Volume 21, Issue 5 (September 1993)
Analysis of Jet Fuel Thermal Oxidation Deposits by Spectral Fluorometric Technique
The Jet Fuel Thermal Oxidation Test (JFTOT) is a widely used ASTM test procedure that evaluates the thermal stability of a fuel. It is evidenced by the fuel's resistance to undergo any chemical changes during increased thermal oxidative stress, until such time that a thermal breakpoint temperature is reached. A characteristic trace of the fuel is then deposited onto an aluminum test coupon and the fuel is rated on a pass/fail books relative to industry standards. Current rating systems approved by the industry for evaluating these tube deposit formations often fail to generate repeatable rating results. The required visual inspection of these deposit areas produces considerable uncertainty among many reviewers (due to a host of uncontrolled variables within the human observer). This paper will focus on the needs of the industry for an improved method of evaluating jet fuel thermal oxidation deposits using laser-induced spectral flourometry (SF). A novel device for reading these tube deposit areas from the cylindrical surface of an aluminum test coupon will be described as well. The overall technique yields an array of objective criteria for the evaluation of heater tube deposit areas and shows great potential for the identification of individual jet fuels on the basis of their fluorescent profiles.