Wax Dispersing Filterability Test (WDFT) October 10, 2019 Wax Dispersing Filterability Test (WDFT) NEW Wax Dispersancy Test Developed Cold flow properties of diesel fuel have been analyzed with a battery of standard tests for years. When diesel fuel temperature reaches or falls below the fuel’s cloud point, paraffin in the fuel begins to change to solid wax crystals. These crystalline wax structures agglomerate together and become heavier and fall to the bottom of the fuel tank where fuel draw lines are located. When enough wax accumulates in the bottom of the diesel fuel tank, the draw line pulls pure wax into the fuel filters causing restriction and plugging. Cloud Point (CP) testing determines at what temperature wax crystals begin to form and the fuel becomes visually cloudy. Diesel fuel additive producers use these tests to determine if their additives are working. Tests are run on diesel fuel that has been treated with additives and compared against a baseline of the untreated diesel fuels. One diesel fuel additive blender asked if there were any other tests that would verify that their additives were indeed working to prevent settling of the paraffin wax crystals. They wanted to verify if their additives would continue to work over time to prevent wax settling under extreme conditions. The Wax Dispersing Filterability Test (WDFT) was developed specifically to meet this need. The Wax Dispersing Filterability Test (WDFT) is a new laboratory test that is used to determine if wax crystals are being suspended evenly throughout a sample by wax dispersing additives. The test begins with a 400ml sample of diesel fuel. The 400ml sample is placed in a freezer that is set at a temperature of 10 degrees F below the untreated diesel fuel’s original cloud point. The sample remains in the freezer for a minimum of 24 hours. (The test sample may remain in the freezer for an extended period of time to demonstrate the effects of wax precipitation or suspension over time.) After 24 hours, and while the sample remains in the freezer, first 100ml of diesel fuel is siphoned from the TOP of the sample and placed in a separate sample container. A second 100ml sample is also siphoned from the BOTTOM of the sample and placed in a second container. After the 100ml samples warm to room temperature, a cloud point test is run on each 100ml sample. The result of these cloud point tests from the TOP and BOTTOM sample are compared. Results with similar cloud points would show that the wax is being suspended and the additive performed to expectations. Differences in the top and bottom cloud point results of no more than 1 to 2 degrees is deemed to PASS (acceptable.) Back To News