... gas cylinder filling with gas which can be used for keep fresh of fish. 99.5% industrial CO gas and other gas ... , welding, flame processingIndustrial nitrogen ≥99.5GB-T3864-1996CylinderReplacement gas and protection gas for chemical industry, metallurgy ... 99GB/T4842-95CylinderIndustry process, chemical, smelting, protectionPure Nitrogen≥99.996GB/8979-96CylinderChemical industry, glasses, smelting, ...