9. Calculation and Report
9.1 Calculate the lithium content of the grease as follows:
Lithium, mass % = X/100 W
where:
X = lithium content of the water extract, mg/L lithium (see 8.7), and
W = mass of the grease taken, g.
Modify the formula if further dilution of the water extract was necessary, for example, if further dilution of 50 mL to 200 mL was made, then:
Lithium, mass % = (X)(200)/(100 W)(50)
9.2 Report the result as lithium content.
9.3 Calculate the sodium content of the grease as follows:
Sodium, mass % = Y/100 W
where:
Y = sodium content of the water extract in mg/L sodium (see 8.7), and
W = mass of the grease taken, g.
Modify the formula if further dilution of the water extract was necessary as in 9.1.
9.4 Report the result as sodium content.
10. Precision and Bias
NOTE 2 - The precision data were derived within the IP. The method has not as yet been cooperatively tested by ASTM.
10.1 The precision of this test method as determined by statistical examination of interlaboratory results is as follows:
10.1.1 Lithium:
10.1.1.1 Repeatability - The difference between two test results, obtained by the same operator with the same apparatus under constant operating conditions on identical test material, would in the long run, in the normal and correct operation of the test method, exceed the following values only in one case in twenty:
10.1.1.2 Lithium 0.014(x)(2/5)
10.1.1.3 Sodium 0.029(x)(2/5)
10.1.2 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, in the normal and correct operation of the test method, exceed the following values only in one case in twenty:
10.1.2.1 Lithium 0.075(x)(2/5)
10.1.2.2 Sodium 0.166(x)(2/5) where x is the lower of two values.
NOTE 3 - The applicable range of concentrations are 0 to 0.4 % mass/mass lithium and 0 to 8 % mass/mass sodium.
NOTE 4 - These precision values have been obtained by statistical examination of interlaboratory test results by the Institute of Petroleum and were first published in 1966. They were obtained from the test results from nine laboratories using the following instruments:
10.2 Bias - The bias of this test method cannot be determined because no suitable reference material is available.
NOTE 5 - The values of these precision estimates for selected values of x are set out in the Table 1.
11. Keywords
11.1 flame photometer; lithium content; lubricating grease; sodium content; thickener