Some standard content:
Record number: 10075-2002
HG 3250-2001
Chapter 7 of this standard is mandatory, and the rest are recommended
This standard is equivalent to the American Water Treatment Association standard ANSI/AWWAB303:1995 "Sodium Chlorite" to revise the recommended chemical industry standard HG/T3250-1989 "Industrial Sodium Chlorite". The main technical differences between this standard and ANSI/AWWAB303:1995 are: the content of arsenic and sodium nitrate are specified as type inspection items. - Arsenic content is determined by arsenic spot method.
· Sulfuric acid is used as acidifier instead of hydrochloric acid in the determination of sodium chlorite content. - The preparation of the sample is adjusted.
The main technical differences between this standard and HG/T3250-1989 are: ... - Classification and grading are cancelled, and only individual grades are set
According to ANSI/AWWAB303:1995, the content indicators of sodium hydroxide, sodium carbonate, sodium sulfate, sodium nitrate and arsenic are added, and the water content indicator is cancelled. The indicator value is also adjusted according to ANSI/AWWAB303:1995. From the date of implementation, this standard will replace HG/T3250-1989. This standard was proposed by the Policy and Regulations Department of the former State Administration of Petroleum and Chemical Industry. This standard is under the jurisdiction of the Inorganic Chemical Branch of the National Technical Committee for Chemical Standardization. The drafting units of this standard are: Tianjin Chemical Research and Design Institute, Tianjin Sodium Chlorite Plant, Shanghai Xinyu Chemical Plant, Jiangsu Yancheng Huaou Chemical Plant, Jiangsu Xiangshui Hongyuan Chemical Co., Ltd., and Shandong Gaomi Gaoyuan Enterprise Group Electrochemical Plant. The main drafters of this standard are: Yao Jinjuan, Wang Fuli, Shi Genming, Guo Dengyuan, Hong Zhaochun, and Liu Renkun. This standard was first issued in 1989. In 1999, it was transformed from a professional standard to a recommended chemical industry standard and renumbered as HG/T3250-1989.
This standard is entrusted to the Inorganic Chemical Branch of the National Technical Committee for Chemical Standardization for interpretation. 981
1 Scope
Chemical Industry Standard of the People's Republic of China
Industrial Sodium Chlorite
Sodium chlorite for industrial useHG 3250-2001
Replaces HG/T3250-1989
This standard specifies the requirements, test methods, inspection rules, and marking, labeling, packaging, transportation, and storage of industrial sodium chlorite. This standard applies to industrial sodium chlorite. This product is mainly used for water sterilization and the production of nitrogen dioxide. It is also used for bleaching of fibers, fabrics, oils, pulp, etc., and for surface treatment of certain metals. Molecular formula: NaCIO2
Relative molecular mass: 90.44 (according to the 1999 international relative atomic mass) 2 Referenced 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 subtitles. GB 190—1990
GB 191—1990
Dangerous goods packaging marking
Pictorial marking for packaging storage and transportation
GB/T 6011988
GB/T 602—1988
GB/T 603—1988
GB/T 1250---1989
GB/T 6678—1986
GB/T6682—1992
3 Requirements
Preparation of standard solutions for titration analysis (volume analysis) of chemical reagents Chemical reagents
Preparation of standard solutions for impurity determination (neqISO6353-1:1982) Preparation of preparations and products used in chemical reagent test methods (neqISO6353-1:1982) Expression and determination methods of limit values General rules for sampling of chemical products
Specifications and test methods for water used in analytical laboratories (eqvISO3696:1987) 3.1 Appearance: Solid products are white or slightly yellow-green crystalline powder or granules; liquid products are light yellow solutions. 3.2 Industrial sodium chlorite should meet the following requirements: 3.2.1 The mass fraction of sodium chlorite in solid products shall not be less than 78.0%. 3.2.2 The mass fraction of sodium chlorite in liquid products shall not be greater than 50.0%. 3.2.3 Impurity content: Based on the product with a mass fraction of 80% sodium chlorite, the impurity content shall meet the requirements of Table 1. Table 1 Requirements
