Originally Posted By: demarpaint
Originally Posted By: Gokhan
Claimed NOACK is 12.6%. NOACK tests are known to be highly erroneous; therefore, PQIA might have got it wrong in only one try. The only way to make sure is to repeat the test at least ten times or so and take the average.
All the oils PQIA tests for NOACK are one offs and therefore their results are wrong across the board? For the record I'm not trying to start a fight, just asking a question. I would have thought they had that figured out by now.
Here are the data from ASTM D 5800-08 for Noack. There are three procedures.
Quote:
14.1.1 Repeatability—A quantitative measurement of precision associated with single results obtained by the same operator with the same equipment in the same laboratory within a short interval of time. In the normal and correct operation of the test method, the following values were exceeded in only one case in twenty.
Repeatability = 5.8 % X average M/M evaporation loss (2)
14.1.2 Reproducibility—A quantitative measure of preci- sion with single results obtained in different laboratories on identical test material. In the normal and correct operation of the test, the following values were exceeded in only one case in twenty.
Reproducibility 5 18.3 % X average M/M evaporation loss (3)
Quote:
24.3.1 Repeatability—The difference between two tests re- sults obtained by same operator with the same apparatus under constant operating conditions on identical test materials would, in the long run, exceed the following value in only one case in twenty.
Repeatability = 0.095X0.5 (10)
where:
X = average of the two determinations under consideration.
24.3.2 Reproducibility—The difference between two single and independent results obtained by different operators work- ing in different laboratories on identical test materials would, in the long run, exceed the following value in only one case in twenty.
Reproducibility = 0.26X0.5 (11)
where:
X = average of the two determinations under consideration.
Quote:
33.2 Repeatability—The difference between successive re- sults obtained by the same operator with the same apparatus under constant operating conditions on identical test materials would, in the long run, in the normal and correct operation of the test method, exceed the following value in only one case in twenty:
Repeatability, % evaporation loss = .81 (12)
33.3 Reproducibility—The difference between two single and independent results obtained by different operators work- ing in different laboratories on identical test materials would, in the long run, in the normal and correct operation of the test method, exceed the following value in only one case in twenty:
Reproducibility, % evaporation loss = 1.62 (13)
I'm not familiar with the reporting convention used in procedures B and C, so I'll leave that to the statisticians in the group to interpret.
Assuming procedure A, 12.6 and 14.2 are within the reproducibility of the method.
Full ASTM Method here:
http://www.pentasflora.com/wp-content/uploads/2014/02/D5800-NOACK-Volatility.pdf
Ed