Some standard content:
GB/T 5138
This standard is equivalent to the Japanese Industrial Standard JIS K1102-59 (reconfirmed in 1988) "Liquid Chlorine", and the chlorine content indicators all exceed JIS K1102-59 (88). The test methods are equivalent to the chlorine content analysis method of JIS K1102-59 (88) and the moisture content analysis method of the international standard ISO2121:72. The comparison between this standard and the Japanese standard and the international standard is shown in the following table: Chapter and article number in this standard
Corresponding international standard
Or foreign standard number
JIS K1102-59 (88)
ISO 2121 --- 72
Determination of chlorine content
Determination of moisture
Test method
Volumetric method
Gravimetric method
Relationship with international standards or
Japanese standards
This standard is a revision of GB/T5138~5139-85 "Industrial liquid chlorine, determination of moisture content by coulometric method" and has deleted GB/T5139.3-85 "Industrial liquid chlorine, determination of moisture content by coulometric method" after revision. According to the requirements of the new situation, the original standard has been modified and is different from the original standard in the following aspects:
1. The original standard is one level, and this standard is divided into three levels. 2. The original standard stipulates that chlorine content and moisture are both factory inspection items, while the new standard stipulates that all items are type inspection items, among which chlorine content is a factory inspection item.
3. Two informative appendices, namely "Determination of nitrogen trichloride content" and "Determination of residue content in liquid chlorine", are added for reference by enterprises and users when needed.
This standard replaces GB5138--85, GB5139.1-85, GB5139.2-85, GB5139.3-85 from the date of entry into force. Appendix A and Appendix B of this standard are both informative appendices. This standard is proposed by the Ministry of Chemical Industry of the People's Republic of China. This standard is technically managed by Jinxi Chemical Research Institute of the Ministry of Chemical Industry. This standard was jointly drafted by Jinxi Chemical Research Institute of the Ministry of Chemical Industry and Electrochemical Plant of Zhejiang Juhua Group Corporation, and relevant units participated in the drafting.
The main drafters of this standard are: Wang Fengtao, Ma Zhanguo, Yang Guoyi, Gao Deliang, Tian Youli, Li Furong, Wang Dehuai. 91
National Standard of the People's Republic of China
Liquid chlorine for industrial use
Liquid chlorine for industrial useGB/T 5138.. 1996
Replaces GB/T51385139-85
This standard specifies the technical requirements, test methods, marking, labeling, packaging, transportation, storage and safety requirements for liquid chlorine for industrial use. This standard applies to liquid chlorine produced by electrolysis, dried and liquefied. Molecular formula: Cl2
Relative molecular mass: 70.91 (according to the 1991 international relative atomic mass) 2 Reference standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T602---88 Preparation of standard solutions for determination of impurities in chemical reagents (negISO) 6353-1: 1982) GB/T603-88 Preparation of preparations and products used in test methods for chemical reagents (neqISO6353-1: 1982) GB/T1250-89 Methods for expressing and determining limit values GB/T6682-92 Specifications and test methods for water used in analytical laboratories (eqvISO3696: 1987) GB11984--89 Chlorine gas safety regulations
3 Requirements
Industrial liquid chlorine should comply with the requirements of Table 1.
