Do rebreather cylinders need to be empty for air travel?
Yes. For air transport, pressure cylinders should be empty with valves removed so security can inspect the interior.
Yes! Airline regulations require that all transported pressure cylinders must be empty with valves removed. Place the valves in clean PE bags (Ziploc) and place tape over the neck to prevent contamination. It is possible that security personnel will want to look inside the cylinders. Therefore it is not appropriate to use tight plugs that cannot be removed without tools.