Warning— this standard hasn't point out any potential safety problems. The users are under the obligation to adopt proper safety and health measures and shall ensure the dissolved acetylene to meet the requirements specified in national relevant regulations.
1 Scope
This standard specifies the requirements, test methods, inspection rules, marks, labels, packages (filling), transportation, storage and safety etc. of dissolved acetylene.
This standard is applicable to the coarse acetylene gas produced by calcium carbide and water action or with natural gas pyrolysis method after it is purified, compressed, dried and ten dissolved into acetone and then stored in the cylinder fully filled with porous aggregate. This product is mainly used as the fuel gas for metal welding, metal cutting and heating.
Molecular formula: C2H2
Relative molecular mass: 26.04 (according to international relative atomic mass in 2001)
2 Normative References
The following documents contain provisions which, through reference in this text, constitute provisions of this standard. For dated reference, subsequent amendments to (excluding correction), or revisions of, any of these publications do not apply. However, all parties coming to an agreement according to this standard are encouraged to study whether the latest edition of these documents is applicable. For undated references, the latest edition of the normative document is applicable to this standard.
GB/T1250 Rules for Expression and Judgement of Limiting Values
GB/T6682 Water for Laboratory Use-Specifications [GB/T 6682-1992, neq IS0 3696: 1987]
GB 7144 Colored Cylinder Mark for Gases
GB 11638 Dissolved Acetylene Cylinders
GB 13591-1992 Rules for the Filling of Dissolved Acetylene
GB 16804 Precautionary Labels for Gas Cylinders
Laoguozi (1993) No. 4 "Specification on Safety Supervision of Dissolved Acetylene Cylinders" by Formerly Ministry of Labor of the People's Republic of China
3 Requirements
3.1 Dissolved acetylene quality shall meet the technical requirements specified in Table 1.
Table 1: Technical Requirements
Item Index
Acetylene volume fraction/% ≥ 98.0
Phosphine and sulfur hydride tests Silver-nitrate test paper doesn't discolor
4 Test Methods
Unless otherwise specified, during analysis, only confirmed analytical reagent and Grade 3 water which meet the requirements stated in GB/T 6682 are used.
4.1 Sample preparation
Cylinder being filled with acetylene gas and after 8h stillness is taken; before sampling, 5% mass of filled acetylene gas is let out; while in those areas where temperature is greater than 28℃, the let out mass of acetylene gas may be properly added but the most shall not be greater than 5% mass of filled acetylene.
4.2 Acetylene purity measuring
Either bromine method or fuming sulfuric acid method, of which bromine method is the arbitration one
4.2.1 Bromine method
4.2.1.1 Method summary
Acetylene is absorbed by the bromine saturated solution of potassium bromide and then generate chemical reaction after which tetrabromoethane is generated. Then acetylene purity is measured according to the volume after bromine saturated solution absorbing.
4.2.1.2 Reagent
4.2.1.2.1 Bromine;
4.2.1.2.2 Potassium bromide solution: 300g/L
4.2.1.2.3 Bromine saturated solution (absorption solution) of potassium bromide: proper amount of potassium bromide solution is taken and put into a ground glass stoppered flask with plug; then bromine is added slowly during which the flask is shaken so as to make the solution to be saturated; then the solution is stilled for one day for standby usage. When the absorbency of absorption solution is poor, the solution must be prepared again.