Mass fraction of sodium chlorate (NaClO)
Mass fraction of sodium hydroxide (NaH2O)
Mass fraction of sodium carbonate (Na2CO3)
Mass fraction of sodium chloride (NaCl)
Mass fraction of sodium sulfate (Na2S04)
Mass fraction of sodium nitrate (NaN04)
Mass fraction of asphalt (As)
Approved by the State Economic and Trade Commission on January 24, 2002 982
Implementation on July 1, 2002
Test method
HG 3250--2001
The reagents and water used in this standard, unless otherwise specified, refer to analytical pure reagents and grade 3 water specified in GB/T6682. The standard titration solution, impurity standard solution, preparation and product used in the test shall be prepared in accordance with the provisions of GB/T601, GB/T602 and GB/T603 unless otherwise specified. Safety Tips: The strong acids and alkalis used in this standard are corrosive. Users should be careful when operating to avoid splashing on the skin. If splashed on the skin, wash with water immediately. In severe cases, treatment should be given immediately. 4.1 Determination of Sodium Chlorite Content
4.1.1 Method Summary
In an acidic medium, sodium chlorite reacts with excess potassium iodide to precipitate iodine. Using starch as an indicator, the precipitated iodine is titrated with sodium thiosulfate standard titration solution to determine the sodium chlorite content. 4.1.2 Reagents and Materials
4.1.2.1 Potassium iodide.
4.1.2.2 Sulfuric Acid Solution: 1+8.
4.1.2.3 Sodium thiosulfate standard titration solution: c(Na2S2O.) is about 0.1 mol/L. 4.1.2.4 Starch indicator: 10g/L, useable for two weeks. 4.1.3 Analysis steps
4.1.3.1 Preparation of test solution A
Weigh sample 1 (accurate to 0.0002g) according to Table 2, place it in a 250mL beaker, add water to dissolve, transfer all into a 500mL volumetric flask, dilute with water to the scale, and shake the hook. This solution is test solution A, used for the determination of sodium chlorite content and sodium chlorate content. Table 2
Sodium chlorite content
Weighing amount/g
4.1.3.2 Determination
Solid sample
5%~10%
10%~20%
Liquid sample
20%~~30%
30%~~~40%
40%~50%
Pipette 25mL test solution A, place it in an iodine volume flask with 2g potassium iodide added in advance, add 20mL sulfuric acid solution, and shake well. Place it in a dark place for 10min. Add 100ml water, titrate the solution with sodium thiosulfate standard titration solution until it turns light yellow, add 1ml starch indicator, and continue titrating until the blue disappears, which is the end point. Perform a blank test at the same time.
4.1.4 Expression of analysis results
The sodium chlorite (NaClOz) content (X,) expressed as mass fraction is calculated according to formula (1): X; (V-Vo)cX0. 2261)
m×500
45. 22(V-Vo)c
×100= 4
Wherein: V-volume of sodium thiosulfate standard titration solution consumed by titrating the test solution, mL; volume of sodium thiosulfate standard titration solution consumed by titrating the blank solution, mL; V
actual concentration of sodium thiosulfate standard titration solution, mol/L; m—mass of the sample in 4.1.3.1, g;
0.02261—mass of sodium chlorite expressed in grams equivalent to 1.00mL sodium thiosulfate standard titration solution Lc (Na2S2O.) = 1.000mol/L].
Instructions for use:
11ANSI/AWWAB303:1995 is 40g of solid, dissolved in a 1L volumetric flask. 983
4.1.5 Allowable difference
HG 3250—2001
The arithmetic mean of the parallel determination results shall be taken as the determination result. The absolute difference of the parallel determination results shall not exceed 0.2%. 4.2 Determination of sodium chlorate content
4.2.1 Method Summary
In a strong acidic medium, the sample solution reacts with potassium bromide to generate elemental bromine, and reacts with potassium iodide in a saturated disodium hydrogen phosphate solution to generate free iodine. Starch is used as an indicator and titrated with a sodium thiosulfate standard titration solution to measure the total amount of sodium chlorite and sodium chlorate. The sodium chlorite content is subtracted from the total amount to obtain the sodium chlorate content.
