ASTM D2158 Standard Test Method for Residues in Liquefied Petroleum (LP) Gases
4. Summary of Test Method
4.1 A 100-mL sample of liquefied petroleum gas is weathered in a 100-mL centrifuge tube. The volume of residue remaining after heating the tube to 38°C is measured and recorded.
4.2 To dissolve any residue, 10 mL of solvent is added to the centrifuge tube. Small, measured volumes of solvent-residue mixture are deposited on an absorbent paper in a specified manner. The appearance of the absorbent paper to which the residue solution has been added in measured increments is observed and recorded.
5. Significance and Use
5.1 Control over the residue content (required by Specification D1835) is of considerable importance in end-use applications of LPG. In liquid feed systems residues can lead to troublesome deposits and, in vapor withdrawal systems, residues that are carried over can foul regulating equipment. Those that remain will accumulate, can be corrosive, and will contaminate following product. Water, particularly if alkaline, can cause failure of regulating equipment and corrosion of metals.
6. Interferences
6.1 Solid contaminants such as rust, scale or dirt can interfere with this test method, which is not intended for representative measurement of solid, undissolved contaminants.
