ISO 3262-19:2021 pdf download – Extenders — Specifications and methods of test — Part 19: Precipitated silica.
6.3.8  Desiccator, containing for example magnesium perchlorate as desiccant. 6.4  Procedure 6.4.1  Number of determinations Carry out the determination in duplicate. 6.4.2  Test portion Weigh, to the nearest 0,2 mg, approximately 1 g (m 0 ) of the sample (see Clause 5) into a dish (6.3.1). 6.4.3  Determination Slowly add 20 ml of concentrated hydrochloric acid (6.2.1) and evaporate to dryness under the infrared evaporator (6.3.4). Add again 20 ml of concentrated hydrochloric acid and evaporate to dryness. Repeat this step once more. After the third evaporation, place the dish in the drying oven (6.3.6), maintained at (140 ± 5) °C, and leave for 2 h. Remove the dish from the oven and allow to cool. Add 50 ml of 1 + 1 hydrochloric acid (6.2.2) to the residue in the dish and warm it for approximately 20 min on the water bath (6.3.3) at 100 °C. Filter through a suitable filter paper (6.3.7) and wash the residue on the filter with hot water until the washings are neutral. Pour the filtrate and washings into the original dish and evaporate to dryness. Repeat this evaporation step another two times, adding each time 10 ml of concentrated hydrochloric acid to the residue. After the third evaporation, heat at (140 ± 5) °C for 2 h in the drying oven. Add 20 ml of 1 + 1 hydrochloric acid to the residue in the dish and warm it for approximately 10 min on the water bath at 100 °C. Filter through a fresh filter paper and wash the residue on the filter with hot water until the washings are neutral.
8.2  Materials 8.2.1  Tap water, filtered, at a pressure of approximately 200 kPa above atmospheric pressure. The pressure shall be adjusted to give a flow rate of (13,5 ± 0,3) l/min from the spray head. 8.3  Apparatus Use ordinary laboratory apparatus and glassware, together with the following. 8.3.1  Sieve, consisting of a metal frame and wire gauze made from phosphor bronze or stainless steel, mesh size 45 µm, diameter 200 mm. NOTE Loss of suspension by splashing during the sieving procedure can be prevented by using a splash guard made of a cylindrical metal sheet made from phosphor bronze or stainless steel having a height of approximately 200 mm and a diameter slightly less than 200 mm which fits into the top of the sieve. 8.3.2  Sieve holder. 8.3.3  Spray head, with a diameter of 60 mm, having 76 holes drilled with a diameter of (1,0 ± 0,1) mm. 8.3.4  Weighing bottle. 8.3.5  Drying oven, capable of being maintained at (105 ± 2) °C. 8.4  Procedure 8.4.1  Number of determinations Carry out the determination in duplicate. 8.4.2  Test portion Weigh, to the nearest 0,1 mg, a quantity (m 0 ) of the sample (see Clause 5) such that a sufficient residue is obtained on the sieve (8.3.1). Place this test portion in a suitable beaker. Generally, a test portion of 10 g to 100 g is necessary.