For shipping air, gases or liquids under pressure, NOI, empty. Cylinders from which material has been exhausted will be regarded as empty provided any residue of such material is at a pressure that is insufficient to allow its release. Also applies on empty cylinders containing the residue of hazardous material regulated by the U.S. Department of Transportation only when: 1) the material name, identification number, hazard warning label(s) or placard(s), and any other markings indicating that the material is hazardous have been removed, obliterated or securely covered; and 2) they are excepted from the hazardous materials regulations, per 49 CFR §173.29. Otherwise, the cylinders will be classified as the hazardous material contained therein. Also applies when cylinders have been manifolded and mounted on 4-wheel hand trucks. And Cylinders with projecting valves must have valves protected by a hood, cap or other device that will afford adequate protection from damage. Subject to Item 170 and having a density in pounds per cubic foot of: