California's Phase 2 Reformulated Gasoline (CaRFG2) and Phase 3 Reformulated Gasoline (CaRFG3) regulations require refiners to produce gasoline that meets eight specifications to reduce air pollution from the gasoline used in motor vehicles. One of the eight specifications is a standard for Reid Vapor Pressure (RVP) which is designed to reduce evaporative emissions during the summer months when ambient temperatures are their highest. RVP is measured in pounds per square inch (psi). The lower the psi in gasoline, the less evaporative emissions that generally will occur.
In California, the RVP standards were 9.0 psi until the CaRFG1 regulations were implemented in 1992, which lowered the RVP standard to 7.8 psi.
In 1996, with the implementation of the CaRFG2 regulations, the RVP standard was reduced to a flat limit of 7.0 psi.
In 2004, the CaRFG3 regulations are implemented with a RVP flat limit of 6.9 psi when the evaporative emissions model element of the Predictive Model is used and a cap limit of 7.2 psi.
In 2007, amendments to the CaRFG3 regulations set the RVP flat limit to 7.0 psi for oxygenated fuels and a flat limit RVP of 6.9 psi for non-oxygenated fuels.