ASTM D1837 Standard Test Method for Volatility of Liquefied Petroleum (LP) Gases
7. Interpretation of Results
7.1 Correct the thermometer at the 95 % boiling point (5 % residue) for the thermometer error (6.7).
7.2 Correct the observed temperature for the thermometer error from the observed atmospheric pressure in kPa (millimetres of mercury) to a base barometric pressure of 101 kPa (760 mm).
7.3 In the weathering test for propane, add 0.3°C (0.6°F) to the corrected temperature for each 1.3 kPa (10 mm Hg) that the test is conducted below 101 kPa (760 mm) pressure, or subtract 0.3°C (0.6°F) from the observed temperature for each 1.3 kPa (10 mm Hg) that the test is conducted above 101 kPa (760 mm).
7.4 In the weathering test for butane and propane-butane mixtures, add 0.4°C (0.7°F) to the corrected temperature for each 1.3 kPa (10 mm Hg) that the test is conducted below 101 kPa (760 mm) pressure, or subtract 0.4°C (0.7°F) from the observed temperature for each 1.3 kPa (10 mm Hg) that the test is conducted above 101 kPa (760 mm).
8. Precision and Bias
8.1 The following criteria should be used for judging the acceptability of results (95 % confidence):
8.1.1 Repeatability - The difference between two test results obtained by the same operator with the same apparatus under constant operating conditions on identical test materials would in the normal and correct operation of the test method, exceed the following value only in one case in twenty:
0.6°C (1.0°F)
8.1.2 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 value only in one case in twenty:
1.0°C (1.7°F) for butane and propane-butane mixtures, and 1.3°C (2.3°F) for propane
8.2 Bias - The procedure in this test method for measuring volatility of LP-gases has no bias because the volatility is defined only in terms of this test method.
9. Keywords
9.1 butane; liquefied petroleum (LP) gases; LPG; propane; volatility
