ASTM D3241 - IP 323 Standard Specifications for Aviation Turbine Fuel ASTM D1655 - D7566 - Def Stan 91-91




The ASTM D3241 / IP 323 Thermal Stability test is one of the most important tests for jet fuel quality.
This test method is inherently limited due to the subjectivity in the color standard for tube deposit rating.
Recently advanced testing metrics (called metrological method) for quantifying the thermal stability characteristics of jet fuels was declared the referee technique by jet fuel specification bodies.
This new approach highlighted the weaknesses of the existing thermal jet fuel oxidation test rigs. By precisely mapping the thermal oxidation deposit on the surface of the aluminum tube, it became possible to identify issues with existing test rigs that were undetectable with the visual (VTR) rating.
Based on these finding, AD Systems developed a new jet fuel thermal oxidation test rig (TO10) that ensures perfect fuel preparation, perfect fuel flow control, a perfect heater tube temperature profile and perfect thermal deposit quantification with the Deposit Rater ? DR10.

Significance and Use
The Jet Fuel Thermal Oxidation is a test method for measuring the high temperature stability of gas turbine fuels.
This test method is recreating the thermal stresses experienced by aviation fuels in jet engines.
Thermal stability measurements are related to the amount of deposit formed on hot surfaces of the engines in contact with the fuel. The break point is defined as the maximum temperature at which the deposit of insoluble particles issued from jet fuels oxygenated is acceptable.
The test is generally performed at 260°C.At the end of the test the deposit on aluminum heater tube is rated.
The test is "failed" if the thickness of the deposit is over 85nm.
The breakpoint is defined as maximum temperature with 5°C step at which the test is passing, meaning thickness of the deposit below 85nm.
The fuel is pumped through an aluminum heater tube maintained at constant temperature like 260°C , after which it enters a stainless steel filter where fuel degradation products may become deposited.
The essential data derived is the amount of deposit on the aluminum heater tube whose thickness is then measured by interferometric method (for instance) or visually rated. The second essential data is the increasing of differential pressure around particle filter trap indicating the presence of oxygenated particles in the fuel.

The thermal Oxidation test with TO10 is very simple.
Install the heater tube section without any tool, prepare the 600ml filtered sample in the left beaker and select the test method.
The TO10 will automatically Oxygenate the sample and circulate the fuel around the heater tube at the programmed temperature and duration. At the end of the test when the heater tube is cooled down, the operator will remove it from the test section and install it on the optional deposit rater unit DR10 to measure deposit thickness.
The tube rating will be automatically transmitted to the TO10 test rig, and can also be printed or saved on USB key and also transmitted to a LAN if it is connected.

Break Point Assistance
When searching fora jet fuel Thermal Oxidation Break Point the analyzer will automatically propose the next temperature test to reduce the number of necessary runs.
The algorithm embedded in the TO10 has been developed by IFPen (Institut Français du Pétrole et des Energies Nouvelles) and can reduce by 25% to50% the number of tests necessary for this determination.
Every break point determination will be saved in the database as a unique test to simplify data management.
A curve will also indicate the thickness deposit tendency depending on test temperature.

Feaures and benefit
- Quick, and objective rating using DR10 tube rater
The TO10 is an automated instrument that strictly follows the test method with an improved precision.
It eliminates the subjectivity inherent to the visual rating when using the optional DR10 tube rater.
The Break Point Assist mode reduce the number of tests necessary to determine the Break Point. No technical knowledge is necessary, the TO10 automatically defines the best temperature of the next test depending on previous results.
- Test preparation
To install and remove the heater tubes, no tools necessary. Every part is easily installed by tightening with fingers. A tube gauge is provided to simplify the heater tube installation without necessary adjustment.
- Increases safety
The TO10totally eliminates all safety risks, the test section is protected by a transparent window and is illuminated by red light indicating high temperature. The operator is informed when the test section is cooled.
- Reduces labor
The TO10 is a ?Set it and Forget it? instrument. Once the test is launched, the TO10 is automatically managing the test, including the test section chilling.
When the TO10 is used with the optional DR10 tube rater, the tube rating is automatically recorded in the TO10 DataBase
- Mimics strictly the method with improved precision
The TO10 is an automated instrument. It uses exactly the same test condition described in the method, respecting aeration condition as well as the sample circulation. Every parameter is controlled better than requested, even some additional parameters are controlled including bottom bus bar and air flow during aeration phase.
- Quality Procedure features
The TO10features a built-in result data base. All details related to each test result are memorized. In addition, all information related to the instrument calibration is memorized to ensure a perfect traceability.