Abstract: A gas cylinder refilling system has at least one bar code reader disposed inside the gas refilling chamber and a gas control line for connecting a gas cylinder to a gas source inside the gas refilling chamber, the gas control line having a valve. There is a microprocessor (MPC) connected to a data storage unit, to the bar code reader and to the valve, and being configured to analyze information from the bar code reader such that when the information read by the bar code reader matches stored data in the data storage unit, the microprocessor signals the valve to feed gas to the cylinder.