Table 1 Technical requirements for industrial liquid chlorine
Chlorine content, % (V/V)
Water content, % (m/m)
4 Sampling
Superior quality
4.1·The daily production quantity is one batch, and at least one cylinder is sampled and analyzed in each batch. Refers to
First-class quality
Qualified quality
4.2 This standard recommends the use of small cylinders for sampling, and also allows direct sampling on large cylinders and pipelines. Whether sampling from cylinders or pipelines, representative liquid chlorine samples should be taken. 4.3 When using small cylinders, after each sampling and measurement, the residual chlorine in the small cylinder should be drained, and the small cylinder should be purged with dry nitrogen at a flow rate of 1000mL/min until there is no chlorine in the cylinder (check with ammonia water), and the small cylinder should be sealed and stored; if used intermittently, it should be cleaned after each use. When cleaning, rinse with water first, then rinse several times with anhydrous alcohol + acetone (1:1), dry and assemble, and store under dry conditions for use. Approved by the State Bureau of Technical Supervision on December 2, 1996, implemented on May 1, 1997. 5 Test methods GB/T 5138—1996 5.1 Common matters The reagents and water used in this standard, unless otherwise specified, refer to analytical reagents and grade 3 water specified in GB/T6682. The full numerical comparison method specified in GB/T1250 is used to determine whether the test results meet the standard. All the test items specified in this standard are type test items, among which the chlorine content is a factory inspection item and should be inspected batch by batch. Under normal production conditions, type inspection shall be carried out at least once a month. If any item fails to meet the standards, double sampling shall be carried out. If any item still fails to meet the standards, the batch of liquid chlorine shall be treated as unqualified products. 5.2 Determination of chlorine content
5.2.1 Method summary
After the liquid chlorine is vaporized, take 100mL of gaseous chlorine sample, absorb the chlorine with potassium iodide solution, measure the residual gas volume, and calculate the volume percentage of chlorine in the vaporized sample. The chemical reaction formula is: 2KI+Cl2=2KCI+I2
5.2.2 Reagents
5.2.2.1 Potassium iodide solution: chemically pure, with a concentration of 100g/L. 5.2.2.2 Sodium hydroxide solution: industrial product, with a concentration of 200g/L. 5.2.2.3 Chlorine-resistant grease: chemically resistant grease based on fluorinated or fluorinated products. 5.2.3 Instrument
5.2.3.1 Gas measuring tube A: capacity 100ml, with 0.05mL graduation on the top. 5.2.3.2 Level bottle F: 250mL capacity, filled with potassium iodide solution (5.2.2.1). 5.2.3.3 Absorption bottle H: 500mL capacity, filled with 300mL sodium hydroxide solution (5.2.2.2), used to absorb chlorine. 5.2.4 Analysis steps
Connect the instrument used as shown in Figure 1. Rotate the valve of the gas burette C to connect the gas burette A to the atmosphere. Rotate the valve of the gas burette B to connect the gas burette A to the level bottle F, and adjust the position of the level bottle F so that the absorbent liquid level is level with the "o" at the lower end of the A tube. At the same time, connect G and absorption bottle H, and rotate the valve B to connect the gas burette to the chlorine source. Slowly open the valve of the steel cylinder to allow chlorine to pass into the gas burette for 2~3 minutes to ensure that the air in the gas burette is completely driven out. Close the valve of the steel cylinder, then close the valves C and B, and remove the absorption bottle H and the connecting pipe for chlorine. Leave it for a while to allow the temperature of the chlorine gas in tube A to reach equilibrium with the outside. Quickly rotate valve C for one circle, gradually raise level bottle F, rotate valve B to allow a small amount of absorbent to flow into gas measuring tube A, close valve B, and allow the chlorine gas to be absorbed by the solution. Repeat this operation until no more chlorine gas is absorbed by the solution, then let it stand and cool for 10 to 15 minutes. Make the liquid levels of gas measuring tube A and level bottle F level, and read the residual gas volume in A.
5.2.5 Expression of analysis results
GB/T 5138-1996
oml line
Figure 1 Diagram of chlorine content determination device
The chlorine content X, (V/V) expressed as volume percentage is calculated according to formula (1): X = (V - V.)/V × 100
Wherein: V-
Sample volume, i.e. the volume of the gas measuring tube, mL; The volume of residual gas in the gas measuring tube, mL. (1)
5.2.6 Allowable difference
The arithmetic mean of the results of two parallel determinations is the chlorine content of the sample. For the same liquid chlorine sample, the absolute value of the difference between the two determination results shall not exceed 0.05%.
5.3 Determination of moisture
5.3.1 Summary of the methodbzxZ.net
The vaporized sample is passed through a weighed phosphorus pentoxide absorption tube to absorb the moisture, and a weighed sodium hydroxide solution is used to absorb the chlorine. Weigh the absorption tube and the absorption bottle separately, and calculate the moisture content of the sample based on the difference between their masses and those before and after the measurement. Chemical reaction formula: P,Os+3H,O-2H,PO4
5.3.2 Reagents
5.3.2.1 Phosphorus pentoxide.
5.3.2.2 Dry air or nitrogen. A convenient way to obtain dry gas is to pass the gas through an absorption tube or drying tower containing a desiccant of phosphorus pentoxide.
