ASTM D6423 Determination of pHe of Ethanol, Denatured Fuel Ethanol, and Fuel Ethanol (Ed75-Ed85)
11. Precision and Bias
11.1 Precision - The precision of this test method as determined by statistical examination of the interlaboratory test results is as follows:
11.1.1 Repeatability - The difference between successive test results, obtained by the same operator using the same apparatus under constant operating conditions on identical test material, would in the long run, in the normal and correct operation of this test method, exceed 0.29 pHe in only one case in twenty.
11.1.2 Reproducibility - The difference between two single and independent test results, obtained by different operators working in different laboratories on identical test material, would in the long run, in the normal and correct operation of this test method, exceed 0.52 pHe in only one case in twenty.
11.2 Bias - Since there is no material having an accepted reference value for pHe, bias cannot be determined.
12. Keywords
12.1 acid strength; automotive spark ignition engine fuel; corrosion potential; denatured fuel ethanol; ethanol; fuel ethanol; pHe
