ASTM D6217 for Particulate Contamination in Middle Distillate Fuels by Laboratory Filtration
11. Procedure
11.1 Thoroughly clean the outside of the sample container in the region of the cap by wiping it with a damp, lint-free cloth. Shake the container vigorously for about 1/2 min.
11.2 Remove the cap and remove any external contaminant that may be present in the treads.
11.3 Complete assembly of the receiving flask, pre-weighed filters and funnel as a unit (see Fig. 1). To minimize operator exposure to fumes, the filtering procedure should be performed in a fume hood. The entire contents of the sample container shall be filtered through the membrane filters to ensure a correct measure of the particulate contamination in the sample.
NOTE 10 - Some fuels may filter reasonably rapidly during transfer of the total contents of the sample container through a single set of filter membranes. However, some fuels, due to the quantity or nature of particulates, or both, may plug the membrane filter during filtration and require use of multiple successive filtrations. To facilitate the latter, it is advisable to use smaller cleaned graduated transfer cylinders of 100 mL capacity.
11.4 Pour fuel from the sample container to the graduated cylinder, start the vacuum and then transfer 100 mL of fuel to the filter funnel.
11.4.1 Continue transferring 100 mL increments of fuel to the filter funnel. When all the fuel from the sample container has been filtered, or if filtration slows so that 100 mL of sample requires greater than 10 min for complete filtration, then remove the filter support/filter funnel from the receiving flask and pour the filtered fuel into a clean graduated cylinder and record the volume of fuel in mL that was filtered. Keep the fuel sample filtrate separate from the solvent washings filtrate. This allows the fuel to be used for additional analyses. If all the fuel has been filtered, thoroughly rinse the sample container and the graduated cylinder with one or more portions of filtered fiushing fluid and pour the rinses into the funnel and proceed to 11.4.2. If all the fuel has not been filtered, then proceed to 11.4.2 and 11.4.3 and then repeat from 11.4.1.
11.4.2 Wash down the inside of the funnel and the outside of the joint between the funnel and filter base filtered with flushing fluid. With the vacuum applied, carefully separate the funnel from the filter base. Wash the periphery of the membrane filter by directing a gentle stream of filtered flushing fluid from the edge to the center, exercising care not to wash any of the particulate from the surface of the membrane filter. Maintain vacuum after the final washing for 10 to 15 s to remove excess filtered flushing fluid from the membrane filter.
11.4.3 Using clean forceps, carefully remove the test and control membrane filters from the filter base and place them side by side on clean glass support rods or watch glasses in a clean, covered petri dish. Dry and reweigh the membrane filters as described in 10.1.5, taking care not to disturb the particulate on the surface of the test membrane filter. Record the final control membrane filter mass and the final test membrane filter mass to the nearest 0.0001g for each filtration.
