Yeah, ammonia can also be used, it's, IIRC, more efficient to use it and a bit safer because you don't high pressure, buuut enough ammonia in the air will suffocate you.
It's lighter than air so it will go away by itself if allowed to. For a purely exterior instalation it's much better than anything else.
It's lighter than air so it will go away by itself if allowed to. For a purely exterior instalation it's much better than anything else.