Filling up with gas

Butane is a saturated hydrocarbon with the chemical formula C4H10. It is odourless and for safety reasons a stenching agent ( mainly ethyl mercaptan) is added to ensure leakages are detected by the distinctive, unpleasant smell.
Butane is 2.08 times heavier than air, meaning it sinks to a low level when released in the atmosphere. For this reason butane cylinders should not be stored below ground and butane fuelled appliances must not be used within cellars or basements.
An expansion ratio of 233:1 means that one volume of liquid butane produces 233 volumes of gas. This cylinder produces enough gas to fill the equivalent of one and a half Olympic swimming pools.
Which is why I thought it best to drive home with the top down.