8. Calculations and Report
8.1 Calculate maximum foam height, F m , as follows:
Fm = M - I
where:
I = initial height (7.10), and
M = maximum total height at zero time (7.12).
8.2 Time to Defoam to 10 mm (7.13) - Record the time to defoam to 10 mm of net foam to the nearest 0.5 min if foam subsides within the 5-min test time. Otherwise record "5 +".
8.3 Calculate residual foam after 5 min, Fr, as follows:
Fr = R - I
where:
R = residual total height (7.14)
NOTE 7 - A suitable report form is described in Fig. 2.
9. Precision and Bias
9.1 The precision of the method as determined by the statistical examination of interlaboratory test results is as follows:
9.1.1 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:
9.1.2 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, exceed the following values only in one case in twenty:
9.2 Bias - Since there is no accepted reference suitable for determining the bias for the procedure in this test method, no statement on bias is being made.
NOTE 8 - Time to Defoam data are not usable to determine precision by the prescribed method as most data read either less than 0.5 min, or 5 + min. See Fig. 3 for sample data.
NOTE 9 - Referee Work - No more than three replicate tests will normally be required.
10. Keywords
10.1 aqueous media; blender test; foam; high shear; water based metal working coolant