WATER UNDISSOLVED IN AVIATION TURBINE FUELS: D3240
EXPLANATION
Undissolved (free) water in aviation fuel can encourage the growth of microorganisms and subsequent corrosion in the tanks of aircraft and can also lead to icing of filters in the fuel system. The usual range of the test reading covers from 1 to 60 ppm of free water. This test method does not detect dissolved water, and thus test results for comparable fuel streams can vary with fuel temperature and the degree of water solubility in the fuel.
TEST SUMMARY
A measured sample of fuel is passed through a uranine dye-treated filter pad. Undissolved water in the fuel will react with the uranine dye. When the pad is subsequently illuminated by ultraviolet light, the dye previously contacted by water will fluoresce a bright yellow with the brightness increasing for increasing amounts of free water in the fuel. The UV light-illuminated pad is compared to a known standard using a photocell comparator, and the free water in the fuel is read out in ppm by volume. By varying the sample size, the range of the test method can be increased.
TEST PRECISION
Repeatability: 0.32X
Reproducibility: 0.47X
Where X is the average of two results in ppm by volume over the range from 1 through 60 ppm/v.
Bias has not been determined.
