ASTM D6371 for cold filter plugging point of diesel and heating fuels
4. Summary of Test Method
4.1 A specimen of the sample is cooled under specified conditions and, at intervals of 1°C, is drawn into a pipet under a controlled vacuum through a standardized wire mesh filter. The procedure is repeated, as the specimen continues to cool, for each 1°C below the first test temperature. Testing is continued until the amount of wax crystals that have separated out of solution is sufficient to stop or slow down the flow so that the time taken to fill the pipet exceeds 60 s or the fuel fails to return completely to the test jar before the fuel has cooled by a further 1°C.
4.2 The indicated temperature at which the last filtration was commenced is recorded as the CFPP.
5. Significance and Use
5.1 The CFPP of a fuel is suitable for estimating the lowest temperature at which a fuel will give trouble-free flow in certain fuel systems.
5.2 In the case of diesel fuel used in European light duty trucks, the results are usually close to the temperature of failure in service except when the fuel system contains, for example, a paper filter installed in a location exposed to the weather or if the filter plugging temperature is more than 12°C below the cloud point value in accordance with Test Method D2500, D5771, D5772, or D5773. Domestic heating installations are usually less critical and often operate satisfactorily at temperatures somewhat lower than those indicated by the test results.
5.3 The difference in results obtained from the sample as received and after heat treatment at 45°C for 30 min can be used to investigate complaints of unsatisfactory performance under low temperature conditions.