4.2.2 Reagents and Materials
4.2.2.1 Hydrochloric acid.
4.2.2.2 Potassium iodide.
4.2.2.3 Potassium bromide solution: 50g/L.
4.2.2.4 Saturated disodium hydrogen phosphate solution. wwW.bzxz.Net
4.2.2.5 Sodium thiosulfate standard titration solution: same as 4.1.2.3. 4.2.2.6 Starch indicator: 10g/L, usable period is two weeks. 4.2.3 Instruments and equipment
Microburette: 10ml, graduation value is 0.02ml. or 0.01ml. 4.2.4 Analysis steps
Add 1ml potassium bromide solution and 10ml hydrochloric acid to each of the four 150ml iodine flasks, use a pipette to transfer 5ml of test solution A, add it to the above two iodine flasks, add 5ml water to the other two iodine flasks as blanks, quickly cover the stopper, shake well, place in the dark for 30min, add 0.5g potassium iodide to each, mix and place in the dark for 5min. Add 25ml saturated disodium hydrogen phosphate solution, add water to about 60ml, titrate with sodium thiosulfate standard titration solution until light yellow, add 1ml starch indicator, and continue titrating until the blue disappears. 4.2.5 Expression of analysis results
The sodium chlorate (NaClO:) content (X2) expressed as mass fraction is calculated according to formula (2): X2 =
[(V,-V,)
1Vc×0. 017 74
m×500
177. 4[(V1 - V,) -
Wherein: V, is the volume of sodium thiosulfate standard titration solution consumed in titrating the test solution, mL; V is the volume of sodium thiosulfate standard titration solution consumed in titrating the blank test solution, mL; V is the volume of sodium thiosulfate standard titration solution consumed in titrating the sodium chlorite content, mL., c is the actual concentration of sodium thiosulfate standard titration solution, mol/L; - the mass of the sample in 4.1.3.1, g
0. 017 74-
and 1.00mL sodium thiosulfate standard titration solution [c (Na2S0,) = 1.000mol/L equivalent mass of sodium chlorate expressed in grams.
4.2.6 Allowable difference
Take the arithmetic mean of the parallel determination results as the determination result. The absolute difference of the parallel determination results shall not exceed 0.1% (for liquid samples with a main content of less than 20%, the absolute difference of the parallel determination results shall not exceed 0.05%). 4.3 Determination of sodium hydroxide content
4.3.1 Method summary
The test solution treated with barium chloride is titrated with sulfuric acid standard titration solution to determine the sodium hydroxide content. 4.3.2 Reagents and materials
4.3.2.1 Chlorination solution: 100g/L.
Use phenol anhydride as an indicator and adjust to a slightly reddish color with 1+4 hydrochloric acid solution. 4.3.2.2 Standard sulfuric acid titration solution: c (1/2HzSO) is about 0.1mol/1.984
4.3.2.3 Phenol crisp indicator: 10g/L.
4.3.3 Instruments and equipment
HG 3250—2001
Microburette: 10ml, graduation value is 0.02ml or 0.01ml. 4.3.4 Analysis steps
4.3.4.1 Preparation of test solution B
Weigh the sample according to Table 3 (accurate to 0.0002g), put it in a 250ml beaker, add water to dissolve it, transfer it all to a 250ml volumetric flask, dilute it with water to the scale, and shake it well. This solution is test solution B, which is used to determine the content of sodium hydroxide, sodium carbonate, sodium chloride and sodium sulfate.
