Simple Analytical Techniques to Determine the Disperant Capacity and Metal Deactivator Additive Concentration of JP-8+100 and Other Jet Fuels

Abstract

The US Air Force is developing an additive package to improve the thermal stability of JP-8 fuels by 100°F. Consequently, JP-8 fuels containing the developed additive package are referred to as JP-8+100 fuels. Field tests of the JP-8+100 fuels have shown that the additive package greatly reduces maintenance cost and labor in comparison to JP-8 fuels by minimizing fuel system malfunctions caused by fuel deposition, e.g., fuel control changeouts, combustor damage, etc. The developed additive package contains three components: antioxidant, dispersant/detergent, and metal deactivator. This paper presents simple analytical techniques that can be performed on-site or in the laboratory to determine the dispersant capacity and metal deactivator additive concentrations of JP-8+100 fuels. Since several dispersant/detergent candidates are being evaluated for use in the JP-8+100 additive package, the analytical techniques were developed to measure the dispersant capacity of the additive package instead of the concentration of one particular dispersant/detergent. The dispersant capacity test measures the ability of a fuel sample to suspend a metal oxide powder/water/isopropanol mixture. The dispersant capacity test can be used to identify jet fuels which contain the JP-8+100 additive package and to rate the dispersant capacity of a JP-8+100 fuel. In contrast to the dispersant capacity test, the metal deactivator additive (MDA) tests were designed to determine the concentration of N,N′-disalicylidene-1,2-propanediamine which is the primary MDA used in jet fuels. The MDA tests use fuel soluble compounds or aqueous extraction to chemically react MDA to form colored species. The color of the MDA compound is measured visually for qualitative determinations or spectrometrically for quantitative determinations. Combination of the different MDA tests allows MDA to be detected down to 0.1 ppm regardless of fuel color, age, or type.