GB/T 4120.5-1992 Determination of trace water in industrial liquid methyl chloride products - Cloud point method GB/T4120.5-1992 standard download decompression password: www.bzxz.net

UDC661.715.21:543.24
Baojia Standard of the People's Republic of China
GB/T 4120.3-92
GB/T 4120.5-92
Liquid chlorinated methanes for industrial use--Determination of acidity and micro-amounts of waterPublished on April 24, 1992
Implemented on February 1, 1993
National Technical Supervision
National Standard of the People's Republic of China
Determination of micro-amounts of water (cloud point method) in industrial liquid chlorinated methanes;
Cloud point method
Liquid chlorinated methanes for industrial useDetermination of micro-amounts of water (cloud point method) 1 Subject content and scope of application
GB,T 4120. 5 - 92
Replaces GB4120.5--83 bZxz.net
This standard specifies the determination of trace moisture in industrial liquid methyl chloride products. This standard does not apply to products containing alcohol compounds above 0.06%.
2 Reference standards
GB6283 Determination of moisture content in chemical products Karl Fischer method (general method) 3 Principle of the method
The solubility of liquid methyl chloride in water changes with temperature. When the sample is cooled to a certain temperature, it becomes turbid, and the temperature at this time indicates a certain water content of the product.
4 Reagents
4.1 Industrial dry ice (or ice salt solution).
4.2 Industrial ethanol.
5 Instruments
5.1 Colorimetric tube: 25 or 50mL.
5.2 Thermometer: -60～35℃.
5.3 Beaker: 250mL (high type).
5.4 Refrigerated bottle.
6 Analysis steps
The measurement cover is shown in Figure 1.
Approved by the State Administration of Technical Supervision on April 24, 1992 and implemented on February 1, 1993
GB/T4120.5—92
Figure 1 Turbidity point measurement device
1—Thermometer, 2—Cork + 3—Colorimetric tube, 4—Beaker, 5—Ethanol plus dry ice; 6—Sample Add about 20mL of sample to the colorimetric tube, insert the thermometer with cork into the sample, plug the cork tightly, and then place it in In a beaker containing about 150mL of ethanol, slowly add dry ice with a bone spoon, or place the colorimetric tube containing the sample in a beaker containing ice salt solution, so that the sample temperature slowly drops. The temperature drop rate should not exceed 4℃/min, and observe frequently (if the ethanol solution is turbid or there is frost on the outer wall of the colorimetric tube, it is difficult to observe the sample turbidity point. The colorimetric tube can be taken out and the outer wall can be wiped clean with a dry towel for observation). When the sample becomes turbid, read the temperature value immediately, which is the turbidity point of the sample. Take the arithmetic mean of the two readings. Then directly find out the water content (%) of the sample at this temperature from Figure 2.
7 Repeatability
GB/T4120.5--92
Point precision, ℃
Figure 2 Comparison of turbidity method and Karl Fischer method The difference between the results of two parallel measurements shall not be greater than 10%. When the supply and demand parties have disputes over the water content in the product, the GB6283 Karl Fischer method should be used for arbitration. Additional Notes:
This standard was proposed by the Ministry of Chemical Industry of the People's Republic of China and is under the jurisdiction of Beijing Institute of Chemical Industry. This standard was drafted by Chongqing Institute of Chemical Industry. The main drafters of this standard are Xiang Kehua, Xin Benqing, Yu Qingning and Wang Shaoxi.
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