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Calculation Routines Supporting the use of Diesel Fuel Cold Flow Improvers
CFPP Procedure ASTM D6371
The test tube of fuel is placed in a cold cell at –34°C
As the fuel cools, at each degree drop, the fuel is pulled
through a 45 micron mesh.
The CFPP result is the temperature at which the fuel takes more than one minute to filter.
The UK winter specification is –15°C for Diesel and –12°C for Gas Oil from cloud points of –5 and –2°C.
Central Europe generally blends Diesel to -20 and in Germany –22 °C CFPP from a cloud point of –7°C during the winter season.
The gap between the cloud point and CFPP specification is a significant factor in additive selection and blend formulation.
The quoted Reproducibility (R) is 4.0 and the Repeatability (r) 1.76 for the CFPP test method.
The Excel spreadsheet, AccuracyCFPP.xlsm provides assistance in setting blending targets to take into account the blending process accuracy. A blender should be inside a standard deviation of 1.0 (repeatability 2.8), batch on batch to the same specification. If the variability increases, this may be due to several reasons as follows:-