EN 12662 Liquid petroleum products - Determination of total contamination in middle distillates, diesel fuels and fatty acid methyl esters
7 Cleansing of sample containers and filtration apparatus
IMPORTANT - Due to the extremely low levels of material being measured, it is essential that this testing is performed in a clean environment to minimize the possibility of contamination.

7.1 Clean strictly, in the manner described in 7.2 to 7.7, all the surfaces of all components of the sample containers and parts of the apparatus that are:
a) likely to come into contact with the sample or heptane (5.1), or
b) capable of transferring extraneous matter to the filter.

7.2 Wash with warm tap water containing water soluble detergent.

7.3 Rinse thoroughly with warm tap water.

7.4 Rinse thoroughly with water, handling container caps externally only with clean laboratory tongs or gloves during this and subsequent washings.

7.5 Rinse thoroughly with propan-2-ol (5.3).

7.6 Rinse thoroughly with heptane (5.1).

7.7 Cover the top of the sample container and the funnel opening of the assembled filtration apparatus (6.1) with clean plastic film or aluminium foil (6.17) previously rinsed with heptane (5.1) and air-dried.

8 Sampling
8.1 Unless otherwise specified, obtain samples in accordance with the requirements of EN ISO 3170, EN ISO 3171, EN 14275, or an equivalent national standard.

8.2 The preferred procedure is to take samples dynamically from a sampling loop in a distribution line or from the flushing line of an automatic pipeline sampling device in accordance with the principles specified in EN ISO 3171. Ensure that the line to sampler is flushed with fuel before taking the sample.

8.3 If samples are taken manually the samples shall be taken directly into the sample container (6.15).

8.4 Where it is only possible to obtain samples from static storage follow the procedures given in EN ISO 3170, ensuring that the final sample has not passed through intermediate containers prior to placement in the prepared container.

8.5 Glass containers shall be used to take and store the samples. These containers should be cleaned according to Clause 7. Glass is used in order to facilitate the visual surveillance of the sample homogenisation before subsequent analysis. Ensure that the samples receive the minimum exposure to light. Use either brown glass containers or shield the samples from light during transportation and storage. To facilitate sampling from refuelling nozzles, wide necked bottles should be used.

8.6 Fill the sample container to between 80 % and 85 % of its capacity.

8.7 The collected sample shall be homogenised according to the procedure given in 9.2.4 before any other analytical measurements are carried out, to avoid non-representative sampling when this method is performed.

9 Preparation of the test portion
9.1 General
Make sure that the sample container (6.15) is free of adhering particles which can distort the analysis. In case of doubt, rinse the outside of the container and its closure with water and propan-2-ol (5.3), as described in 7.2 to 7.5, to remove any adhering particles and avoid introducing undesirable contamination in the test sample.

9.2 Middle distillates and diesel fuels
9.2.1 Loosen the sample container closure and place the container and its content in a water bath or oven (6.11) at 40 °C for 30 min to 60 min to ensure that any components that have separated out have dissolved again.

9.2.2 Remove the sample container from the water bath or oven and tighten the container closure. Let it cool down to room temperature. Wash the outside of the container with propan-2-ol.

9.2.3 Place the beaker (6.3) onto the balance (6.13) and tare.

9.2.4 Shake the sample container for at least 10 s, one-to-two strokes per second, using 10 cm to 25 cm strokes. Invert the container and continue to shake for at least a further 10 s, then re-invert and shake for at least a further 10 s. If there are any visible signs of contaminant adhering to the container walls, repeat shaking procedure. The use of a mixer is not allowed.

9.2.5 Weigh into the beaker a test portion equivalent to approximately 300 ml. The sample shall be poured very quickly into the beaker, without trying to get a volume as close as possible to 300 ml. Record the mass of the test portion mE to the nearest 0.1 g.

9.3 Neat FAME
9.3.1 Loosen the sample container closure and place the container and its content in a water bath or oven (6.11) at 60 °C for at least 2 h to 2.5 h to ensure that any components that have separated out have dissolved again.

9.3.2 Remove the sample container from the water bath or oven and tighten the container closure. Let it cool down to room temperature. Wash the outside of the container with propan-2-ol.

