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Seat the perforated disk on the ledge in the permeability cell, inscribed or marked face down. Place a filter paper disk on the metal disk, and press the edges down with a rod having a diameter slightly smaller than that of the cell. Measure the mass to the nearest 0.001 grams, the quantity of cement determined in accordance with 5.4 of the written standard, and place in the cell. Tap the side of the cell lightly in order to level the bed of cement. Place a filter paper disk on top of the cement, and compress the cement with a plunger until the plunger collar is in contact with the top of the cell. Slowly withdraw the plunger a short distance, rotate about 90 degrees, repress, and then slowly withdraw. Use of fresh paper filter disks is required for each determination. Attach the permeability cell to the manometer tube, making certain that an airtight connection is obtained, note 6 of the written standard, and taking care not to jar or disturb the prepared bed of cement. Slowly evacuate the air in one arm of the manometer U-tube until the liquid reaches the top mark, and then close the valve tightly. Start the timer when the bottom of the meniscus of the manometer liquid reaches the second next to the top mark. And stop when the bottom of the meniscus of liquid reaches the third next to the bottom mark. Note the time interval measured, and record in seconds. Note the temperature of test, and record in degrees Celsius. In the calibration of the instrument, make at least three determinations of the time of flow on each of three separately prepared beds of the standard sample. Note 7 of the written standard-- the calibration shall be made by the same operator who makes the fineness determination. A little stopcock grease should be applied to the standard taper connection. The efficiency of the connection can be determined by attaching the cell to the manometer, stoppering it, partially evacuating the one arm of the manometer, then closing the valve. Any continuous drop in pressure indicates a leak in the system. The sample may be re-fluffed, and reused for preparation of the test bed, provided that it is kept dry and all tests are made within four hours of the opening of the sample.

Video Details

Duration: 2 minutes and 58 seconds
Language: English
License: Dotsub - Standard License
Genre: None
Views: 5
Posted by: abuckmaster on Aug 7, 2019


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