GB 8570.3-1988 Determination of residual content of liquid anhydrous ammonia by gravimetric method

This standard specifies the gravimetric method for determining the residual content of liquid anhydrous ammonia (liquid ammonia). This method is applicable to products with a residual content equal to or greater than 0.02% (m/m) as an arbitration method for determining the residual content. GB 8570.3-1988 Determination of the residual content of liquid anhydrous ammonia Gravimetric method GB8570.3-1988 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Liquid anhydrous ammonia
Determination of residue content --- Gravimetric method
Liquefied anhydrous ammonia-- Determination ofresidue content --- Gravimetric methodUDC 661.518bzxz.net
GB 8570.3-88
Replaces GB536-65
This standard equivalently adopts the international standard ISO4276-78 ".Industrial anhydrous ammonia-Determination of evaporation residue-This standard specifies the determination of the residue content of liquid anhydrous ammonia (liquid ammonia) by the gravimetric method. Gravimetric method".
This method is applicable to products with a residue content equal to or greater than 0.02% (m/m) and is an arbitration method for determining the residue content. Note: If the residue content is lower than the lower limit of the determination method of this standard, it is reported as ~0.02% (m/m). 1 Reference Standards
GB601 Preparation Method of Standard Solution of Chemical Reagents GB8570.1 Collection of Laboratory Samples of Liquid Anhydrous Ammonia 2 Principle
After evaporating the liquid ammonia sample at room temperature, weigh the evaporation residue. In the presence of an indicator, titrate the ammonia in the evaporation residue with a standard sulfuric acid solution. Subtract the measured ammonia content from the weighed amount of the evaporation residue to obtain the residue content. 3 Reagents and Solutions
In the analysis, unless otherwise specified, only analytical reagents, distilled water or water of equivalent purity can be used. 3.1 Refrigerant: a mixture of solid carbon dioxide (F ice) and 1 industrial alcohol, with a refrigeration temperature of -35 to -40°C. 3.2 Sulfuric acid (GB625-77): about 10% (m, m) solution. 3.3 Sulfuric acid (GB625-77): c (1/2H2SO4) = 0.1 mol/L (equivalent to 1N) standard solution, prepared and calibrated according to GB601.
3.4 ​​Methyl red (HG 3--958-76): 1g/L 95% (V,V) ethanol solution. 3.5 Silicone grease: for lubricating glass pistons.
4 Instruments
Usual laboratory instruments and:
4.1 Sample sampling device (see figure)
4.1.1 Glass test tube: total volume of about 150ml, with a mark at 100ml, 29-gauge internal standard ground mouth with corresponding external standard ground mouth glass stopper, one of the branches connected to the three-way piston 3, and the other branch connected in series with two 1000ml conical flasks A and B. Therefore, in the assembled instrument, the test tube can be connected to the two three-way pistons 3 and 4, and then connected to the liquid ammonia sampling cylinder and the two conical flasks A and B respectively.
The glass piston is lubricated with silicone grease (3.5), or made of polytetrafluoroethylene. 4.1.2 Dewar flask: used to place test tubes (4.1.1). The markings can be clearly seen after the test tubes are placed. Approved by the Ministry of Chemical Industry of the People's Republic of China on December 2, 1987
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Implementation on September 1, 1988
5 Sampling
Take laboratory samples according to the provisions of GB8570.1. ?
6 Operating procedures
GB8570.3-88
Sample sampling device diagram
1-Sampling cylinder connection; 2.6 Vent; 3, 4-# Ventilation; 5-Connection point,? 1 test tube; 8-Dewar flask; 9-refrigerant: 10-sulfuric acid solution, 11-test tube with stopper 100
6.1 Sample collection
Weigh the mass of two conical flasks A and B, each filled with about 500ml sulfuric acid solution (3.2) and 2 drops of methyl red solution (3.4), and connected with connecting tubes from the connection point 5 (see figure), and weigh to the nearest 0.1g. Weigh the mass of the test tube with cold (4.1.1) (weigh to the nearest 0.0001g). Immerse the test tube in the refrigerant (3.1) in the Dewar flask (4.1.2) to a depth of one-fourth. Remove the stopper and connect conical flasks A and B. Rotate the cold flask 3 to seal the test tube, and let the ends 1 and 2 open to the atmosphere. Use a rubber tube to connect the sampling cylinder with laboratory samples at end 1, carefully open the cylinder valve A, and let ammonia slowly escape into the atmosphere until ends 1 and 2 are well cooled and ammonia droplets appear. Rotate piston 4 to open end 6 to the atmosphere; at this time, immediately rotate piston 3 to close end 2 and connect end 1 to the test tube. Immediately turn piston 4 to connect the test tube and the two conical flasks, and close end 6. In this way, liquid ammonia is collected in the test tube, and ammonia gas is absorbed by the sulfuric acid solution (3.2) in the two conical flasks. When the liquid ammonia in the test tube reaches the 100ml mark, immediately turn piston 4 to open the test tube to the atmosphere, isolate the conical flask, and at the same time rotate piston 3 to close the test tube, allowing ammonia gas to escape into the atmosphere through ends 2. At this point, close the sampling cylinder valve A and remove the cylinder. Take the sample, and then remove the two conical flasks A and B with the connecting tube from the connection point 5. After cooling to room temperature, weigh them to the nearest 0.1g.
6.2 Determination
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GB 8570.3—88
Take out the test tube (4.1.1) containing the sample from the Dewar flask (4.1.2), and let the ammonia evaporate slowly through both ends at room temperature until the bottom of the test tube is t ammonia water, oil and other evaporation residues composed of room temperature non-volatile substances. After the test tube and the evaporation residue reach room temperature, pass a slow flow of dry air (about 100L/h) for 30s. Plug the test tube, wipe the outside with a clean cloth, and weigh it to 0.0001g. Add 50ml of water and 2 drops of methyl red solution (3.4) to the test tube rtl, shake well, and titrate with sulfuric acid standard solution (3.3) until the solution changes from yellow to slightly red.
7 Expression of results
7.1 The residue content X expressed as a percentage by mass is calculated according to formula (1): m2 - m1-m2 × 100
Where: mo
The mass of the sample [the number of milliliters of liquid ammonia collected in the test tube multiplied by 0.68 (0.68g/ml1 is the density of liquid ammonia) and the sum of the mass increments of the two conical flasks and the connecting tubes attached from the connection point 5], g, the mass of the empty stoppered test tube, g;
The mass of the stoppered test tube and the evaporation residue, gThe mass of ammonia in the evaporation residue, g.
After determination by titration, calculate according to formula (2): m3 = Vi × 0.0017
The volume of the desulfurized standard solution (3.3) used for titration, ml. Formula: V-
Note: If the concentration of the sulfuric acid standard solution used is not exactly the same as that specified in this standard, it should be corrected accordingly. 7.2 Allowable error
7.2.1 Take the arithmetic mean of the results of two parallel determinations as the measurement result. 7.2.2 Absolute allowable difference of parallel determination results: Absolute allowable difference, %
Residue content, %
Additional instructions:
This standard is under the jurisdiction of Shanghai Chemical Industry Research Institute of the Ministry of Chemical Industry. This standard was drafted by Shanghai Chemical Industry Research Institute of the Ministry of Chemical Industry and Wujing Chemical Plant. The main drafters of this standard are Yin Yongkang, Jin Zhigen, Yao Bingsheng, Liu Miaode and Zhang Wenwei. Biaosoudu.com
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