RFG that is designated as VOC controlled by the refiner must use the summer model and must comply with the RVP standard for the appropriate VOC control region. RFG that is designated as non-VOC controlled by the refiner must use the winter model.

Refiners may not designate RFG as VOC controlled unless it meets the federal RVP standard for VOC controlled RFG for the appropriate VOC control region. Consequently, California RFG produced to 7.8 psi for use outside the federal VOC control period (i.e., before May 1 and after September 15) would use the winter model. (5/9/95)

This question and answer was posted at Consolidated List of Reformulated Gasoline and Anti-Dumping Questions and Answers: July 1, 1994 through November 10, 1997 (PDF)(333 pp, 18.17 MB, EPA420-R-03-009, July 2003, About PDF)