ASTM D2532 Test Method for Viscosity and Viscosity Change After Standing at Low Temperature of Aircraft Turbine Lubricants
9. Precision and Bias
9.1 Precision - The following criteria should be used for judging the acceptability of results at a 95 % confidence level.
9.1.1 Repeatability - The difference between successive test results obtained by 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 after the 35-min period the values shown on the repeatability curve in Fig. 1 only in one case in twenty. Differences greater than this should be considered suspect.
9.1.2 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 after the 35-min period the values shown on the reproducibility curve in Fig. 1 only in one case in twenty. Differences greater than this should be considered suspect.
9.1.3 The precision of kinematic viscosity determinations after standing times in excess of 35 min has not been calculated because it has been found that certain oils, while held in storage at -53.9°C (-65°F), develop characteristics that cause wide variations in observed kinematic viscosities.
9.2 Bias - Since there is no accepted reference material suitable for determining the bias for this test method, no statement on bias is being made.
10. Keywords
10.1 aircraft turbine lubricants; kinematic viscosity; viscosity
