Frequent Questions

In general, how are the properties determined for blendstocks that fall outside the scope of the regulatory methods?

Some gasoline blendstocks have properties that cause them to fall outside the scope of the regulatory methods. If properties need to be obtained for these blendstocks, they must be determined by a different route, that being an interpolation based on the measured properties of the gasoline before and after the blendstock is added. For example, to determine the RVP of a blendstock, an appropriate equation would be:

7.60(100,000) + r(5,000) = 7.30(105,000) (I)

760,000 + r(5,000) = 766,500 (II)

r(5,000) = 6,500 (III)

r = 1.30 (IV)

In this example, where the initial fuel sample was 100,000 barrels with an RVP of 7.60, the blendstock volume was 5,000 barrels, and the RVP of the final blend was 7.30, the calculated RVP of the blendstock would be 1.30.(7/1/94)

This question and answer is posted at http://www.epa.gov/otaq/regs/fuels/rfg/qa/420r03009.pdf. The original was posted in the Q&A posted on 11/10/97 which can found at http://www.epa.gov/otaq/rfg_qa.htm" See Question ID 3857 for RFG (Taken from the first question on http://www.epa.gov/otaq/regs/fuels/rfg/qa/420r03009.pdf )

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