I'm trying to write a story where a gas leak causes an explosion. How much minimum gas would there need to be for a small shed/small room to ignite when a match is lit in there?
The doors and windows are all shut tight, and the gas has sat in a container with no lid for several days, so it's mostly evaporated into the air.
For example, if I have two gallons of gas that have evaporated into a small shed's room (let's say the width and length of 4 cars squished together) and then light a match, would the room ignite?
If not, how many gallons of gasoline would I need to be present in there?