A portable gas delivery system for dispensing medical grade gas to a patient, the system comprising: a portable, low pressure gas container comprising an outlet, a pressurized medical grade gas up to 17,27 bar (250 PSI), an internal liquid volume of 0.25 - 1 L, an internal gas volume at 0.5 - 15 L at 13,79 bar to 17,27 bar (200-250 PSI) at room temperature, and a burst pressure of less than 34,47 bar (500 PSI) at room temperature; a low-pressure regulator comprising an inlet and an outlet, and in fluid communication with the container to provide the gas at an adjustable volumetric flow rate from 0-10 L/min and having an inlet pressure up to 17,27 bar (250 PSI) at room temperature; and a two-piece adapter comprising an inner portion removably coupled to and slidably engaged with an outer portion to control a flow of gas between the container and regulator, wherein the inner portion is threadingly engaged to the inlet of the regulator and the outer portion is coupled to the container; and a mask to receive at least one of the patient's mouth and nose removably coupled to the outlet of the regulator, and wherein the container and the regulator each have a weight less than 0,23 kg (0.5 lbs), wherein the system is in an open position when the inner portion of the adapter is in a first position and the system is in a closed position when the inner portion of the adapter is in a second position, and wherein the inner portion of the adapter comprises at least one tab on the outer surface thereof and the outer portion comprises at least one complimentary slot on the inner surface thereof, wherein the at least one tab preferably slidingly engages the at least one complimentary slot to cause gas to flow from the container when turned up to 90° in a first direction from the first position to the second position and reduces the flow of gas from the container when turned in an opposite direction from the second position. a portable, low pressure gas container comprising an outlet, a pressurized medical grade gas up to 17,27 bar (250 PSI), an internal liquid volume of 0.25 - 1 L, an internal gas volume at 0.5 - 15 L at 13,79 bar to 17,27 bar (200-250 PSI) at room temperature, and a burst pressure of less than 34,47 bar (500 PSI) at room temperature; a low-pressure regulator comprising an inlet and an outlet, and in fluid communication with the container to provide the gas at an adjustable volumetric flow rate from 0-10 L/min and having an inlet pressure up to 17,27 bar (250 PSI) at room temperature; and a two-piece adapter comprising an inner portion removably coupled to and slidably engaged with an outer portion to control a flow of gas between the container and regulator, wherein the inner portion is threadingly engaged to the inlet of the regulator and the outer portion is coupled to the container; and a mask to receive at least one of the patient's mouth and nose removably coupled to the outlet of the regulator, and wherein the container and the regulator each have a weight less than 0,23 kg (0.5 lbs), wherein the system is in an open position when the inner portion of the adapter is in a first position and the system is in a closed position when the inner portion of the adapter is in a second position, and wherein the inner portion of the adapter comprises at least one tab on the outer surface thereof and the outer portion comprises at least one complimentary slot on the inner surface thereof, wherein the at least one tab preferably slidingly engages the at least one complimentary slot to cause gas to flow from the container when turned up to 90° in a first direction from the first position to the second position and reduces the flow of gas from the container when turned in an opposite direction from the second position.