ISO 3405:2011 pdf free download – Petroleum products – Determination of distillation characteristics at atmospheric pressure.
6.2 Sample maintenance prior to testing
6.2.1 General
Unless otherwise specified, sampling shall be carried out in accordance with ISO 3170 or ISO 3171, bearing in mind the special conditions described in Table 1. Maintain samples prior to testing at the specified temperatures given in Table 1, away from sources of direct heat or sunlight.
6.2.2 Groups I and 2
Collect the sample in a container previously cooled to below 10 °C. Condition the container, preferably by immersing it in the liquid, where possible, and discarding the first sample. Where immersion is not possible, the sample shall be drawn off into the previously cooled container so that agitation is kept at a minimum. Close the container immediately with a tight-fitting stopper, and place the sample in an ice bath or refrigerator to maintain the sample below the specified temperature. Maintain the sample below 10 °C prior to testing, and preferably store at or below this temperature. Where maintenance and/or storage at below 10 °C is not possible or practicable, a temperature of up to 20 °C is acceptable provided that the sample is always conditioned to a temperature below 10 °C before the container is opened.
6.2.3 Groups 3 and 4
Maintain the sample at ambient temperature. If the sample is not fluid at ambient temperature, maintain it at a temperature of 9 °C to 21 °C above its pour point. Shake the sample vigorously prior to subsampling to ensure homogeneity, and disregard the temperature range shown in Table 2 for the receiving cylinder. Prior to analysis, heat the receiving cylinder to approximately the same temperature as the sample, and pour the heated test portion precisely to the 100 ml mark. Transfer the test portion as rapidly and completely as possible to the distillation flask.
6.3.1 General
Samples of materials that are visibly hazy (suspended water) or are suspected of containing water are not
suitable for testing.
6.3.2 Groups I and 2
If the sample is not dry, obtain another sample for testing that is free from suspended water. If such a sample cannot be obtained, add a sufficient amount of anhydrous sodium sulfate or other suitable drying agent to the sample maintained at 0 °C to 10 °C, and physically remove the water by shaking. Once the sample shows no visible signs of water, use a decanted portion of the sample, maintained at 0 °C to 10 °C, for the analysis. Record the fact that the sample has been dried by desiccant.
NOTE Data from a round-robin exercise show that suspended water in hazy samples in groups 1 and 2 can be removed by the above procedure without statistically affecting the results of the test.
6.3.3 Groups 3 and 4
In cases where a water-free sample is not practical, remove the suspended water by shaking the sample with anhydrous sodium sulfate or another suitable drying agent, and separate it from the drying agent by decantation.
7 Preparation of apparatus
7.1 Refer to Table 2 and prepare the apparatus by choosing the appropriate distillation flask, temperature-measurement system and flask-support board as required for the indicated group. If gas heating is used, use a Type 1 flask-support (5.6.1); if electric heating is used, use a Type 2 flask-support (5.6.2). Bring the
temperature of the receiving cylinder, the flask, the temperature sensor and the cooling bath to the indicated
temperatures.
7.2 Make any necessary provisions so that the temperature of the cooling bath and receiving cylinder are maintained at their specified temperatures. The receiving cylinder shall be positioned in a bath such that either the liquid level is at least as high as the 100 ml mark or the entire receiving cylinder is surrounded by an aircirculation chamber.
For groups 1, 2 and 3, use suitable media for low-temperature baths such as chopped ice and water, refrigerated brine and refrigerated ethylene glycol.