Anton Paar has published an Application Note on the use of its Callisto 100 Cold Filter Plugging Point Tester in forecasting the lowest temperature at which a fuel will freely flow through filters in a diesel engine system.
The Cold Filter Plugging Point method is used to describe the procedures for determining low-temperature operability in diesel fuel, biodiesel, blends and gas oils. All diesel fuels contain wax. At some points wax crystals will begin to precipitate when the temperature of the fuel decreases. If a certain amount of wax precipitates, the crystals can block fuel flow through filters and other restricted passages in the fuel system. The cold filter plugging point is the temperature of a fuel at which the sample fails to pass the filter.
The Note describes the full preparation and testing process for a sample using the Callisto 100. A specimen of the sample was cooled under specified conditions and, at intervals of 1 °C, drawn into a pipette under a controlled vacuum through a standardised wire mesh filter. The procedure was repeated as the specimen continues to cool, for each 1 °C below the first test temperature. Testing continued until the amount of wax crystals that separated out of solution was sufficient to stop or slow down the flow so that the time taken to fill the pipette exceeded 60 seconds or the fuel failed to return completely to the test jar before the fuel had cooled by a further 1 °C.
