This test method described in this document covers a procedure to speciate that is, to determine the amounts of each different fuel constituent that permeates across sheets, films or slabs of plastic materials. One side of the sheet is meant to be in contact with either a liquid test fuel or a saturated test fuel vapor, the other side is meant to be exposed to an environment free of fuel. The test fuel can either be a mixture of a small (usually smaller than ten) number of hydrocarbon, alcohol and ether constituents or it can be a sample of a real automotive fuel, e.g., one that may contain hundreds of different constituents. Furthermore, Appendix A contains guidelines to speciate evaporative emissions from finished fuel system components such as fuel lines, fuel filler pipes, fuel sender units, connectors and valves.
This 2012 version of SAE Vehicle standard SAE J2659 includes some editorial updates of the document released in December 2003. The appendix was updated to include an additional illustration for measuring permeation of tubes. Although this SAE J2659 is not widely applied to fuel system materials, the speciation approach described is helpful for a more complete understanding of material permeation, especially with respect to ethanol fuels.