I have always wondered about that, but mine has never self inflated.They make some of them that are manual inflate. They have a plastic T that you have to pull. I have couple of extra canisters for mine, and it has been a little damp. Hmmmm you got me wondering if mine will work now. It just cost 25.00 to find out . I'll take my chances in the water. Another thing I always heard is that it is not counted as a life jacket unless you have it on.