PackSafe - Small Compressed Gas Cylinders
Small Compressed Gas Cylinders and Cartridges in or with a Device
Carbon dioxide (CO2) and other nonflammable, nontoxic gases. For medical oxygen, see “Medical Oxygen” entry in the PackSafe chart.
Though certain small cylinders are sometimes allowed in carry-on baggage and checked baggage under U.S. and international hazardous materials safety regulations, additional security restrictions must be followed. TSA security rules prohibit the carriage of ALL compressed gas cylinders and cartridges and only allow when empty.
For hazardous materials safety regulations, see 49 CFR 175.10(a)(25)
Small Compressed Gas Cylinders for Mechanical Limbs
Quantity limits: A sufficient number of cylinders/cartridges to ensure an adequate supply for the duration of the journey.
Cylinders/cartridges containing nonflammable, nontoxic gases may be worn in mechanical limbs and spare cylinders/cartridges may be carried in carry-on or checked baggage.
See the regulation: 49 CFR 175.10(a)(12)