ASTM D2068 Test Method for Filter Plugging Tendency of Distillate Fuel Oils
6. Apparatus
6.1 The apparatus is shown diagrammatically in Fig. 1 and is comprised of the following parts:
6.1.1 Pump, capable of delivering fuel at a constant rate of 20 +/- 1 mL/min, and incorporating a pulse damping mechanism to produce smooth flow.
6.1.2 Pressure Gage - Gage or equivalent pressure recording device calibrated and graduated 0 to 210 kPa (2 kPa graduations, minimum).
6.1.3 Filter Unit - Stainless steel body, 13–mm diameter, shown diagrammatically in Fig. 2.
6.1.4 Filter Medium - Glass fiber filter, nominal pore size 1.6 µm, 13-mm diameter.
6.1.5 Fuel Reservoir and Collection Containers - Graduated glass beakers or cylinders, 400 mL capacity.
6.2 Thermometer, general purpose type, range 0 to 60°C.
6.3 Measuring Cylinder, nominal capacity 500 mL.
6.4 Forceps, spade ended.
6.5 Stopwatch, manual or electronic, nominal accuracy 0.2 s.
7. Sampling
7.1 The laboratory fuel sample from which an aliquot is being drawn for the purposes of this test must be representative of the lot of fuel, whether the fuel is in a storage tank, a tank car, a pipeline, or other container. The laboratory sample should therefore have been obtained by following the practices of Practices D4057, D4177, or similar standard. The maximum sample size is dictated by the quantity that can be mixed thoroughly (see 9.2).
7.2 Draw a representative 1 to 2 L aliquot from the thoroughly mixed laboratory sample into an epoxy-lined can or dark glass bottle that has been previously rinsed three times with the product to be sampled.
NOTE 2 - Caution: Because the situations under which samples are taken vary from laboratory to laboratory and from situation to situation, no firm recommendations for sampling can be given. It is the responsibility of the user of this test method to ensure the representativeness of the aliquot used in this test.
8. Preparation of Apparatus
8.1 Calibration - Calibration is required when a new batch of filter media is used, when there is doubt concerning the validity of a test result, or when the apparatus has not been used for 3 months. A procedure for the preparation of standard solutions for the apparatus calibration is given in Annex A1 to this test method.
8.2 Apparatus Assembly - Assemble the apparatus as shown in Fig. 1 without the filter unit connected. To ensure that the pump and pipework are clean and to calibrate the pump, fill the fuel reservoir with fuel that has been previously filtered through a glass fiber filter medium. Measure the delivery rate of the pump by timing the removal of 200 mL of fuel from the reservoir. If the time is not 600 +/- 30 seconds, adjust and repeat.
8.3 Filter Unit Assembly - Assemble the filter unit as shown in Fig. 2 using a new glass fiber filter medium handled with the forceps, taking care not to damage the filter medium. The medium is placed into the holder with the face marked with a grid pattern uppermost.
NOTE 3 - Caution: It is most important that the filter unit components are assembled as above, and in the exact configuration shown in Fig. 2, because any leakage would yield erroneous results.