Sodium chlorite content
Weighing amount/g
4.3.4.2 Determination
Solid sample
5% ~10%
10%~～~20%
Liquid sample
20% ～30%
30% ~40%
40%～50%
Pipette 20mL of test solution B and place it in a 250ml iodine volumetric flask. Add 5mL of barium chloride solution and immediately cover the stopper to prevent CO in the air from entering the conical flask. Leave it for 3min～5min to ensure that the barium carbonate is completely precipitated. Add 2 drops of phenol indicator and titrate with sulfuric acid standard titration solution until the colorless end point. 4.3.5 Expression of analysis results
The content of sodium hydroxide (NaOH) expressed as mass fraction (X:) is calculated according to formula (3): X = Vc×0. 0400×100 =
m×250
The volume of sulfuric acid standard titration solution consumed by the titration test solution, mL, where: V
The actual concentration of sulfuric acid standard titration solution, mol/L; -The mass of the sample in 4.3.4.1, g;
·(3)
The mass of sodium hydroxide expressed in grams equivalent to 1.00mL sulfuric acid standard titration solution Ec(1/2H2SO4)=1.000mol/L].
4.3.6 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result. The absolute difference of parallel determination results shall not exceed 0.1% (for liquid samples with a main content of less than 20%, the absolute difference of parallel determination results shall not exceed 0.05%). 4.4 Determination of sodium carbonate content
4.4.1 Summary of method
Use sulfuric acid standard titration solution to titrate the sample, and measure the total amount of sodium carbonate and sodium hydroxide. Subtract the content of sodium hydroxide from it to obtain the content of sodium carbonate.
4.4.2 Reagents and materials
4.4.2.1 Sulfuric acid standard titration solution: Same as 4.3.2.2. 4.4.2.2 Phenolphthalein indicator: 10g/L.
4.4.3 Instruments and equipment
Micro burette: 10ml, with a graduation value of 0.02ml. or 0.01ml. 4.4.4 Analysis steps
Use a pipette to transfer 20 mL of test solution B into a 250 mL conical flask, add 2 drops of phenol indicator, and titrate with sulfuric acid standard titration solution until the solution becomes colorless. This solution is reserved as test solution C for the determination of sodium chloride content. 4.4.5 Expression of analysis results
The sodium carbonate (NazCO) content (X) expressed as mass fraction is calculated according to formula (4): 985
HG 3250—2001
X = (Vi-V)cX0 106 0 ×100 =
132. 5(Vi - V)c
m×250
Wherein: V--the volume of sulfuric acid standard titration solution consumed by the sodium hydroxide in the titration test solution in 4.3, mL; V. The volume of sulfuric acid standard titration solution consumed by the titration test solution, mL; - the actual concentration of sulfuric acid standard titration solution, moi/L; m---the mass of the sample in 4.3.4.1, g; (4)
0.1060---the mass of sodium carbonate expressed in grams equivalent to 1.00mL sulfuric acid standard titration solution [c(-H,SO.)=1.000mol/1.1.
4.4.6 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result. The absolute difference of the parallel determination results shall not exceed 0.1% (for liquid samples with a main content of less than 20%, the absolute difference of the parallel determination results shall not exceed 0.05%). 4.5 Determination of sodium chloride content
4.5.1 Method summary
In a neutral medium, with potassium chromate as an indicator, chloride ions react with silver nitrate to form silver chloride precipitate. At the end point, slightly excess silver ions react with potassium chromate to form brick-red silver chromate precipitate to indicate the end point, so as to determine the sodium chloride content. 4.5.2 Reagents and materials
4.5.2.1 Standard silver nitrate titration solution: c (AgNO3)) is about 0.1 mol/L. 4.5.2.2 Potassium chromate solution: 50 g/L.
4.5.3 Analysis steps
Add 10 drops of potassium chromate solution to the retained solution C after the sodium carbonate content is determined, and titrate with standard silver nitrate titration solution until the brick red color just appears, which is the end point.
4.5.4 Expression of analysis results
The sodium chloride (NaCl) content (X.) expressed as mass fraction is calculated according to formula (5): Xs
4 × 100 = 73. 05 ×cV
V c X 0.058 44
m×250
Where: V~-the volume of the standard silver nitrate solution consumed by the titration of the test solution, mL; the actual concentration of the standard silver nitrate solution, mol/L; the mass of the sample in 4.3.4.1, 8;
0.05844—m-the mass of sodium chloride in grams equivalent to 1.00mL of the standard silver nitrate solution Lc (AgNO3) = 1.000mol/L].
