ACIDITY IN AVIATION TURBINE FUEL: D3242
(Equivalent Tests: IP 354 and DIN 51558 T3)
EXPLANATION
Some acids can be present in aviation turbine fuels due either to the acid treatment during the refining process or to naturally occurring organic acids. It's unlikely that significant acid contamination will be present because of many check tests made during the refining process. In any case these trace acid quantities are undesirable because of the possibility of metal corrosion and impairment of water separation characteristics of the fuel.
This test method covers the determination of the acidity in an aviation turbine fuel in the range 0.000 to 0.100 mg KOH / g. It is, however, not suitable for determining significant acid contamination.
TEST SUMMARY
A sample is dissolved in a solvent mixture (toluene plus isopropyl alcohol, and a small amount of water) and under a stream of nitrogen is titrated with standard alcoholic KOH to the color change from orange in acid to green in base via added indicator p-naptholbenzein solution.
TEST PRECISION
The test repeatability is 0.0132 a and test reproducibility is 0.0406 a where a is the acid number. These data are based on the manual burets only; precision for using automated burets is not known. This test method has no bias.
