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ISO 18852-2012 pdf free download

ISO 18852-2012 pdf free download.Rubber compounding ingredients Determination of multipoint nitrogen surface area (NSA) and statistical thickness surface area (STSA)
Ingredients de mélange du caoutchouc — Determination de Ia surface par adsorption d’azote (NSA) et de Ia surface par épaisseur statistique (STSA) par méthode multipoints.
6.1 This procedure shall be performed for the initial calibration, periodically as a quality control measure, and following repairs or adjustments. If a commercial apparatus is used, consult the user’s manual for specific instructions in carrying out the steps which follow.
6.2 Attach the vacuum and pressure gauges or transducers (4.3 and 4.4) to the apparatus and evacuate it, the manifold and all internal pressure/vacuum sensors to 2,7 Pa (20 imHg) or below.
6.3 Verify that the Internal vacuum sensor(s) are reading correctly and that the internal pressure sensor(s) are reading correctly in the vicinity of zero pressure, taking into account the expected resolution and stability limits. Make adjustments as needed.
6.4 Close the vacuum path and admit nitrogen gas to build 100 kPa ± 1 % (750 mmHg ± 7,5 mmHg) of pressure. Verify that the pressure sensors read the correct pressure to within ±0,25 %. Make adjustments as needed.
6.5 Thoroughly clean and dry an empty adsorption cell (4.2). Connect it to the apparatus and evacuate it to
2,7 Pa (20 pmHg). Apply a 300 °C heating mantle and continue evacuation for at least 1 h and until the rate of
pressure rise upon temporarily closing the vacuum path is under 0.4 Pa (3 iimHg) per minute.
6.6 Perform a “blank analysis on this clean empty cell at 0,05: 0,10; 0,15; 0,20 and o.25p1po, Use a ‘po value” of 101,325 kPa (760 mmHg) and a “test portion mass” of 1 g for the calculations.
6.7 Examine the mean value of the ‘adsorbed quantities” obtained. Ideally, this should be zero. A single reading exceeding 0,25 standard cm3 makes the set-up unacceptable. As a rule, only readings below 0.125 standard cm3 are acceptable, although one of them may go as high as 0.25 standard cm3. A parabolic error versus pressure profile might indicate failure to correct property for non-ideal gas behaviour or transducer linearity problems. A linear error profile indicates failure to properly measure or account for unadsorbed gas (free-space error). Erratic variation of data points indicates leaks or noisy measurements.
6.8 Determine the internal volume of the calibration-volume reservoir (4.8) below the valve or stopcock by the difference in mass when empty and then when filled completely with distilled water (5.2). Measure the water temperature and use the correct water density to obtain the exact volume of water contained. It might be necessary to immerse the device in boiling water to ensure complete filling and degassing. Repeat the procedure until the calibration volume is known to better than 0,1 %. Empty the calibration volume and thoroughly dry it overnight in a vacuum oven at 70 C ± 5 °C.
6.9 Connect the calibration-volume reservoir to a sample port of the gas adsorption apparatus, open the valve or stopcock, and evacuate the reservoir to below 2,7 Pa (20 imHg). Continue evacuation for one more hour. Close off the path to the vacuum source and note whether any nse in pressure occurs. The pressure shall remain below 2,7 Pa (20 pmHg). with a rate of increase of less than 0,04 Pa (0,3 imHg) per minute. When this has been achieved, close the valve or stopcock to maintain the vacuum within the calibration-volume reservoir.ISO 18852-2012 pdf free download.

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