ASTM D7109 Standard Test Method for Shear Stability of Polymer Containing Fluids Using a European Diesel Injector Apparatus at 30 and 90 Cycles
13. Report
13.1 Report the following information:
13.1.1 The calibration pressure, in MPa,
13.1.2 Kinematic viscosity of the unsheared oil at 100°C,
13.1.3 Kinematic viscosity of the 30-cycle sheared oil at 100°C,
13.1.4 Kinematic viscosity of the 90-cycle sheared oil at 100°C,
13.1.5 Percent viscosity loss of the 30-cycle sheared oil (PVL30) as calculated in 12.1, and
13.1.6 Percent viscosity loss of the 90-cycle sheared oil (PVL90) as calculated in 12.1.
14. Precision and Bias
14.1 The precision of this test method as determined by the statistical examination of interlaboratory test results is as follows:
14.1.1 Repeatability - The difference between successive test results, obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, and in the normal and correct operation of the test method, exceed the following values only in one case in twenty:
PVL30: 1.1 %
PVL90: 1.2 %
14.1.2 Reproducibility - The difference between two single and independent results, obtained by different operators working in different laboratories on identical test material would, in the long run, and in the normal and correct operation of the test method, exceed the following values only in one case in twenty:
PVL30: 1.9 %
PVL90: 2.0 %
NOTE 21 - The indicated repeatability and reproducibility values for PVL 30 and PVL 90 represent the arithmetic difference between the reported percent kinematic viscosity loss values for the two results being compared. For example, 10% viscosity loss and 12% viscosity loss differ by 2%.
14.2 Bias - All test results are relative to those of the calibration fluid. Therefore, no estimate of bias can be justified.
14.3 The precision and bias statements were determined through statistical examination of 171 results from nine laboratories on ten oils. Eight of the oils were SAE 15W-40 grade, and two were SAE 10W-30 grade. The oils contained at least eight different viscosity modifiers of four different chemistries, ranging in Shear Stability Index from 15 to 37, from at least five different suppliers.
15. Keywords
15.1 diesel injector apparatus; mechanical shear stability; polymer containing fluid; viscosity loss
