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.

The Jet Fuel Thermal Oxidation Tester (JFTOT) is used by the Air Force to determine the thermal stability of JP-4 and JPTS type fuels. A device called the Tube Deposit Rater (TDR) has been proposed as a means of evaluating the deposits formed on JFTOT tubes. (Author) Concern has existed about the need to account for the pretest condition of the test tubes. The effect of pretest ratings is discussed in the report and a method is proposed for improving results by accounting for the pretest condition of the tubes. (Author).

Thermal oxidation products from jet fuels will be formed in the presence of fuel and oxygen at elevated temperatures. Development of fuels that will not form solid residues depends on the development of a method to analyze the rate of oxidation of fuels. Gravimetric determination of fuel residues was imprecise and time consuming. Gas Chromatography - Mass Spectrometry of oxidation products yields a great deal of fundamental information but is too specific to be used as a rapid method for determining the rate of oxidation. Fourier Transform Infrared Spectrometry is non-specific and gives integrated signals for classes of oxidation products that will give rapid analytical results for rates of oxidation as well as the ability to study the effectiveness of chemical additives.

Thermal oxidation products from jet fuels will be formed in the presence of fuel and oxygen at elevated temperatures. Development of fuels that will not form solid residues depends on the development of a method to analyze the rate of oxidation of fuels. Gravimetric determination of fuel residues was imprecise and time consuming. Gas Chromatography - Mass Spectrometry (GC-MS) of oxidation products yields a great deal of fundamental information but is too specific to be used as a rapid method for determining the rate of oxidation. Fourier Transform Infrared (FTIR) Spectrometry is non-specific and gives integrated signals for classes of oxidation products that will give rapid analytical results for rates of oxidation as well as the ability to study the effectiveness of chemical additives.