Propane Cylinder Level Indicator?

Hi Everyone,

First post here. I've only just started with Arduino but already I am hooked. I've searched the forums and google and I cannot seem to find anything that would help me with this particular project.

Some background:

I live on a boat on the internal waterways of the UK and as such live "off-grid". My power comes from a leisure battery bank which is kept charged either from my engine's alternator or from 350w of solar panels on my roof.

To heat water (shower's etc) and to cook I rely on two 19kg propane cylinders which are stored in a separate gas locker at the front of my boat.

I am looking for a way to measure the amount of gas left in these bottles - they last for a few months each but if they run out it's cold showers and cold food all round...

My first thought was to weigh the bottles to determine the amount of propane left in there; the issue is that my gas locker is known as a "wet locker" and therefore has about 6" of water in the bottom of it. This and the fact that the gas bottles can move around inside the locker at times when the boat is on the move put me off this idea - I think it would be too inaccurate and tricky to install.

I also thought about measuring the temperature of the bottle to determine the level at pre-determined points along it's length, but due to the fact that the bottom of the bottle is submersed that is also not an easy option. In addition to this, the bottles are exchanged rather than refilled, they are not a permanent install; making alterations to the tank, or attaching something that is not easily removed is not really an option either.

I do not need anything particularly accurate, a simple "Full, 3/4, 1/2..." type gauge would do.

Any ideas?

All the Best,

James

Surely if the bottles are in water they will corrode, and if they can move around the valve/hoses could be damaged? I'd think about curing these issues too - a frame you can clamp the bottle to with load-cells at the (weighted) base could be one approach.

Put them in some kind of slatted cage to restrain their sideways motion and hang them from fish scales. Make one of the slats easily removable(stainless steel studs and wing nuts) so as to replace tanks. Four vertical members should be enough with one removable.

So you have both bottles connected? I had only one connected, and when it ran out I connected the other one. Time enough to have the empty one refilled. Fancy things don't work on a boat. Leo..

Fancy things don’t work on a boat.

For very long, anyway.

JamesMW: I rely on two 19kg propane cylinders .......they last for a few months each.......my gas locker is known as a "wet locker" and therefore has about 6" of water in the bottom of it. This and the fact that the gas bottles can move around inside the locker at times when the boat is on the move

If you haven't already blown yourself up, along with some of the neighbourhood, you might consider using gas fuses just like most everybody else does. Then, when you see the pointer in the red refill zone, guess what? It's probably time to refill. And who knows? you might find that you can kid your insurance company that you have been using them all along.

If you find that too radical an idea, then using one bottle at a time, as Wawa suggests, is a very reasonable solution.

Caravans and bottle gas homes have a changeover tap and only one bottle connected at a time.

Weedpharma

Use an electric bilge pump so they don't float. Dwight