Oxygen cylinders are seamless steel containers holding about 244 cubic feet of oxygen at a pressure of 2200 psi at 70 degrees F. A smaller cylinder holding about 122 cubic feet is also available. A typical oxygen cylinder is approximately 9 inches in outside diameter, 54 inches in height,and between 104 and 139 pounds in weight(empty). The difference in weight depends on the type of steel used to construct the cylinder. A full cylinder will increase the weight by about 20 pounds. The oxygen supplied through these cylinders is about 99.5 percent pure. The oxygen pressure will vary according to temperature changes, but the weight and percentage of oxygen remain the same.