5.3.2.3 Sodium hydroxide solution: industrial product, concentration is 200g/L. 5.3.2.4 Fluorine-resistant hose.
5.3.2.5 Chlorine-resistant grease (same as 5.2.2.3). Glass wool or glass wool: use after drying at 110℃ for 1h. 5.3.2.6
Dry absorbent cotton.
5.3.3 Apparatus
GB/T5138—1996
5.3.3.1 Absorption bottle A: contain 1600mL of sodium hydroxide solution (5.3.2.3). 5.3.3.2 Flowmeter B: flow range 500mL/min, use capillary flowmeter with carbon tetrachloride or chlorine-resistant rotor flowmeter. 5.3.3.3 Filter tube C: filled with dried glass wool (5.3.2.6). 5.3.3.4 Absorption tube T, T2: two ground-mouth U-shaped drying tubes with support plugs, filled with glass wool and phosphorus pentoxide in sections, and covered with glass wool at both ends of each tube. In order to ensure the seal, a small amount of chlorine-resistant grease can be applied to the ground mouth at both ends, wiped clean and weighed, each tube shall not exceed 100g. After weighing, mark the ventilation direction and front and back order of each tube, and store it in a desiccator. 5.3.3.5 Small steel cylinder for liquid chlorine sampling.
5.3.3.6 Balance: sensitivity 1g, load 5000g. 5.3.3.7 Safety bottle G.
5.3.3.8 Electric blower with heating.
5.3.4 Analysis steps
5.3.4.1 Take out the absorption tubes T1 and T2 from the dryer, wipe them clean with a lint-free soft cloth, and weigh them with an analytical balance to the nearest 0.0002g. Weigh the absorption bottle containing 1600mL of sodium hydroxide solution (5.3.2.3) with a balance to the nearest 1g. In order to reduce the influence of moisture in the mouth of the cylinder, pass chlorine gas into the unmetered alkali bottle at a flow rate of about 500mL/min for 5min, then wipe the valve mouth of the cylinder with absorbent cotton and dry filter paper in turn, and then quickly connect the instrument according to Figure 2. In order to ensure that the chlorine gas used for the test comes from the liquid phase, the small cylinder can be inverted if necessary. The rubber hose connecting the small cylinder and the absorption tube must be as short as possible, dry and clean, and stored in the dryer when not in use. 5.3.4.2 If it is a newly installed absorption tube, it needs to be pre-treated. If there is no pretreatment, the first result will exceed the correct value. In order to make the impurities in the reagent react with chlorine, first ventilate it in chlorine gas at a flow rate of about 400mL/min for 2h, and then purge it with dry gas at a flow rate of about 400mL/min for 5min. Remove the absorption tube, seal both ends, wipe it clean with a soft cloth, put it in a dryer for 30min, and weigh it. 5.3.4.3 Carefully and slowly open the valve of the cylinder to allow chlorine gas to pass through the absorption tubes T, T2 at a flow rate of about 400mL/min (it can also be controlled to 4 to 5 bubbles/second according to the chlorine bubbles, equivalent to 400mL/min) and then enter the absorption bottle A. Continuously ventilate for 2~~2.5h, and the sampling volume must not be less than 200g.
