The Science of Propane Safety

[Delancey]

According to the leak test gauge on my propane system I've got a leak somewhere. Could be in the propane locker but let's say it's at the connection to the stove or possibly the stove itself and assume it ends up in the bilge.

We have been livingaboard for about six months now and haven't blown ourselves up yet. What happens to the bit of propane that leaks out whenever I valve on and off to use the stove?

Does the propane degrade naturally into it's base elements over time? Does it move from a greater to lesser concentration as a matter of course? Have I not met with disaster because it simply hasn't reached the necessary ratio of fuel to air?

Also, for the extra educated among us, how persistent are the odorants which are added to the propane so we can smell it? Are they also heavier than air and do they remain with the propane once it has settled in the bottom of the bilge? or do they have a shorter life and I could have a bilge full of propane and not know it? Do sniffers sense the propane itself or the odorant?

[Paul L]

You got a leak, find it and fix it!!! The leaking propane will dissipate into the air around it, as long as it is a small amount and does not get any ignition source beforehand. Depending on what side of the solenoid valve the pressure gauge is on, it is pretty straight forward to determine if the leak is between the tank and value or between the valve and the appliances. Divide and conquer,

[Outwest34au]

Hi,
get a spray bottle with some water and dishwashing detergent mixed and spray around every joint you can find and on crimped hose ends. It will show a stream of bubbles for even a minute leak.
LPG is a wonderful thing and very safe compared to other fuels BUT can also blow you to a lot of little bits if things go wrong. Things that could go wrong include a bilge full of cool condensed vapour waiting for an ignition source.
PLEASE tend to this immediately.

[barnakiel]

I will disconnect the hose at the stove and plug it. Then re-test. If the leak is still there, I go along the hose with a wet sponge / dishwash till I find the leak.

If the leak is within the stove sometimes the oven has to be opened up. This is sometimes an issue as most of them are riveted together.

b.

[Delancey]

Thanks to all, not really looking for info about finding a leak. Just on the science of propane itself. For the sake of this thread let's just assume the leak is in the 28 year old stove I can't repair and don't have money to replace right now.

So you leak a little fuel every now and again, then what? It breaks down? Moves from greater to lesser? What about the odorant? As before this is not a new issue and we have been living aboard for six months. I don't have a death wish but it obviously hasn't been a safety concern so far.

[Delancey]

Link to Yachting Monthly's crash test boat, yes I understand the hazard.

Yachting Monthly's Crash Test Boat - Explosion! - YouTube

[barnakiel]

For the science of propane itself, it will accumulate and then your boat will explode and kill whoever happened onboard. There will be some damage to adjacent installations too that your insurance will refuse to pay as you knew about the leak and you did not fix it.

b.

[Delancey]

It's been six months, how long will it take before I blow up?

[Morgan3820]

I would add a little glycerin to the soap. Helps keep the bubbles from collapsing

[Nemo55]

Propane is heavier than air,,it will seek the lowest point in your vessel,,,,super important to ventilate your bilges and engine spaces,,,,given enough air circulation it will dissipate and render itself safe to be around.
Think of it this way,,you could be standing in a pool of propane gas,,and light a fire at chest level and it would not combust,,,but if any of that propane gas is disturbed enough to rise to the level of the ignition source,,,
KABOOM !!!
Other than that,,Propane is safer than most other fuels,,,it will act very much like the flame from a cigarette lighter if ignited close to the leak,,,starve it for oxygen and it is intrinsically safe once more.

This is why i do not like storage of propane below decks,,,,it has a nasty habit of gathering,,,

[Kettlewell]

No leaks allowed! Find the source, and don't use until it is fixed. Get the set up with a solenoid valve that installs right next to the tank in the propane locker so you can just flip a switch and the propane is turned off after cooking.

[Delancey]

Regarding solenoids, ours died shortly after purchase of the boat. I haven't replaced it because it seems like another gadget likely to fail and instead prefer to be strict about valving off after use. Who knows, maybe the red indicator light fails, you think you are safe but are not. ABYC does not require a solenoid, anyone else prefer piece of mind over convenience?

[sailvayu]

Originally Posted by Delancy

It's been six months, how long will it take before I blow up?

Any day now I would suspect or it could be another six months, you must be a gambler

[Kettlewell]

My current solenoid is now about 7 years old--they are pretty basic devices. Much more reliable than a lot of things onboard. When I flip the switch I can hear it turn on, and the little light comes on. As soon as I am done cooking I flip it off. Yes, the light could potentially fail, but I also have my hearing and the switch is mounted at eye level where I can see it from the salon and it is right next to other gauges and things I check frequently. I can tell by the position of the switch if it is on. So, yes, there is always a potential for failure, but I am more likely to flip the switch to off than I am to leave the cabin and go out to the propane locker to turn the valve before and after every cooking session. I do turn it off at the tank valve if I am leaving the boat for a longer period of time, but I also flip the main power off when leaving and that also would close down the propane solenoid.

[sailvayu]

Originally Posted by Delancy

Regarding solenoids, ours died shortly after purchase of the boat. I haven't replaced it because it seems like another gadget likely to fail and instead prefer to be strict about valving off after use. Who knows, maybe the red indicator light fails, you think you are safe but are not. ABYC does not require a solenoid, anyone else prefer piece of mind over convenience?

ABYC does require a solenoid and so does the USCG for that matter. It is a gadget designed to save lives not annoy boat owners.