Amazon: oxygen tank key wrench
Oxygen tank (cylinder) Flow regulator knob T-handle How to use oxygen cylinders 1 Be sure the flow regulator knob is set at zero (see illustration 2). 2 Make sure the T-handle is tight. 3 Place the cylinder wrench on the cylinder’s on/off valve, located at the top of the cylinder. 4 Open the valve by turning it counter-clockwise one full turn.