4.5.5 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result. The absolute difference of the parallel determination results shall not exceed 0.1%. 4.6 Determination of sodium sulfate content
4.6.1 Summary of the method
The test solution is treated with barium chloride, and the transmittance of the turbid solution is measured at a wavelength of 420nm. 4.6.2 Reagents and Materials
4.6.2.1 Hydrochloric acid.
4.6.2.2 Sodium chloride.
4.6.2.3 Sulfate standard solution: 1 mL of solution contains 1 mg SO4. Weigh 1.48 g of anhydrous sodium sulfate dried to constant weight at 105℃~~110℃ or weigh 1.81 g of potassium sulfate, dissolve in water, transfer to a 1000 mL volumetric flask, and dilute to the mark. 986
4.6.3 Instruments and Equipment
Spectrophotometer: with a 2 cm absorption cell.
4.6.4 Analysis steps
4.6.4.1 Drawing of working curve
HG 3250--2001
Use a pipette to take 0.00 ml, 2.00 ml, 4.00 ml, 6.00 ml, 8.00 ml, and 10.00 ml of sulfate standard solution and place them in a 100 ml volumetric flask. Add water to about 40 ml, add 2.5 g of barium chloride, dilute with water to the scale, and shake well. Use a 2 cm absorption cell to measure the transmittance of the turbid solution at a wavelength of 420 nm. Use the sulfate content as the horizontal axis and the corresponding transmittance as the vertical axis to draw a working curve. 4.6.4.2 Determination
Use a pipette to transfer 5 mL of test solution B into a 250 mL beaker, add 50 mL of water and 5 mL of hydrochloric acid, boil in a fume hood until the solution is clear, cool and place in a 100 mL volumetric flask. Add 2.5 g of barium chloride and mix. Use a 2 cm absorption cell to measure the transmittance at a wavelength of 420 nm. Find the mass of sulfate from the working curve. 4.6.5 Expression of analysis results
The sodium sulfate (NazSO.) content (X.) expressed as mass fraction is calculated according to formula (6): m×1.479
—×100=
m×250
The mass of sodium sulfate found from the working curve, mg; where: m,-
m—the mass of the sample in 4.3.4.1, g;
The coefficient for converting sulfate to sodium sulfate.
4.6.6 Allowable difference
(6)
The arithmetic mean of the parallel determination results shall be taken as the determination result. The absolute difference of the parallel determination results shall not exceed 0.2% (for liquid samples with a main content of less than 20%, the absolute difference of the parallel determination results shall not exceed 0.05%). 4.7 Determination of sodium nitrate content
4.7.1 Summary of the method
The sample is decomposed with sulfuric acid to eliminate the influence of chlorite. In the medium composed of aluminum sulfate, silver sulfate, boric acid and aminosulfonic acid, the nitrate ion selective electrode is used for determination.
4.7.2 Instruments and equipment
4.7.2.1 Potentiometer: The accuracy is 2mV/grid, and the range is -500mL～+500mV. 4.7.2.2 Double junction reference electrode: The inner part is filled with saturated potassium chloride solution, and the outer part is filled with 5.3g/L ammonium sulfate solution. 4.7.2.3 Nitrate ion selective electrode.
4.7.2.4 Electromagnetic stirring: with a PTFE stirring bar. 4.7.3 Reagents and materials
4.7.3.1 Sulfuric acid solution: 1+1.
4.7.3.2 Sodium hydroxide solution: 350g/L. 4.7.3.3 Buffer solution.
Weigh 17.32g aluminium sulfate, 3.43g silver sulfate, 1.28g boric acid, 2.52g aminosulfonic acid, dissolve in 800mL water, adjust pH to 3.0 with 0.10mol/L sodium hydroxide solution, dilute to 1000mL, and store in a brown bottle. 4.7.3.4 Nitrate standard solution: 1mL solution contains 1mgNO3. Weigh 1.63g of potassium nitrate or 1.37g of sodium nitrate at constant weight at 120℃～130℃, dissolve in water, and dilute with water to a 1000mL volumetric flask.