9.3.3 Place the 1 l bottle (6.5) onto the balance (6.13) and tare.

9.3.4 Shake the sample container for at least 10 s, one-to-two strokes per second, using 10 cm to 25 cm strokes. Invert the container and continue to shake for at least a further 10 s, then re-invert and shake for at least a further 10 s. If there are any visible signs of contaminant adhering to the container walls, repeat shaking procedure.

The use of a mixer is not allowed.

9.3.5 Weigh into the bottle a test portion equivalent to approximately 300 ml. The sample shall be poured very quickly into the bottle, without trying to get a volume as close as possible to 300 ml. Record the mass of the test portion mE to the nearest 0.1 g.

9.3.6 Add 300 ml of the solvent (5.4) by means of a 500 ml graduated cylinder (6.4). Mix thoroughly and leave at ambient temperature for 2 h before filtration.

9.4 Liquid petroleum products with a kinematic viscosity exceeding 8 mm2/s at 20 °C, or 5 mm2/s at 40 °C
9.4.1 Loosen the sample container closure and place the container and its content in a water bath or oven (6.11) at 40 °C for 30 min to 60 min to ensure that any components that have separated out have dissolved again.

9.4.2 Remove the sample container from the water bath or oven and tighten the container closure. Let it cool down to room temperature. Wash the outside of the container with propan-2-ol.

9.4.3 Place the 1 l bottle (6.5) onto the balance (6.13) and tare.

9.4.4 Shake the sample container for at least 10 s, one-to-two strokes per second, using 10 cm to 25 cm strokes. Invert the container and continue to shake for at least a further 10 s, then re-invert and shake for at least a further 10 s. If there are any visible signs of contaminant adhering to the container walls, repeat shaking procedure.

The use of a mixer is not allowed.

9.4.5 Weigh into the bottle a test portion equivalent to approximately 300 ml. The sample shall be poured very quickly into the bottle, without trying to get a volume as close as possible to 300 ml. Record the mass of the test portion mE to the nearest 0.1 g.

9.4.6 Dilute the weighed sample portion (mE) with heptane (5.1) to a kinematic viscosity not exceeding 8 mm2/s at 20 °C, or 5 mm2/s at 40 °C. Mix thoroughly.

10 Preparation of the equipment
10.1 Preparation of the filtration apparatus
10.1.1 Visually check that the filtration apparatus (6.1) is clean both internally and externally. If not clean, repeat in accordance with Clause 7.

10.1.2 Follow all existing safety precautions and earth the apparatus to avoid electrostatic build-up and discharge.

10.1.3 Assemble the filtration apparatus (6.1) without the filter (6.2) and wash the inside with heptane (5.1). Ensure seal between filter holder and receiving flask, and between tube, hose and wire and safety flask with appropriate sealant.

10.2 Preparation of the filter
10.2.1 For all operations handle the filter (6.2) by the edge using forceps (6.10).

10.2.2 Place the filter (6.2) properly centred on to the filter holder of the pre-cleaned apparatus. Rinse the filter (6.2) with heptane (5.1) and apply vacuum. Release the vacuum slowly and then remove carefully the filter from the filter holder by means of the forceps (6.10), place it on the Petri dish (6.8) and place in the oven (6.6) at 110 °C +/- 5 °C for at least 45 min. Use the cover during transport to the oven, remove the cover when the Petri dish is placed in the oven. Check carefully that the filter is centred on the filter holder. The filter shall not be damaged by the filter holder equipment. Damaged filters affect the mass of the filter and lead to erroneous results.

10.2.3 Remove the Petri dish (6.8) and filter from the oven (6.6), apply the cover and cool in the desiccator (6.7), located near to the analytical balance (6.9), for approximately 45 min.

10.2.4 Immediately before the determination, remove the filter (6.2) from the Petri dish (6.8) and using the analytical balance (6.9) weigh the filter to the nearest 0.1 mg. Record this mass m1.

10.2.5 Place the filter (6.2) directly on to the filter holder of the pre-cleaned apparatus and fix the funnel with the clamp. Rinse the filter with heptane (5.1). Ensure that the filter is free from bubbles and is firmly fixed between the round surfaces of the filter apparatus.