The Cold Soak Filtration Test (CSFT) is intended to assess the presence of impurities that may precipitate from fuel above the cloud point and cause filter plugging. The test is designed to accelerate precipitate formation. Short filtration times indicate the absence of substances that are likely to cause filter pugging at temperatures above the cloud point. Generally, B100 with low CSFT results and blends made from the B100 will perform well down to the cloud point. CSFT is performed in accordance with ASTM D7501.
ASTM D6751 Requirement: a maximum filtration time of 360 seconds. There is a maximum filtration time of 200 seconds to qualify as a Grade No. 1B biodiesel (a maximum Monoglyceride content of 0.40% mass as well as passing results for the remaining ASTM D6751 analyses is required for a No. 1B designation).