GB/T 6052-2025Industrial liquid carbon dioxide (English PDF)

4.1 The technical requirements for welding-grade carbon dioxide shall comply with the

specifications in Table 1.

Table 1 -- Technical requirements for welding-grade carbon dioxide

4.2 The technical requirements for industrial carbon dioxide for non-welding purposes

shall comply with the provisions of Table 2.

Table 2 -- Technical requirements for industrial carbon dioxide for non-welding applications

5.1 Batching

Industrial liquid carbon dioxide products filled into gas cylinders via continuous, stable production on the same line constitute a single batch, with each batch not exceeding 500 cylinders. For industrial liquid carbon dioxide filled into gas cylinder bundles, tank trucks, welded insulated cylinders, or spherical tanks, the product quantity within each individual containment unit constitutes a single batch.

5.2 Sampling

Sampling of industrial liquid carbon dioxide shall be carried out in accordance with GB/T 23938.Other requirements shall comply with the provisions of GB/T 43306.

Samples for the determination of all parameters shall be taken from the liquid phase within the packaging container.

5.3 Sample selection

5.3.1 For industrial liquid carbon dioxide packaged in cylinders, random sampling and

inspection shall be conducted in accordance with the sampling quantities specified in Table 3.

Table 3 -- Sampling inspection of industrial liquid carbon dioxide in gas cylinders

5.3.2 Industrial liquid carbon dioxide transported in tank trucks, welded insulated gas

cylinders, spherical tanks, gas cylinder bundle assemblies, or large-volume seamless steel cylinders shall be inspected individually.

5.3.3 For industrial liquid carbon dioxide transported via pipeline, sampling and testing

shall be conducted once every 4 hours, or the sampling frequency shall be determined through consultation between the supplier and the purchaser.

6.1 Determination of carbon dioxide content

6.1.1 Potassium hydroxide absorption method

6.1.1.1 Overview of the method

Absorb carbon dioxide using potassium hydroxide solution. The difference in gas volume before and after absorption represents the carbon dioxide content.

6.1.1.2 Reagents and materials

Potassium hydroxide solution (300 g/L). Weigh 300 g of analytical-grade potassium hydroxide, dissolve in an appropriate amount of water, dilute to 1000 mL, and store in a tightly sealed container for use.

Water. It shall comply with the requirements for Grade 3 water specified in GB/T 6682.

6.1.1.3 Apparatus

For the carbon dioxide content analyzer, all components must be intact, undamaged, and free from leaks. See Annex A for the fabrication diagram.

The volume of the analyzer's absorber is 100.00 mL. The smallest scale division between 98 mL~100 mL is 0.05 mL, and the permissible error is ±0.01 mL.

6.1.1.4 Determination

Open two-way stopcocks A and B. Connect the glass tube at stopcock B to the pressure- reducing valve outlet on the sample container using a rubber hose. Thoroughly purge the analyzer and its connecting lines with a sample gas volume exceeding 1000 mL.

Close stopcock A first, then close stopcock B. Disconnect the rubber hose. Quickly rotate stopcock A several times to equilibrate the internal pressure of the instrument with atmospheric pressure.

Add 105 mL of potassium hydroxide solution to the dropping funnel. Slowly open stopcock A to allow the potassium hydroxide solution to flow into the absorber until the flow ceases, indicating that absorption is complete. Close stopcock A. Read the graduation mark corresponding to the liquid level in the absorber; this indicates the carbon dioxide content.

The average of the readings from two parallel determinations is taken as the result. The difference between the two readings should not exceed 0.05 mL.

6.1.2 Equivalent methods

Other equivalent methods are permitted. In the event of a dispute regarding the test results, the potassium hydroxide absorption method specified in 6.1.1 shall serve as the arbitration method.

6.2 Determination of oxygen content

Testing shall be conducted in accordance with GB/T 6285.Alternatively, testing may be performed in accordance with GB/T 28726, provided that a chromatographic column specifically designed for oxygen-argon separation is used. Other equivalent methods are permitted. However, in the event of a dispute regarding the results, the method specified in GB/T 6285 shall serve as the arbitration method.

