13.1 Correction for barometric pressure. Observe and record the ambient barometric pressure at the time and place of the test. When the pressure differs from 101.3 kPa (760 mm Hg), correct the flash point as follows:
Corrected flash point = C + 0.25 (101.3 - p)
Corrected flash point = F + 0.06 (760 - P)
Corrected flash point = C + 0.033 (760 - P)
where:
C = observed flash point, °C,
F = observed flash point, °F,
p = ambient barometric pressure, kPa, and
P = ambient barometric pressure, mm Hg.
13.2 The barometric pressure used in this calculation shall be the ambient pressure for the laboratory at the time of test. Many aneroid barometers, such as those used at weather stations and airports, are precorrected to give sea level readings; these shall not be used.
13.3 Report the corrected flash point to the nearest 0.5°C (or 1°F).
14. Precision and Bias
14.1 Precision - The following criteria shall be used for judging the acceptability of results (95 % probability):
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, in the normal and correct operation of the test method, exceed the following values only in one case in twenty:
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, in the normal and correct operation of the test method, exceed the following values only in one case in twenty:
14.2 Bias - The procedure in Test Method D 56 for measuring flash point has no bias since the tag flash point can be defined only in terms of this test method. The current interlaboratory tests confirm that there is no relative bias between manual and automated procedures. In any case of dispute the flash point as determined by the manual procedure shall be considered the referee test.
NOTE 7 - Mixtures such as, but not limited to, those that are chlorinated or include water may cause significant differences in the results obtained by manual and automatic instruments. For these mixtures, the precision statement may not apply.
NOTE 8 - The precision data were developed in a 1991 cooperative test program6 using eight (8) samples. Twelve (12) laboratories participated with the manual apparatus and seventeen (17) laboratories participated with the automatic equipment. Information on the type of samples and their average flashpoints are in the research report.
15. Keywords
15.1 combustible; fire risk; flammable; flash point; tag closed cup