Determination of Vicat softening temperature for plastic pipes
ISO 2507-1 (general test method), EN ISO 2507-2, EN ISO 2507-3
When testing pipes, the Vicat softening temperature VST is usually determined in accordance with ISO 2507-1 (general test method), EN ISO 2507-2, EN ISO 2507-3 (as a replacement for EN 727).
Purpose of the test
- This test is concerned with the characterization of a thermoplastic pipe material with regard to its thermal behavior. Accordingly, the test is applied if the eventual use of a pipe is intended for elevated temperatures.
- The VST measurement value does not represent a physical quantity, but serves as a comparative value for testing and classifying materials under the same test conditions.
- The Vicat softening temperature indicates the temperature at which a circular indenter with a cross-section of 1 mm² under a standard load of 10 N or 50 N will penetrate the specimen precisely 1 mm deep. The Vicat softening temperature is defined in ISO 306 and ASTM D1525.
- Classical VST instruments use silicone oil as heat transfer fluid. This is the most cost-effective method, which can be carried out accurately and precisely. In addition, processes have been established that work with air or other media for heat transfer, but often tend to provide less accurate values and greater value variation. ISO 306 offers a reliable method with direct contact heat transfer from the metal surfaces to the specimen. This oil-free method is particularly suitable if odor pollution from heated oil is a problem and the VST test must be carried out on a regular basis.
