The presence of acids and/or sulphur-containing compounds in biodiesel can lead to, among other problems, corrosion of nonferrous material such as copper, zinc, brass and bronze in an engine.  The copper strip corrosion test replicates this phenomenon by immersing a polished strip made out of copper in a biodiesel sample to determine its relative degree of corrosivity on nonferrous metal parts.  The copper strip corrosion test can be correlated with the acid number (test method D664) to indicate high levels of sulphur and acids in the test sample.

Significance

ASTM method D130 is the only standard test method available to test copper strip corrosion.  As mentioned, a polished strip of copper is immersed in a sample of biodiesel and heated at 100°C for a period of three hours in a copper strip corrosion bath.  After the allotted time, the strip is removed and compared to a standard ASTM test strip to determine the level of corrosion.