Propane storage

[pmcypress]

Ok I am coming to the experts regarding propane storage. I want to store my 11lb propane tank and a few 1lb cylinders in my rear bumper Aluminess bumper box. Yesterday in SoCal it was about 102 degrees so it was a perfect day to check the temperature in the box. It turns out the inside box temperature was 136 degrees. So my question is can I safely store propane in the box or should I look for another place to store it? Any other ideas?

Thanks

[86Scotty]

I wouldn't worry about it. All propane cylinders have a safety valve. If it decides it needs to vent it will. The smell of propane is put in propane so that you can smell it. It is formulated this way for this purpose. I store propane anywhere including inside and don't worry about it. If it vents I'll smell it. My 5 lb. stove tank has done this exactly once.

You can really overthink and over worry about propane and propane storage. It is a flammable fuel so any place you store it is going to have disadvantages. What if you're rear ended? It could explode. What if you're T-boned in the left side where most RV and SMB propane tanks are mounted? It could explode. And so on.

I'm not trying to blow off the risks of propane, just trying to tell you that there is really no safe place to store it, because it's a flammable fuel. There's also no safe place to store gasoline if you think about it's volatility but we're all sloshing tanks of it around in our vehicles all day every day.

I would keep it in the rear box no matter the ambient temp. Go camping and enjoy!

[pmcypress]

Thanks you are starting to put me at ease.

[arctictraveller]

I would NEVER store a propane tank inside any vehicle's interior. The vapor is more explosive than dynamite in an enclosed area. The inside of the van has multiple ignition sources that could set it off, something as simple as opening the door causing the dome light to come on would do it. At least if it's in the galley box on the bumper there are far fewer ignition sources, although static electricity when opening the door could do it. I'd put it in the box, make sure the box is well vented, (top and bottom as propane is heavier than air and flows down hill like water) and if I smelled propane, I would not open the door, but instead wait until the vapor disapated. A properly installed under body tank that vents to the open air would be best.

Bikini barista dies from injuries suffered in propane explosion | Fox News

[moorefc]

Your standard Sportsmobile bottles are DOT approved, although mounted outside the the frame rails, and are made for the conditions of a vehicle and some level of accidents.....What you are putting in your bumper may not be...As Scotty said above, they should all be vented for overpressure (except maybe the 1# prefilled bottles), but in terms of structure unless DOT approved they are not meant for impact...and where they vent is different.
Just don't get hit, but can you control those behind you? The DOT tanks have a overpressure vent on the bottom designed to vent down and outward. I haven't seen it but if you see an RV fire/accident with either flames shooting out the bottom, or white cloud spray that is the tank venting..
I would think this thru...

[pmcypress]

I plan on only using propane for my Partner steel stove (outside) and an Olympian 3 heater (inside on occasion). May be i should stick with 1lb prefilled bottles? What are your thoughts on storing them in the gear box? I notice they say not to store in temps above 120 degrees.

[arctictraveller]

Originally Posted by moorefc

but in terms of structure unless DOT approved they are not meant for impact...and where they vent is different.
Just don't get hit, but can you control those behind you? I would think this thru...

Propane tanks rarely explode unless involved in a BLEVE (boiling liquid vapor explosion) where an external heat source softens the steel shell and boils the liquid inside. In fact, as the link below explains, it's damn hard to intentionally get one to explode It's the vapor that is so dangerous especially when contained in a confined area. In open air it burns with far less explosive force. If that vapor builds inside the van, any ignition source will cause an explosion if the concentration is between the upper explosion limit (UEL) and the lower explosion limit (LEL). Too few parts per million will not ignite,(too lean a mixture) nor will too many parts per million (too rich a mixture) Since you have to store it somewhere, well vented as possible is best so that explosive mixture can't build up. You can't easily vent the inside of the van in a way that allows the vapor to flow downward. Think about pooring a cup of water on the floor, where will it go? At least if it's in the galley box, if the vapor builds up fast enough to get to an explosive mixture and it finds an ignition source, the door will blow open providing somewhat of a relief valve for the rapidly expanding mixture. How about putting it on the roof?

