Patent ID: 8192510

Claim:
A method of blending butane into a gasoline supply that also is mixed with a fixed ratio of ethanol, in an amount that does not cause the gasoline/ethanol mix to pass one or more fixed volatility limits selected from vapor pressure, vapor liquid ratio, T(10) and T(50), wherein the gasoline supply varies over time in terms of content and volatility potential, comprising: a. providing (i) a supply of gasoline, (ii) an ethanol standard, and (iii) a supply of butane; b. analyzing the volatility of a sample formed by mixing the gasoline and ethanol standard; c. calculating from the volatility a ratio of butane that can be blended into the sample without causing the sample to pass the one or more fixed volatility limits; and d. blending butane from the butane supply with gasoline from the gasoline supply at or below the ratio calculated in step (c).