API Publ 4699:2000 pdf download.Strategies for Characterizing Subsurface Releases of Gasoline Containing MTBE
2.2 USE OF OXYGENATES IN GASOLINE
The commercial use of fuel oxygenates in the United States began in 1979 following the phase-out of leaded gasoline. Oxygenates were originally valued for their high octane ratings (MTBE has an octane rating of 110, while ethanol has an octane rating of 112.5), and they were used primarily as octane boosters in premium gasolines. In 1981, the U.S. EPA approved the use of MTBE in gasoline at levels up to 10 percent by volume (California EPA, 1997). MTBE was widely used as an octane booster during the 1980s, commonly at concentrations of about 2 to 9 percent by volume in premium gasoline, and at concentrations of less than 1 percent in regular gasoline (Ellis and Gavas, 1996). Oxygenates were subsequently used at higher concentrations to reduce vehicle emissions and improve air quality. The first oxygenated fuel program was conducted in the Denver area during January and February 1988. The 1990 CAAA established two new fuel programs administered by the U.S. Environmental Protection Agency, that required the use of “federal oxygenated gasoline” or “federal reformulated gasoline.” These two programs greatly expanded the use of oxygenates nationwide. At present, approximately 30 percent of the gasoline sold in the United States contains oxygenates for air quality improvement purposes (U.S. EPA, 1998).Federal oxygenated gasoline has been used in some 40 metropolitan areas throughout the United States, beginning in October 1992. It is primarily intended to reduce carbon monoxide emissions, and its use is mandated only during winter months. Federal oxygenated gasoline normally must contain at least 2.7 percent oxygen by weight, but no particular oxygenate is specified. This oxygen requirement can be met by using 15 percent MTBE by volume, or 7.3 percent ethanol by volume. The oxygen requirement is subject to local modification. In California, for example, federal oxygenated gasoline need only contain 1.8 to 2.2 percent oxygen by weight. In other areas, federal oxygenated gasoline may contain up to 3.5 percent oxygen by weight (U.S. EPA, 1999c).
Federal reformulated gasoline (RFG) has been used in some 28 metropolitan areas throughout the United States, beginning in January 1995. It is primarily intended to reduce ozone production, and its use is required year round. Federal RFG must contain at least 2.0 percent oxygen by weight during the summer ozone season, but no particular oxygenate is specified. This oxygen requirement can be met by using 11 percent MTBE by volume, or 5.4 percent ethanol by volume. In April 1996, the State of California mandated the use of “California Phase 2 Reformulated Gasoline” on a statewide, year-round basis. The prescriptive formula for California RFG calls for 1.8 to 2.2 percent oxygen by weight, but this requirement can be waived if equivalent emissions reductions can be achieved using alternative formulations. Thus, California RFG (unlike federal RFG) may or may not contain oxygenates. However, the use of federal RFG (which must contain oxygenates) is still mandated in those parts of California that are required by the CAA to participate in the federal RFG program.
API Publ 4699:2000 pdf download
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