The Steamboating Forum

barts wrote: ↑Tue Mar 23, 2021 5:15 pm From personal experience - make sure that the propane cannot flow backwards into the steam plumbing, and vice versa.

I installed a spring piston check so that the steam can't get into the propane.

I have two ball valves in line before the steam regulator(bronze), I usually keep them both shut when not in use. What are the risks if some propane started making it toward the boiler? Most of the valves are bronze, I don't think it would last very long in the boiler and I can't identify a potential ignition source.

-CB

cyberbadger wrote: ↑Sun Apr 11, 2021 3:43 pm I have two ball valves in line before the steam regulator(bronze), I usually keep them both shut when not in use. What are the risks if some propane started making it toward the boiler? Most of the valves are bronze, I don't think it would last very long in the boiler and I can't identify a potential ignition source.

If there's propane in the boiler, it will end up via leaks in the bilge. It is unlikely (but by no means impossible) that it will form a flammable/explosive mixture (~ 2%- 10%) in a confined space; the addition of another check valve to prevent this is inexpensive insurance.

I've worked with propane for fire effects at Burning Man. For open air fire effects, it's safer than other fuels - but in confined or enclosed spaces (vehicles), it can be quite dangerous, and unexpected release of propane via venting tanks or plumbing errors lead to unexpected problems. I use a quick disconnect to remove my propane supply from Otter's burner as soon as I can run it on steam, and close tanks valves, etc. Keep in mind that all plumbing handling propane should be schedule 80 (300 psi design pressure) in case of tank overheat.

Wood fires are much simpler; if/when Otter's boiler rusts out I'll likely design another one - all steel this time - with a grate and ashpan I can start on wood. Otter is really too small (19' x 5', 2500 lbs max displacement) to carry enough wood to use as primary fuel. Rainbow (26' x 8', 8500 lb + max disp) is a different matter entirely, we can carry half a cord of fir (1500 lbs) easily - enough to steam for several days.

- Bart

barts wrote: ↑Mon Apr 12, 2021 5:02 pm If there's propane in the boiler, it will end up via leaks in the bilge. It is unlikely (but by no means impossible) that it will form a flammable/explosive mixture (~ 2%- 10%) in a confined space; the addition of another check valve to prevent this is inexpensive insurance.

You can find some confined spaces on my boat, but you have jump in the water and swim underneath and nothing hangs around like it would down below in a typical enclosed boat. I don't have the typical bilge, I have 3 hulls that each have a 3/4" pipe orifice that are normally capped and unaccessible to any of the propane.

Finally a positive for my high windage!

Alright, sorry for high jacking this thread.

-CB