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D2500_17_8

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Bring the sample to be tested to a temperature at least 14 degrees Celsius above the expected cloud point. Remove any moisture present by a method, such as filtration, through dry, lintless filter paper until the oil is perfectly clear. But make such filtration at a temperature of at least 14 degrees Celsius above the approximate cloud point. Pour the sample into the test jar to the level mark. If using a liquid-in-glass thermometer and the expected cloud point is above minus 36 degrees Celsius, then use the high cloud and pour point thermometer. Otherwise, use the low cloud and pour thermometer. Close the test jar tightly by the cork carrying the test thermometer, and adjust the position of the cork and the thermometer so that the cork fits tightly. The thermometric device and the jar are co-axial, and the thermometer bulb or probe is resting on the bottom of the jar. Liquid column separation of thermometers occasionally occurs and may escape detection. Thermometers should be checked periodically and used only if their ice points are 0 degrees Celsius plus or minus 1 degrees Celsius when the thermometer is immersed to the immersion line in an ice bath, and when the emergent column temperature does not differ significantly from 21 degrees Celsius. Alternatively, immerse the thermometer to a reading and correct for the resultant cooler stem temperature. See that the disk, gasket, and the inside of the jacket are clean and dry. Place the disk in the bottom of the jacket. The disk and jacket shall have been placed in the cooling medium a minimum of 10 minutes before the test jar is inserted. The use of a jacket cover while the empty jacket is cooling is permitted. Place the gasket around the test jar 25 millimeters from the bottom. Insert the test jar in the jacket. Never place a jar directly into the cooling medium. Failure to keep the disk, gasket, and the inside of the jacket clean and dry may lead to frost formation, which may cause erroneous results. Maintain the temperature of the cooling bath at 0 degrees Celsius plus or minus 1.5 degrees Celsius. At each test thermometer reading that is a multiple of 1 degree Celsius, remove the test jar from the jacket quickly, but without disturbing the specimen. Inspect for cloud and replace in the jacket. This complete operation shall require not more than three seconds. If the oil does not show a cloud when it has been cooled to 9 degrees Celsius, transfer the test jar to a jacket in a second bath maintained at a temperature of minus 18 degrees Celsius plus or minus 1.5 degrees Celsius. See Table 2 of the written standard. Do not transfer the jacket. If the specimen does not show a cloud when it has been cooled to minus 6 degrees Celsius, transfer the test jar to a jacket in a third bath maintained at a temperature of minus 33 degrees Celsius plus or minus 1.5 degrees Celsius. For the determination of very low cloud points, additional baths are required. Each bath to be maintained in accordance with Table 2 of the written standard. In each case, transfer the jar to the next bath if the specimen does not exhibit cloud point and the temperature of the specimen reaches the lowest specimen temperature in the range identified for the current bath in use based on the ranges stated in Table 2 of the written standard. Report the cloud point to the nearest 1 degrees Celsius at which any cloud is observed at the bottom of the test jar, which is confirmed by continued cooling. A wax or haze is always noted first at the bottom of the test jar where the temperature is lowest. A slight haze throughout the entire sample, which slowly becomes more apparent as the temperature is lowered, is usually due to traces of water in the oil. Generally, this water haze will not interfere with the determination of the wax cloud point. In most cases of interference, filtration through dry lintless filter papers, such as described in 8.1 of the written standard, is sufficient. In the case of diesel fuels, however, if the haze is very dense, a fresh portion of the sample should be dried by shaking 100 milliliters with 5 grams of anhydrous sodium sulfate for at least five minutes, and then filtering through dry lintless filter paper. Given sufficient contact time, this procedure will remove or sufficiently reduce the water haze so that the wax cloud can be readily discerned. Drying and filtering should be done always at a temperature at least 14 degrees Celsius above the approximate cloud point, but, otherwise, not in excess of 49 degrees Celsius.

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Duration: 5 minutes and 37 seconds
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Language: English
License: Dotsub - Standard License
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Views: 5
Posted by: abuckmaster on Aug 23, 2018

D2500_17_8

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