ASTM D4539 Test Method for Filterability of Diesel Fuels by Low-Temperature Flow Test (LTFT)
3. Summary of Test Method
3.1 The temperature of a series of test specimens of fuel is lowered at a prescribed cooling rate. Commencing at a desired test temperature and at each 1°C interval thereafter, a separate specimen from the series is filtered through a 17-µm screen until a minimum LTFT pass temperature is obtained. The minimum LTFT pass temperature is the lowest temperature, expressed as a multiple of 1°C, at which a test specimen can be filtered in 60 s or less.
3.2 Alternatively, a single specimen may be cooled as described under 3.1 and tested at a specified temperature to determine whether it passes or fails at that temperature.
4. Significance and Use
4.1 The Low Temperature Flow Test results are indicative of the low temperature flow performance of the test fuel in some diesel vehicles (per CRC Report No. 528). The test method is especially useful for the evaluation of fuels containing flow improver additives.
4.2 The test method can be used to supplement other measurements of diesel fuel low temperature behavior (in accordance with Test Methods D97, D2500, and D3117).
