Menhir wrote:
Once you start using the fuel there will be more expansion room anyway, right?
Not necessarily a safer situation though. For liquid/gas fuel tanks like butane lighters, or propane, for any given temperature if there is ANY liquid fuel left in the tank, the pressure inside the container will be the same regardless of how much liquid fuel is inside. It is no safer to have a half-empty fuel can compared to having a full fuel can, of these types.
The types of fuel canister I am talking about are the ones that, when you release the fuel, sometimes cause frost (or at least significant cooling) of the container as it is drawn down. As the gas is taken off the top of the container, the liquid evaporates to make up the pressure. This evaporation causes the liquid part to cool, and sometimes get cold enough to make frost on the outside of the container.
Gasoline and alcohol don't do this.