Its often asked if CO2 canisters are allowed on planes and mostly a lot of conflicting information is given in the answers. I recently found the definitive answer so will share it here.
At the time of writing CO2 canisters (max 4 x 28g/50ml per person) are allowed on planes, both in cabin or hold baggage, but prior approval should be sought from the airline and they should be declared at check-in.
I spoke to someone in Dangerous Goods at Qantas and had this clarified to me directly.
I now have a letter from the dangerous goods section at Qantas giving approval to carry up to 4 28g/50ml. Here is a screenshot of the letter so you can see the details & conditions:
Details of how to get this approval are available on many airlines websites.
Qantas Dangerous Goods Information
Emirates Dangerous Goods Information
Other posts you may find interesting:
seeker bikes 