Wait air horn "air" is actually butane?
That's... really fucking dangerous especially since most people wouldn't expect air horns to shoot out flammable/potentially explosive gas. Though, butane probably has a lower global warming potential compared to most of the non-flammable refrigerants used in air dusters and such. Takeaway: Use an electronic siren if you need to make noise instead of a canned airhorn.
Well, yes and no. Usually they are filled with 1,1-Difluoroethane, which is heavier than butane, and I believe has a very very low global warming potential.
However, some of them do ship with butane as the propellant, if you look closely.
This one, however, I refilled with butane.
Before anyone says it, yes I understand the risks of refilling canisters, especially off label like this. I've done tons of research and due diligence, taking into account the different vapor pressures and molecular weights of the gases. As well as leaving plenty of safety margin in the headspace in the can. I'm well below the safety margin of the can even when it had difluoroethane in it, let alone the fact that it could handle significantly more.
Have you measured the difference in weight between this and the normal small butane cans? It looks like a neat idea if you're just planning to be on the trail for a night or two.
Even between two people my wife and I won't go through a whole standard can during a weekend trip.
The can weighs 51g full, that's 19g for the can and 32g for the fuel. The can is 37% of the weight of the whole system.
Conversely, the smallest normal canister you can buy weighs 215g full, 102g of which is the can, and 113g is the fuel. The can is 48% of the weight of the whole system.
The savings isn't that much, but it's technically there, and it's interesting. My plan is to bring it on an overnight or two night summer trip to get some laughs from my friends, but I'm not sure I'll use it much more than that.
I'm getting into alcohol stoves too, maybe I'll bring this as a backup? 🤷♂️