Propane Tank Explosions, Accidents and BLEVE's

[ShuttlePilot]

Great question pmcypress. This got me thinking because I have some knowledge in liquid propellants. (Disclaimer I don't work for NASA). Propane especially in the 20lb BBQ tanks (and similar sized D.O.T tanks)are everywhere and used by normal folks with little training so they are made with a pretty big safety margin or we would see people blowing up all the time. However, we can find that we can put these tanks in conditions (hot/cold) that will place the tank at the upper end of that safety margin. Here is some proximate numbers found from engineering literature.

BBQ propane tanks minimum burst pressure is around 800 - 900 psi.
Safety relief valves (if working properly) are set around 375psi.
and the fun part
propane vapor pressure at 162* is 375psi
so it could be assumed that at 162* a tank will be venting.
At 130* tank pressure would be 265psi

Now making a decision based only on this assumption in mind is dangerous for a few reasons. It takes only a portion of the liquid pool to reach this temp to increase pressure, the relieve valve opening pressure isn't exact and there is a relationship between the size of the vapor space in the tank and venting. So to make sure people aren't in trouble with these tanks all this should be well above the normal use. i.e. the safety margin. But, I would ask myself how close to the upper limit am I comfortable.

So here is my suggestion.
LPG tanks are painted white to reflect heat. I would keep it white and not place it in a dark container. In fact I would hang it on the back of the van out in the open with a big U.N. class placard 1075 Flammable Gas. That would keep everyone from tailgating. (I'm joking about the placard).
or
I would carry it in the van and take a few measures pertaining to that risk. Maybe make sure its strapped down. Not place it in the sun from a window. Have a propane leak detector I know is working. Make sure I have a normal sense of smell. etc.

Either of these and including as you suggested placing it in the black storage box would probably be fine, however I would chose which one am I most comfortable with. 130* seems a bit more stressful for the tank than I like to do if I have other choices.

I realize this is probably way over thinking it because millions of people use/abuse these tanks everyday with no problems, you just got me thinking about it.
Thanks
-Eric

[pmcypress]

I appreciate all the thoughts. I think I like the idea of storing it up top. I do have a Thule gear box up top. Thoughts on storing 1lb cans up top if i vent the Thule box? I would think the Thuel box would be a lot cooler/safer than the Aluminess box.

[86Scotty]

Originally Posted by pmcypress

I would think the Thuel box would be a lot cooler/safer than the Aluminess box.

I've already learned a lot here, but I saw one thing coming when you first posted. It's happened on this topic more than a few times. Every solution will have it's naysayers. I'm a fan of black Thule/Yakima roof boxes but they get HOT! I mean real hot inside.
I think you are perfectly fine keeping it in the Aluminess box but that's just me.

I'll say again, the info posted here already has taught me a thing or two, but will it change my habits? Probably not. First off I wouldn't leave a tank in a vehicle that hot and mostly I try to avoid ever going anywhere that might happen.

A few years back, when I was a bit more concerned about this, I made a little angle iron rack to store 1 lb. cylinders under my van. Larrie, who bought that van, has the rack and the van now. Maybe if he has it mounted he could post a pic. If not it's buried in my pics somewhere.

I don't want to be the voice of eternal negativity but it's a wonder campers and RVs don't explode more often. They are a house and a car combined, each having several volatile components that get even more volatile when mixed, like running LP fridges, water heaters, etc. while bumping down rough roads or trails. Then there's the fact that we sleep just feet above huge (often full) fuel tanks. Would you build a house with a full fuel tank under your bed? This stuff will keep you up at night, which is why I recommend camping often and always drinking yourself to sleep.

Oh, if you're not disturbed yet then throw a lithium battery in there too, which have blown up many aircraft, yet we still have an undeniable love affair with for their benefits.

I'd love to talk about this more. I'm here to learn to and don't want to sound like a know it all. We could go camping and sit by a campfire and discuss it, 15 feet or so from our LP tanks and our fuel tanks and our batteries.