This standard is applicable to the determination of the content of un-loosened cotton, sand, semi-loosened cotton, loosened cotton and dust less than 0.075 mm in machine-selected grade 3 to grade 7 chrysotile asbestos. GB/T 8073-1987 Wet determination method for the looseness of chrysotile asbestos GB/T8073-1987 Standard download decompression password: www.bzxz.net

UDC666.198.01:620.168
National Standard of the People's Republic of China
GB8073-87
Method of wet determination for loftiness of chrysotile asbestos
Published on July 15, 1987
Published by the State Bureau of Standards
Implemented on February 1, 1988
National Standard of the People's Republic of China
Method of wet determination for loftiness of chrysotile asbestos
Loftiness of chrysotile asbestos
UDC666.198.01
GB807387
This standard is applicable to the determination of unloosened cotton, sand, semi-loose cotton, loose cotton and dust less than 0.075 mm in machine-selected grade 3 to grade 7 chrysotile asbestos.
1 Method Overview
This method is to place a quantitative amount of asbestos fibers dispersed in water in a container with a constant rising water velocity. As the asbestos fibers and gravel with different degrees of looseness are separated into several different components due to different movement conditions under the action of water flow, the degree of asbestos looseness is expressed by the proportion of each component to the total amount of the sample.
2 Sample preparation
2.1 Prepare three samples of about 3g in accordance with GB8072-87 "Chrysotile Asbestos Sampling and Sample Preparation Methods". 2.2 Place the sample in a drying oven, dry it at 105-110℃ to constant weight, transfer it to a F desiccator to cool, weigh 2.5±0.005g of the sample and put it in a plastic bag.
3 Equipment and apparatus
3.1 Asbestos looseness wet tester. It is mainly composed of a sedimentation cylinder, an elutriation cylinder, a collector, a stirring device, a water supply and drainage pipe and a frame. The aperture of the sieve plate in the sedimentation cylinder is 0.063mm and the diameter is 100mm; the aperture of the sieve in the collector is 0.075mm. The schematic diagram of the asbestos looseness wet tester is as follows. Approved by the State Bureau of Building Materials Industry on July 2, 1987, and implemented on February 1, 1988
GB8073-87
1-Stirring device; 2-Flowmeter: 3-Sedimentation vessel: 4-Sedimentation vessel seat 5-Elutriator: 6-Sieve rack: 7-Sieve
3.2 Main instruments
3.2.1 A 2000ml cup.
3.2.2 A balance with a sensitivity of 0.001g.
3.2.3 Constant temperature drying oven, 0~250℃.
3.2.4 Dryer.
3.2.5 Sample box.
3.2.6 Beaker, 500ml.
4 Test steps
GB8073—87
4.1 Pour a weighed sample into a beaker containing 400ml of water, soak for 4min, and stir with a bakelite stick for 1min. 4.2 While soaking the sample, wet the sieve plate with a pore size of 0.063mm, place it on the rubber gasket at the bottom of the sedimentation cylinder, and tighten the cylinder so that the overflow water falls exactly on the inclined surface of the elutriation cylinder inlet. 4.3 Close the drain valve under the sedimentation cylinder and place the water inlet pipe that also serves as the stirring rod into the sedimentation cylinder as low as possible. Open the water control valve and block the outlet of the auxiliary water supply pipe with your finger for a moment to remove the air in the stirring rod water inlet pipe. When the sedimentation cylinder is filled with one-third, close the water control valve.
4.4 Pour the soaked sample into the sedimentation cylinder and rinse the beaker. Open the water control valve and adjust the water flow rate to 295±5L/h. Start stirring and start timing. When each container is filled with water, make sure that the water overflows around each container. Otherwise, wet the container with your fingers to eliminate surface tension.
4.5 Within 10 minutes of starting the test, use a rubber scraper to collect excess loose fibers on one side of the test sieve to prevent the sieve holes from clogging and overflowing.
4.660 After 1 minute, turn off the stirring motor and lift the stirring handle so that it is about 25mm below the overflow port of the container. Open the drain valve under the sedimentation cylinder and turn down the water control valve to a flow rate of 90L/h. When the water in the sedimentation cylinder is emptied, completely close the water control valve. 4.7 Unscrew the sedimentation cylinder and take out the sieve plate with unloosened cotton and sand and let it dry. Put the sedimentation cylinder back to its original place, but it doesn't matter. If there is a small amount of obviously loosened fibers in the product, they should be taken out and placed together with the loosened fiber product. Be careful not to take out the unloosened and loosened asbestos fibers together.
4.8 Take out the loosened cotton in the collector, put it in the sample box, and wait for drying. 4.9 Place a 2000ml cup under the elutriation cylinder, gently open the valve, and quickly discharge the semi-loosened cotton and water. When the cup is two-thirds full, slowly close the valve. Pour the material in the cup into the collector for filtration. Repeat this step until the elutriation cylinder is emptied and cleaned. Finally, put the filtrate into the sample box for drying. 4.10 Place the above three products in a drying oven at a temperature of 105~110℃, dry to constant weight, and then move to the lower dryer to cool. Then weigh to an accuracy of 0.005g.
5 Result calculation
5.1 Calculate the percentage of unloosened cotton and sand, semi-loose cotton, and loose cotton in the original sample. Accurate to 0.005. The average value of the difference between the corresponding percentages obtained in the two tests is not more than 3% is the test result. 5.2 The dust content less than 0.075 mm is the difference between the original sample amount and the sum of the products, and is expressed as a percentage. It is accurate to 0.005. Additional remarks:
This standard is under the jurisdiction of Xianyang Nonmetallic Mineral Research Institute of State Building Materials Industry Bureau. This standard was drafted by Xianyang Nonmetallic Mineral Research Institute of State Building Materials Industry Bureau. The drafter of this standard is Zhao Guirong. bzxZ.net
People's Republic of China
National Standard
Wet determination method of looseness of chrysotile asbestos
GB8073-87
Published by China Standards Press
(Beijing Fuwai Sanlihe)
Printed by Beijing Printing House of China Standards Press Distributed by Xinhua Bookstore Beijing Distribution Office Sold by Xinhua Bookstores in various places Copyright is exclusive and may not be reproduced
Format 880×12301/16 Printing sheet 1/2 Number of words 6000 First edition in February 1988 First printing in February 1988 1.-ncan
288080
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