiently to be observed as a cloud, with a resolution of 0.1 °C.
5.4 This test method provides results that when rounded to the next lower integer are equivalent to Test Method D2500.
5.5 This test method is more precise than Test Method D2500.
