The Separation Test
By Rick Da Tech
This test is used to determine when to stop water washing your biodiesel. It works on the basic principle that we have removed enough impurities when the suspended water drops quickly to the bottom without forming an emulsion. The idea is we are mimicing what happens in a fuel tank. If we get water in the tank, and we have not washed enough, it will create an emulsion that can plug filters and destroy your IP. If it is washed enough, then any "suspended" water will be rejected by the biodiesel. Suspended water is water in small droplets that cause the biodiesel to be hazy or turbid.
Scoop out about 50ml of wet biodiesel from your wash tank. I like to take the sample while actively washing. It will be a hazy orange juice looking sample. Place your sample in a warm place like on top of a water heater. Time how long it takes for the biodiesel to become clear or translucent. If it takes longer than 10 minutes, then there are still needs more washing.