ASTM D8171-18

1.1.1 Test Method A-Gas Pycnometry-This is the more accurate method of density measurement and is preferred in cases in which specimen conditioning (oven drying) can be applied or outgassing effects can be mitigated by purge settings. The level of accuracy for the test methods can be assessed from the precision and bias tables. Outgassing effects can be assessed by performing a purge cycle, pressurization, and pressure stability check on the sample. If the pressure increases in an isolated sample chamber, outgassing may affect the accuracy of results. Oven dry specimens below 55 ºC to equilibrium with a 0 % relative humidity (RH) environment or use longer purge methods, or both, to eliminate outgassing effects.

1.1.2 Test Method B-Buoyancy (Archimedes) Method-This is acceptable as an alternative to Test Method A in applications in which less accurate results are sufficient, as represented in the precision and bias tables. Test Method B is preferred in cases in which outgassing effects in Test Method A cannot be addressed by oven drying or purge settings and prevent Test Method A from producing valid results.