Originally Posted by
TheFlyingCyclist
Interesting. When I started doing this I asked at T5 check in (once) and was told it was fine as long as there were only two of the smaller ones, which is basically what the FAA website above says. Didn’t bother asking again as it seemed like quite a knowledgable answer.
At checkin for BA at BRU yesterday, this came to mind when looking at the quite exhaustive list of forbidden items listed on the counter. CO2 cylinders were specifically enumerated with both the size and quantity limit, as above.