5.3.4.4 After sampling, close the cylinder valve, use the dry gas heated by the electric blower to blow the absorption tube at a flow rate of about 400mL/min for about 5min, remove the absorption tubes T1 and T2, seal both ends of the absorption tube, wipe them repeatedly with a soft cloth, and put them into the dryer for 30min. Weigh with an analytical balance, and remove the absorption bottle A and weigh with a balance
Dry N2
Figure 2 Moisture determination device diagram
Sodium hydroxide solution
5.3.4.5 If the absorption tube T has obvious weight gain, the absorption tube Ti should be refilled according to (5.3.3.4) and used after pretreatment. When the glass wool has obvious mechanical impurities in the filter tube C or the color turns yellow, it must be replaced. 5.3.5 Expression of analysis results
The moisture content X in liquid chlorine expressed as mass percentage is calculated according to formula (2): X2 = ml/m. X 100
Where: m1—--water mass (i.e., the sum of the mass difference before and after the absorption tubes T and T2 are passed through chlorine), g; (2)
GB/T5138-1996
-sample mass (i.e., the mass difference before and after the absorption bottle A is passed through chlorine), g. 6 Marking, labeling, packaging, transportation, storage 6.1 Marking
Liquid chlorine packaging marking, in addition to the implementation of the provisions of Chapter 2, Articles 11 and 12 of the "Regulations on Safety Supervision of Gas Cylinders", tank trucks and steel cylinders should have obvious "liquid chlorine" and "toxic" words and indicate the vehicle number or bottle number, factory name or address, tare weight and net weight allowed for packaging. 6.2 Labeling
Each batch of liquid chlorine leaving the factory should be accompanied by a quality label of a certain format, including: manufacturer name, trademark, product name and address, net weight, grade, standard number, production date, batch number, net weight, etc. 6.3 Packaging
Liquid chlorine is packaged in tank trucks and steel cylinders. Liquid chlorine packaging volume: steel cylinders shall not exceed 1.25kg/L, tank trucks shall not exceed 1.20kg/L. 6.4 The transportation and storage of liquid chlorine shall be carried out in accordance with GB11984. 7 Safety requirements
Chlorine gas is a Class II (highly hazardous) substance. Even experienced workers are not allowed to work alone and must be supervised. When conducting analysis in the laboratory, the test equipment should be placed in a well-ventilated fume hood. 96
A1 Principle
3—1996
GB/T 5138
Appendix A
(Suggestive Appendix)
Determination of nitrogen trifluoride content
Liquid chlorine is gasified and passed into concentrated hydrochloric acid solution. Nitrogen trichloride is converted into ammonium chloride, which then reacts with Nessler's reagent for color development. The absorbance is measured by a spectrophotometer and the content of nitrogen trichloride is calculated. The chemical reaction formula is: NCl, +4HCl =NH,CI+ 3C12
2K2［Hgl+40H →+NH,+=
A2 Reagents
This method uses deionized water throughout.
A2.1 Hydrochloric acid: analytical grade, 36% (m/m). 0
NH,1 →4K+71-→+3H,O
A2.2 Ammonium standard solution Weigh 0.297g of ammonium chloride dried to constant weight at 105-110℃, dissolve it in water, transfer it into a 1000ml volumetric flask, dilute to the mark, 1 ml. This solution is equivalent to 100 μg of ammonium. A2.3 Sodium hydroxide solution: industrial product, 200g/L. A2.4 Nessler's reagent: prepared according to GB/T603. A2.5 Potassium sodium tartrate solution: 300g/L, prepared with analytical reagents, and treated by heating to remove ammonia. A3 Instruments
A3.1 Gas absorption tube, see Figure A1.
A3.2 20ml stoppered colorimetric tube (special specification). A3.3 Spectrophotometer.
A3.4 Fully enclosed hydrochloric acid separation device, see Figure A2. A3.5 Nitrogen trichloride sampling device, see Figure A3. 97
GB/T5138-1996
10\standard plug
-15# plug
20 mL scale
Figure A Gas absorption tube
10# standard plug
1---Gas absorption tube; 2-Electric heating separation device; 3-Hydrochloric acid collection bottle; 4-Alkali liquid bottle; 5-Air filter bottle (containing 98% sulfuric acid) Figure A2 Fully enclosed hydrochloric acid separation device (schematic diagram) Air pump
A4 Test procedure
A4.1 Drawing of standard curve
GB/T 5138-1996
1--Unmetered alkali solution bottle; 2--Lantong piston; 3--Gas absorption tube; 4--Dark box; 5--Measured alkali solution bottle
Figure A3 Nitrogen trichloride sampling device (schematic diagram) Absorb 0.0, 0.1, 0.2, 0.3, 0.4, 0.5 of ammonium standard solution (A2.2) and add them into 20mL stoppered colorimetric tubes, add 1mL Nessler's reagent respectively, dilute to the scale, and mix well. After 10 minutes, use a 2cm absorption cell at a wavelength of 420nm and adjust to zero with deionized water to measure the absorbance. Use ammonium content (μug) as the horizontal axis and absorbance as the vertical axis to draw a standard curve. A4.2 Sampling
The sampling device is shown in Figure A3. Wipe the sampling valve with filter paper, carefully open the valve, and pass an appropriate amount of chlorine into the unmetered alkali bottle to absorb the chlorine to clean the valve. Install the sampling device, control the chlorine flow rate to 4-5 bubbles/second, sample for about 10 minutes, and calculate the sampling volume based on the weight difference of the alkali absorption bottle before and after sampling.