4.7.4 Analysis steps
4.7.4.1 Drawing of working curve
Use a pipette to take 0.10ml., 1.00mL, 10.00mL50.00mL of nitrate standard solution, place in a 100ml. volumetric flask, 987
HG3250—2001
Add 10mI buffer solution, dilute with water to the scale, and shake well. Wash the electrode with water until the potential value is greater than 280mV, and set aside. Pour the prepared nitrate standard solution into a clean and dry 100mI. beaker, place the beaker on an electromagnetic stirrer, add a stirrer, insert the electrode, and measure the potential value of the bath solution under stirring. Read after stabilization for 1min. Draw the working curve with the logarithm of the concentration of nitrate ions (mg/I.) as the abscissa and the corresponding potential value as the ordinate. 4.7.4.2 Determination of the sample
Weigh the sample according to Table 4 (accurate to 0.01g), place it in a 100mL beaker, add a little water to dissolve it, add 10mL sulfuric acid solution, heat it on a water bath until the test solution is colorless, adjust it to neutrality with sodium hydroxide solution (pH test paper test), transfer it to a 100mL volumetric flask, add 10mL buffer solution, dilute it to the scale with water, and shake it well. Wash the electrode with water until the potential value is greater than 280mV, and set it aside. Pour the above test solutions into clean and dry 100ml beakers respectively, place the beaker on an electromagnetic stirrer, add a stirrer, insert the electrode, and measure the potential value of the solution under stirring. Read the value after stabilization for 1min. According to the measured potential value of the test solution, find the logarithm of the corresponding nitrate ion concentration on the working curve, and find the antilogarithm to obtain the nitrate concentration.
Sodium chlorite content
Sample weight/g
Solid sample
4.7.5 Expression of analysis results
5%~10%
10%~20%
Liquid sample
20%~30%
30%40%
The sodium nitrate (NaNO.) content (X,) expressed as mass fraction is calculated according to formula (7): X, = ×100 ×10 ×10 ×1.371 × 100 = 0. 013 71cm
Wherein: c-
Concentration of sodium nitrate found from the working curve, mg/L; mass of sample, g;
m- ---
1.371--Coefficient for converting nitrate to sodium nitrate. 4.7.6 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result. The absolute difference of the parallel determination results shall not exceed 0.02%. 4.8 Determination of arsenic content 1
4.8.1 Summary of method
40%~～50%
Use nitric acid and hydrochloric acid to decompose the sample to eliminate the interference of chlorite. In an acidic solution, use potassium iodide and stannous chloride to reduce pentavalent arsenic to trivalent arsenic. Add zinc particles to react with acid to produce new ecological hydrogen, so that trivalent arsenic is further reduced to arsine. When arsine gas reacts with mercuric bromide test paper, brown-yellow mercury arsenide is produced. Compare with the standard. 4.8.2 Reagents and materials
4.8.2.1 Nitric acid.
Hydrochloric acid.
Arsenic-free zinc.
Potassium iodide solution: 150g/L
Stannoic chloride solution: 400g/L.
4.8.2.6 Arsenic standard solution: 1mL solution contains 0.0001mgAs. Use a pipette to take 1.0mlL of arsenic standard solution prepared according to GB602 and dilute to 1000mL. This solution is prepared before use. Instructions for use:
17ANS1/AWWAB303:1995 adopts atomic absorption method. 988
4.8.2.7 Lead acetate cotton.
4.8.2.8 Mercuric bromide test paper.
4.8.3 Analysis steps
HG 3250--2001
Weigh (1.00±0.01) g of solid sample or the amount of liquid sample calculated according to formula (8) (accurate to 0.01g). Place in an evaporating dish, add 10mL of water to dissolve the sample, add 1mL of nitric acid and 10mL of hydrochloric acid, evaporate to near dryness on a water bath, and be careful not to boil. After adding water to dissolve, transfer to an arsenic determination bottle, add 5mL of hydrochloric acid and 5mL of potassium iodide solution, leave for 2min~3min, add 5mL of stannous chloride solution, leave for 10min, and add water to 40mL. Add 2g of arsenic-free zinc and place in a dark place for 1h. The color of the arsenic spot shall not be darker than the standard. The standard is to transfer 3.00mL of arsenic standard solution, place it in an arsenic determination bottle, and treat it in the same way as the sample. The liquid sample weight m is calculated according to formula (8): 80
Where: X1--the mass fraction of sodium chlorite measured in 4.1, %. 5 Inspection rules
5.1 This standard adopts type inspection and factory inspection. (8)
All eight index items in Table 1 are type inspection items. Under normal production conditions, type inspection shall be carried out at least once every three months. The six indicators of sodium chlorite content, sodium chloride content, sodium hydroxide content, sodium carbonate content, sodium sulfate content and sodium chlorate content are factory inspection items.
5.2 The mass of each batch of products shall not exceed 20t. 5.3 Determine the number of sampling units in accordance with the provisions of GB/T6678. When sampling solid samples, insert the stainless steel sampler to 2/3 of the depth of the material layer for sampling. Divide the sample collected by quartering method and mix it evenly, with a total amount of not less than 500g, and divide it into two clean and dry wide-mouth bottles and seal it. When sampling liquid samples, insert the sampling glass tube to 2/3 of the depth of the container for sampling. Mix the sample collected, with a total amount of not less than 500mL, and divide it into two clean and dry brown bottles and seal it. Stick a label on the bottle, indicating the manufacturer name, product name, batch number, sampling date and name of the sampler. One bottle is used as a laboratory sample, and the other bottle is kept for three months for reference. 5.4 Industrial sodium chlorite shall be inspected by the quality supervision and inspection department of the manufacturer in accordance with the provisions of this standard. The manufacturer shall ensure that each batch of products shipped out of the factory meets the requirements of this standard. 5.5 The user has the right to inspect and accept the industrial sodium chlorite received in accordance with the provisions of this standard. The inspection and acceptance shall be carried out within one month from the date of arrival of the goods.
5.6 If any indicator of the inspection result does not meet the requirements of this standard, re-samples shall be taken from twice the amount of packaging for re-inspection. If even one indicator of the re-inspection result does not meet the requirements of this standard, the entire batch of products shall be unqualified. 5.7 The rounded value comparison method specified in GB/T1250 shall be used to determine whether the inspection result meets the standard. 6 Marking and labeling
6.1 The packaging container of industrial sodium chlorite should be firmly and clearly marked, including the manufacturer's name, address, product name, trademark, net content, batch number or production date, the number of this standard, and the "oxidant" mark specified in GB190 and the "heat-resistant" mark specified in GB191. 6.2 Each batch of industrial sodium chlorite leaving the factory should be accompanied by a quality certificate, including the manufacturer's name, address, product name, trademark, net content, batch number or production date, proof that the product quality complies with this standard and the number of this standard. 7 Packaging, transportation and storage
7.1 Solid samples of industrial sodium chlorite are packaged in iron barrels lined with plastic bags. It is required that there are two layers of plastic bags in the barrel, and the barrel mouth should be airtight and leak-proof. Instructions for use of iron barrels:|| tt||11All items in ANSI/AWWAB303:1995 are factory inspection items. 989
HG3250-2001
The barrel thickness is not less than 0.5mm; liquid samples are packaged in polyvinyl chloride plastic barrels. The net content of each barrel is 25kg, 40kg, 50kg or according to user requirements.
7.2 Industrial sodium chlorite should be covered during transportation to avoid direct sunlight. It should not be mixed with acids and reducing substances. 7.3 Industrial sodium chlorite should be stored in a cool and dry place. It should not be mixed with acids and reducing substances. 7.4 The product has a shelf life of one year from the date of production under the conditions of packaging, transportation and storage in accordance with this standard. If it is overdue, it should be re-inspected to see if it meets the requirements of this standard.
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