ASTM D6217 for Particulate Contamination in Middle Distillate Fuels by Laboratory Filtration
8. Preparation of Apparatus and Sample Containers
8.1 Clean all components of the filtration apparatus, sample containers, their caps and petri dishes as described in 8.1.1-8.1.7.
8.1.1 Remove any labels, tags, and so forth.
8.1.2 Wash with warm tap water containing detergent.
8.1.3 Rinse thoroughly with warm tap water.
8.1.4 Rinse thoroughly with reagent water. Container caps should be handled only externally with clean laboratory crucible tongs during this and subsequent washings.
8.1.5 Rinse thoroughly with propan-2-ol that has been filtered through a 0.45 µm membrane filter.
8.1.6 Rinse thoroughly with filtered flushing fluid and dry.
8.1.7 Keep a clean protective cover (the cover may be rinsed with filtered flushing fluid), over the top of the sample container until the cap is installed. Similarly protect the funnel opening of the assembled filtration apparatus with a clean protective cover until ready for use.
9. Sampling
NOTE 8 - Caution - It is important to note that the entire contents of the sample container are filtered during the conduct of this test method. This includes not only all of the fuel but also all rinsings of the interior of the container with flushing fluid. Because of this, take care to protect the sample from any external contamination.
9.1 The sample container shall be 1 L (+/- 0.15 L) in volume and have a screw on cap. Glass containers are preferred to facilitate a visual inspection of the contents and the container before and after filling. Glass containers also allow for visual inspection of the container, after the sample is emptied, to confirm complete rinsing of the container. Epoxy lined sample cans, polytetrafluoroethylene (PTFE) bottles, and high density linear polyethylene bottles have also been found suitable as sample containers but are less desirable since visual inspection of the interior of the container is more difficult.
9.2 All containers and their caps, sampling lines, and other equipment used in obtaining the sample for analysis shall be thoroughly cleaned as described in Section 8. When it is not practical to clean the sample containers in this manner, the containers shall be rinsed three times with the fuel to be sampled. When it is not practical to clean the sampling lines, rinse them thoroughly with the fuel to be sampled.
9.3 Precautions to avoid sample contamination shall include selection of an appropriate sampling point. Samples should preferentially be obtained dynamically from a sampling loop in a distribution line, or from the flushing line of a field sampling kit. Ensure that the line to be sampled is flushed with fuel before taking the sample.
9.3.1 Where it is desirable or only possible to obtain samples from static storage, follow the procedures given in Practice D4057 or equivalent, taking precautions for cleanliness of all equipment used. Ensure that the sample has not passed through intermediate containers prior to placement in the prepared container.
NOTE 9 - Caution - Samples obtained from static storage may give results which are not representative of the bulk contents of the tank because of particulate matter settling. Where possible, the contents of the tank should be circulated or agitated before sampling, or the sampling performed shortly after a tank has been filled.
9.4 Visually inspect the sample container before taking the samples to verify that there are no visible particles present inside the container. Fill the sample container 95 volume % full, leaving space for vapor expansion. Protect the fuel sample from prolonged exposure to light by wrapping the container in aluminum foil or storing it in the dark to reduce the possibility of particulate formation by light-promoted reactions. Do not transfer the fuel sample from its original sample container into an intermediate storage container. If the original sample container or damaged or leaking, then a new sample must be obtained.
9.5 Analyze fuel samples as soon as possible after sampling. When a fuel cannot be analyzed within one day, blanket it with an inert gas such as oxygen-free nitrogen, argon, or helium and store it at a temperature no higher than 10°C (50°F), except for samples with cloud points above 10°C which are to be stored at a temperature 2°C above their cloud point.
10. Preparation of Membrane Filters
10.1 Each set of test filters consists of one test membrane filter and one control membrane filter. For fuels containing little particulate materials, only one set of filters is required. If the fuel highly contaminated, more than one set of filters may be required (see Section 11). The two membrane filters used for each individual test shall be identified by marking the petri dishes used to hold and transport the filters. Clean all glassware used in preparation of membrane filters as described in 8.1.
10.1.1 Using forceps place the test and control membrane filters side by side in a clean petri dish. To facilitate handling, the membrane filters should rest on clean glass support rods, or watch glasses, in petri dish.
10.1.2 Place the petri dish with its lid slightly ajar, in a drying oven at 90 +/- 5°C and leave it for 30 min.
10.1.3 Remove the petri dish from the drying oven and place it near the balance. Keep the petri dish cover ajar, but such that the membrane filters are still protected from contamination from the atmosphere. Allow 30 min for the membrane filters to come to equilibrium with room air temperature and humidity.
10.1.4 Remove the control membrane filter from the petri dish with forceps, handling by the edge only, and place it centrally on the weighing pan of the balance. Weigh it, record the initial mass to the nearest 0.0001 g, and return it to the petri dish.
10.1.5 Repeat 10.1.4 for the test membrane filter.
10.1.6 Using clean forceps, place the weighed control membrane filter centrally on the membrane filter support of the filtration apparatus (see Fig. 1). Place the weighed test membrane filter on top of the control membrane filter. Install the funnel and secure with locking ring or spring clip. Do not remove the plastic film from the funnel opening until ready to start filtration.
