A method of supplying a portable medical gas system is provided. The disclosed method includes preparing a portable medical gas system, the portable medical gas system including a cylinder adapted to be filled with medical gas and a gas dispensing valve. The portable medical gas system is place in a specialized container having a configuration adapted to hold the portable medical gas system only when the cylinder of portable medical gas system is unused state or empty state. The portable medical gas system is delivered to the customer, and returned as an empty cylinder via commercial carrier. Upon receipt of the empty or spent portable medical gas system, another portable medical gas system filled with medical gas is sent to the customer. In one embodiment, the portable medical gas system includes a single-use flow control valve which ensures the cylinder is empty after its initial use.