ASTM D1837 Standard Test Method for Volatility of Liquefied Petroleum (LP) Gases
3. Summary of Test Method
3.1 Refrigerate the sample by means of a cooling coil and collect 100 mL of liquid in a weathering tube. Allow to evaporate ("weather") at ambient pressure under specified conditions that approximate a single plate distillation. Correct the observed temperature, when 5 mL of liquid test portion remains, for barometric pressure and thermometer ice point error, and report as the 95 % evaporation temperature.
4. Significance and Use
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.
