Accelerated Stability Test Techniques for Middle Distillate Fuels

Abstract

Improved test techniques are needed for evaluating the inherent stability of middle distillate fuels both in surveillance and in procurement activities. A project was initiated to define and evaluate the contributing conditions leading to the formation of deleterious products in accelerated aging tests of middle distillate fuels and to relate these results to an experimental definition of more repeatable/reliable middle distillate fuel stability test technique(s). A literature search was conducted to provide a list of stability test techniques and their interpretations which could be used in a correlative middle distillate fuel stability test program. For this program, seven accelerated stability tests were chosen and evaluated using a set of six test fuels. The test techniques were selected to represent a wide variety of test conditions, including temperature, aging time, and oxygen availability. These six test fuels were purposely chosen to represent a wider range of stabilities than would necessarily be commonly available for procurement. The fuel properties generally measured included both adherent and suspended particulates, steam jet gum, color, and light absorbance at 540 nm. Accelerated stability test results were then related to test results obtained at a storage temperature of 43.3°C, which has generally been regarded as showing good correlation with long-term ambient storage.