Welded gas cylinder can be used to fill with low pressure liquid gas such as liquefied propane (propylene), liquefied, ammonia, liquefied chlorine and dissolved gas such as acetylene and etc. The dissolved acetylene gas cylinder of porous solid extender of calcium silicate can be widely used in the departments of cutting, welding, lighting, chemical analysis and military engineering. The products have the advantage of reliable use and safe operation, saving energy, reducing pollution and convenient use and etc.