6.3 Determination of total sulfur content

Testing shall be conducted in accordance with GB/T 28727.Other equivalent methods are permitted. In the event of a dispute regarding the test results, the method specified in GB/T 28727 shall serve as the arbitration method.

6.4 Determination of moisture content

Testing shall be conducted in accordance with GB/T 5832.1 or GB/T 5832.2.Other equivalent methods are permitted. However, in the event of a dispute regarding the results, the method specified in GB/T 5832.1 shall serve as the arbitration method.

6.5 Determination of total hydrocarbon content

Testing shall be conducted in accordance with GB/T 8984.Examples of the determination are provided in Annex B. Other equivalent methods are permitted.

However, in the event of a dispute regarding the results, the method specified in GB/T 8984 shall serve as the arbitration method.

6.6 Determination of carbon monoxide content

Testing shall be conducted in accordance with GB/T 8984.Examples of the determination are provided in Annex C. Other equivalent methods are permitted;

however, in the event of a dispute regarding the results, the method specified in GB/T 8984 shall serve as the arbitration method.

6.7 Determination of phosphine

6.7.1 Colorimetric method

6.7.1.1 Apparatus

Rotameter. measuring range is 20 mL/min~100 mL/min.

Colorimetric tube. see Figure A.2 for the fabrication diagram.

6.7.1.2 Reagents and materials

Water. shall comply with the specifications for Grade 3 water in GB/T 6682.

Silver nitrate. analytically pure.

Ammonia solution. analytically pure.

Ammoniacal silver nitrate solution. Dissolve 50 g of silver nitrate in 1000 mL of water.

While stirring continuously, add ammonia solution dropwise until a precipitate just begins to form. Allow the mixture to stand, then filter it. Transfer the solution to an amber bottle and store it away from light for future use.

6.7.1.3 Determination procedure

Take two colorimetric tubes, labeled A and B. Add 25 mL of slightly warmed ammoniacal silver nitrate solution and 3 mL of aqueous ammonia to each. Pass 1000 mL of the sample gas through tube A at a flow rate of 60 mL/min~70 mL/min. Then, compare tube A with tube B. The sample is considered acceptable if both remain clear and colorless.

6.7.2 Equivalent methods

Other equivalent methods are permitted. In the event of a dispute regarding the test results, the colorimetric method specified in 6.7.1 shall serve as the arbitration method.

6.8 Determination of oil content

Fit a dry, oil-free, coarse-woven cotton cloth bag over the outlet nozzle of the inverted sample gas cylinder valve (or the bottom outlet pipe of a large packaging container) and secure it tightly. Carefully open the container valve to allow a sufficient amount of carbon dioxide to flow rapidly into the bag. Remove approximately 10 g of solid carbon dioxide from the bag. Place it on a piece of quantitative laboratory filter paper. The sample is considered acceptable if no oil stains remain on the filter paper after the carbon dioxide has sublimated.

6.9 Determination of odor

Carefully open the valve of the packaging container to allow a slow, continuous flow of gas. After 30 s, use your hand to waft the gas toward your nose and smell it. There should be no off-odor.

6.10 Exhaust gas emission and treatment

During the determination, if the exhaust gas contains substances that could pollute the environment, measures for exhaust gas treatment must be implemented.

6.11 Reagent handling

Used reagents should be handled properly to avoid direct discharge into the sewer system. They may be diluted and mixed with a large volume of distilled water, then disposed of in accordance with local regulations.

7.1 Numerical rounding shall be performed in accordance with the rounding value

comparison method specified in GB/T 8170.

7.2 For industrial liquid carbon dioxide supplied in cylinders, the batch is deemed

compliant if the test results for every sampled cylinder meet the technical requirements of this document. If the test results for any single cylinder fail to meet any of the technical requirements of this document, then specific cylinder is deemed non- compliant. A second round of testing is then conducted by randomly sampling double the original number of cylinders from the remainder of the batch. If the results of this second test meet the technical requirements, the entire batch is deemed compliant, with ......