Understanding the Effectiveness of Diesel Fuel Flow Improvers

A new laboratory test, the Diesel Fuel Cold Filterability Test (DIFCOFIT), has been developed to predict fuel filter plugging by diesel fuels containing flow improver additives, and to understand how flow improvers interact with diesel fuels to affect low-temperature operation of diesel vehicles. In the test, a sample of diesel fuel is cooled at a rate of 2°C/h and filtered at 1°C decrements below its cloud point through 37, 125, and 420 μm screens to determine filter plugging temperatures. Flow improver effectiveness was found to depend on additive concentration as well as fuel n-paraffin concentration and distribution. Mechanisms are proposed to explain the effectiveness of flow improvers on the basis of these factors.