ASTM D5949 Test Method for Pour Point of Petroleum Products (Automatic Pressure Pulsing Method)
4. Summary of Test Method
4.1 After inserting the test specimen into the automatic pour point apparatus, and initiation of the test program, the test specimen is heated and then cooled by a Peltier device at a rate of 1.5 °C/min +/- 0.1 °C/min. At temperature intervals of 1 °C or 3 °C, depending on the selection made by the user, a moving force in the form of a pressurized pulse of compressed gas is imparted onto the surface of the specimen. Multiple optical detectors are used in conjunction with a light source to monitor movement of the surface of the specimen. The lowest temperature at which movement of the specimen surface is observed upon application of a pulse of compressed gas is recorded as the pour point, Test Method D5949.
5. Significance and Use
5.1 The pour point of a petroleum product is an index of the lowest temperature of its utility for certain applications. Flow characteristics, like pour point, can be critical for the correct operation of lubricating oil systems, fuel systems, and pipeline operations.
5.2 Petroleum blending operations require precise measurement of the pour point.
5.3 In most cases, this test method does not require the use of mechanical refrigeration apparatus (see 7.1).
5.4 This test method yields a pour point in a format similar to Test Method D97/IP 15 when the 3 °C interval results are reported.
NOTE 2 - Since some users may wish to report their results in a format similar to Test Method D97 (in 3 °C intervals) the precisions were derived from the temperatures rounded to the 3° intervals. For statements on bias relative to Test Method D97, see 13.3.
5.5 Test results from this test method can be determined at either 1 °C or 3 °C intervals.
5.6 This test method has better repeatability and reproducibility relative to Test Method D97/IP 15 as measured in the 1992 and 1998 interlaboratory test programs.
