ASTM D1740 Test Method for Luminometer Numbers of Aviation Turbine Fuels
4. Summary of Test Method
4.1 The luminometer number of a fuel is determined by burning the fuel in the ASTM-CRC Luminometer lamp and obtaining a curve of flame radiation, as measured by an optical filter and photo cell unit against the temperature rise across the burner measured by a thermocouple placed just above the flame. This temperature rise is compared with that obtained on a pair of reference fuels at a constant radiation level. To ensure that the constant rating level is the same in all units, it is defined as the smoke point of tetralin. Luminometer number is calculated from the difference in temperature rise between the test fuel and the temperature rise for tetralin divided by the difference in temperature rise for isooctane and tetralin.
5. Significance and Use
5.1 This test method provides an indication of the relative radiation emitted by the combustion products of gas turbine fuels from a diffusion flame. The radiation level, expressed as luminometer number, is related to the hydrocarbon type composition of such fuels. A high luminometer number indicates a fuel of low radiation characteristics.
5.2 The luminometer number (and the smoke point with which it can be correlated) is qualitatively related to the potential radiant heat transfer from the combustion products of the fuel. Because radiant heat transfer exerts a strong influence on the metal temperature of combustor liners and other hot section parts of gas turbines, the luminometer number provides a basis for correlation of fuel characteristics with the life of these components.
