ASTM D5949 Test Method for Pour Point of Petroleum Products (Automatic Pressure Pulsing Method)
1. Scope
1.1 This test method covers the determination of pour point of petroleum products by an automatic instrument that applies a controlled burst of nitrogen gas onto the specimen surface while the specimen is being cooled and detects movement of the surface of the test specimen with an optical device.
1.2 This test method is designed to cover the range of temperatures from -57 °C to +51 °C. However, the range of temperatures included in the 1992 interlaboratory test program only covered the temperature range from -39 °C to +6 °C and the range of temperatures included in the 1998 interlaboratory test program was from -51 °C to -11 °C. (see 13.4).
1.3 Test results from this test method can be determined at 1 °C or 3 °C testing intervals.
1.4 This test method is not intended for use with crude oils.
NOTE 1 - The applicability of this test method or residual fuel samples has not been verified. For further information on applicability, refer to 13.4.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
D97 Test Method for Pour Point of Petroleum Products
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
D6708 Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
2.2 Energy Institute Standard:
IP 15 Test Method for Pour Point of Petroleum Products
3. Terminology
3.1 Definitions:
3.1.1 pour point, n - in petroleum products, the lowest temperature at which movement of the test specimen is observed under the prescribed conditions of the test.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 no-flow point, n - in petroleum products, the temperature of the test specimen at which a wax crystal structure or viscosity increase, or both, impedes movement of the surface of the test specimen under the conditions of the test.
3.2.1.1 Discussion - The no-flow point occurs when, upon cooling, the formation of wax crystal structures or viscosity increase, or both, has progressed to the point where the applied observation device no longer detects movement under the conditions of the test. The preceding observation temperature, at which flow of the test specimen is last observed, is the pour point.
3.2.2 pulse, n - a controlled burst of nitrogen gas of a fixed pressure and flow rate sufficient to cause movement on the surface of the test specimen without fracturing the wax structure which may be formed in the specimen.
3.2.3 Peltier device, n - a solid-state thermoelectric device constructed with dissimilar semiconductor materials, configured in such a way that it will transport heat to or away from a test specimen dependent on the direction of electric current applied to the device.
