Evaluation of Several Methods to Measure Volatility of Motor Fuels

摘要

The U.S. Environmental Protection Agency is proposing regulations to reduce the amount of hydrocarbons released to the atmosphere due to the evaporation of automotive fuels. The new regulations may define upper volatility limits for these fuels based on seasonal climatic patterns. Volatility of gasoline fuels is typically quantified by measurement of Reid vapor pressure (RVP). Although an established procedure exists for the assessment of the parameter (ASTM S 323), there is question as to the accuracy of the procedure when evaluating fuels with water-interactive constituents, e.g., alcohols and ethers. ASTM P 176 is a procedure which has been proposed as its replacement. It addresses the problem of water and is known as the 'dry' version of ASTM D 323. The correlation study was designed to evaluate the proposed ASTM P 176 procedure for repeatability and reproducibility. The results of the study will help establish a basis for enforcement tolerance. Also evaluated was the equivalency of results from two commercial instruments versus those obtained by the traditional 'gauges and bath' techniques.