Boiling the jug and pouring a bit of hot water on the cylinder seems like it'd be less work than digging out the Wii fit gear, unless of course they use it more regularly rather than just for weighing gas bottles.
How does that tell how much fuel is left?
You pour a bit of boiling water down the side of the cylinder then run your hand down where you poured the water - you will feel a clear delineation in the temperature of the cylinder at the level of the liquid gas inside.
The method described reveals the level of liquid within the container. There is a distinct difference above and below.
Boiling the jug and pouring a bit of hot water on the cylinder seems like it'd be less work than digging out the Wii fit gear, unless of course they use it more regularly rather than just for weighing gas bottles.
How does that tell how much fuel is left?
You pour a bit of boiling water down the side of the cylinder then run your hand down where you poured the water - you will feel a clear delineation in the temperature of the cylinder at the level of the liquid gas inside.
The method described reveals the level of liquid within the container. There is a distinct difference above and below.