A4.3 Sample separation
Put the sampled gas absorption tube into a fully enclosed hydrochloric acid separation device to evaporate the hydrochloric acid. A4.4 Determination
Rinse the inner wall of the air inlet pipe of the absorption tube and the outer wall of the part immersed in the hydrochloric acid absorption liquid with deionized water, add 1 drop of 50% potassium sodium tartrate solution, and add 1ml.Nessler's reagent, dilute to scale, mix well. After 10 minutes, measure the absorbance at 420nm wavelength with a 2cm absorption cell in a spectrophotometer, and make a hydrochloric acid blank at the same time. Check the ammonium content of the sample from the standard curve. After deducting the blank, calculate the percentage of nitrogen trichloride in the sample XA (m/m) according to formula (A1):
XA(GX6.67X1.025)/G2X100
Where: G.
-ammonium content of the sample after deducting the blank, g; sample weight, name;
6.67-conversion factor between ammonium and nitrogen trichloride; 1.025-
B1 principle
absorption coefficient.
Appendix B
(Suggested Appendix)
Determination of liquid chlorine residue content
Under low temperature conditions, take about 150mL of liquid chlorine, vaporize and evaporate, and weigh the residue. (A1)
B2 Reagents
B2.1 Powdered dry ice.
B2.2 Anhydrous alcohol: analytical grade.
B2.3 Sodium hydroxide solution: industrial product, 200g/1. B3 Apparatus
GB/T 5138
250mL conical flask with ground stopper and chlorine branch pipe, engraved with 150mL volume scale. B3.1
B3.2800mL beaker.
B3.33000mL alkali absorption bottle.
B3.4 Small watch glass: Cover the conical flask during analysis and weighing before and after the sample evaporates to prevent residue loss and absorption of atmospheric moisture. B4 Test procedure
Before the test, place the 250mL conical flask and small watch glass in an oven at 105-110℃ for 1 hour, cool them in a desiccator for 30 minutes, and then weigh them. At the same time, weigh the weight of the alkali bottle. Install the instrument according to Figure B1, place powdered dry ice around the conical flask, add about 100mL of anhydrous alcohol, cool the conical flask for about 2 minutes (-50℃), slowly open the valve of the cylinder, let about 150ml of chlorine flow into the conical flask in liquid form, turn off the gas source, and let it vaporize naturally in the external environment. Use the alkali bottle to absorb the vaporized chlorine. After the gasification is completed, dry nitrogen with a flow rate of about 250mL/min is passed into the conical flask for about 5 minutes. The small watch glass and the outer wall of the conical flask are carefully wiped with a clean soft cloth, placed in a dryer for 10 minutes, and then weighed. At the same time, the weight of the alkali bottle that absorbs chlorine is weighed. Liquid fluorine
Dry ice + ethanol
Figure B1 Residue determination device diagram
B5 Expression of analysis results
The residue content (XB) in liquid chlorine expressed as mass percentage is calculated according to formula (B1): XB=M/Mz× 100
The mass of the residue in the liquid chlorine (i.e. the mass difference before and after the conical flask), g; where: Mi-—
M2———Liquid chlorine sampling volume (i.e. the mass difference before and after the alkali absorption bottle), g. 100
Sodium hydroxide solution
200g/L
(B1)
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