ASTM D6371 for cold filter plugging point of diesel and heating fuels
8. Sampling
8.1 Unless otherwise specified in the commodity specification, samples shall be taken as described in Practice D4057 or D4177 in accordance with the requirements of national standards or regulation for the sampling of the product under test, or both.
9. Preparation of Test Specimen
9.1 Filter approximately 50 mL of the sample (see 8.1) at laboratory ambient temperature, but in any case not at a temperature less than 15°C, through dry filter paper (see 7.3).
10. Preparation of Apparatus
10.1 Prepare the manual apparatus or the automated apparatus for operation in accordance with the manufacturer's instructions for calibrating, checking, and operating the equipment. See Fig. 1 for manual apparatus.
10.2 Before each test, dismantle the filter unit (see 6.1.8.2) and wash the pieces and the test jar (see 6.1.2), the pipet (see 6.1.8.1) and the thermometer (see 6.1.9 for manual apparatus and 6.2 for platinum resistance used in automated equipment) with heptane (see 7.1), then rinse with acetone (see 7.2) and dry in a stream of filtered air. Check the cleanliness and dryness of all elements, including the jacket (see 6.1.3). Examine the wire mesh (see 6.1.8.2(c)) and the joints (see 6.1.8.2(a) and 6.1.8.2(b) for damage; if necessary renew them.
10.3 Check that the screw cap (see 6.1.8.2(b) is tight enough to prevent leakage.
11. Calibration and Standardization
11.1 Adjust the automated CFPP apparatus (when used) in accordance with the manufacturer's instructions.
11.2 Calibrate the temperature measuring device in accordance with the manufacturer's instructions.
11.3 Periodically verify the correct functioning of manual and automated apparatus using a certified reference material or in-house secondary reference material, such as fuel of known CFPP value.
NOTE 6 - It is preferable that verification be carried out at least two times a year, where possible, using certified reference materials. The apparatus should be checked more frequently (for example, weekly) using a secondary verification material.
11.4 When the CFPP values obtained using a verification material deviate by more than the test repeatability (see 15.2), or an unacceptable statistical quality control bias is observed, check the condition and operation of the apparatus to ensure conformity with the specification as stated in this test method. The manufacturer's instruction manual should provide guidance on ensuring that the apparatus is correctly set up and calibrated.
