ASTM D1837-17

4.1 Volatility, expressed in terms of the 95 % evaporated temperature of the product, is a measure of the amount of least volatile components present in the product. Coupled with a vapor pressure limit, it serves to ensure essentially single-component products in the cases of commercial grades of propane and butane. When volatility is coupled with a vapor pressure limit which has been related to density, as in the case of the commercial PB-mixture, the combination serves to assure essentially two component mixtures for such fuels. When coupled with a proper vapor pressure limit, this measurement serves to assure that special-duty propane products will be composed chiefly of propane and propylene and that propane will be the major constituent.

1.1 This test method is a measure of the relative purity of the various types of liquefied petroleum (LP) gases and helps to ensure suitable volatility performance. The test results, when properly related to vapor pressure and density of the product, can be used to indicate the presence of butane and heavier components in propane-type LP-gas, and pentane and heavier components in propane-butane and butane-type fuels. The presence of hydrocarbon compounds less volatile than those of which the LP-gas is primarily composed is indicated by an increase in the 95 % evaporated temperature.

1.2 When the type and concentration of higher boiling components is required, chromatographic analysis should be used.

1.3 The values stated in SI units are to be regarded as the standard.

1.4 1.4.1 Note that thallium in a mercury-thallium thermometer is also a hazardous material.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.