Good morning,
I currently keep a handful of nato cans of gas and a couple 20# propane tanks in my garage.  I'm really not comfortable with that since my head board is up against the garage wall...

I plan on getting a plastic shed/ box for the back yard. But in the mean time, how bad would it be stored in an unused car in the yard?

I'm thinking that there wouldn't be enough ventilation.

Also, what are the main requirements for outdoor storage? Just keep them dry with a tarp?
Thanks

Interested in the replies here.  I keep mine in a shed with some fuel treatment in them and have never had an issue.

Propane tanks can leak.  If one does you are dead.  Gas storage should have shelter but high ventilation. Most tanks even say on the label don't store in the garage.

PSA from a real mechanic, (not me) whenever using fuel stabilizers make sure to shake very well after adding and shake very well every month while stored.  The stabilizer will form "finger nail clippings" in the fuel and stop up small jetting or fuel lines.

Tag for info.  I have several types of fuel to store...boat, 2 stroke tools, 4 stroke generator, lawn mower, chainsaw, blower...it’s a lot.

I try to run ethanol free, stock up at the start of summer as the station is far...have to store it.  I add Evinrude 24C stabiliser and Yamaha ring free...no issues yet, but I do wonder about safety.

What are you talking about with the propane?

I don’t like NATO cans, if they aren’t completely full or completely empty it seems like they suffer a lot from condensation. I prefer plastic, yes the cheap plastic cans you get from wherever you get them will die from Uv very quickly.  Get good cans like a VP racing can and you’ll get your use out of it.  

If you have a piece of fiberglass roofing I’d lay that over your cans and bungee or weight it down.

I've never experienced this, are you sure your gaskets were good?

OPD LP tanks have redundant valving. I'm not saying one can't leak but I have personally never seen or heard of one leaking. Have you experienced it?

Well they didn’t leak when strapped to a snowmachine sideways so I assume so

More curious about the part where he says you’re dead if propane leaks.  Mostly because I’ve smelled a lot of propane in my day

I keep my fuel cans in a plastic outdoor storage box, they sit in the side of the house that is shady 24/7.  We actually got the storage box for free, someone left it curbside during bulk pickup trash week. You can get them from Sam's for about $100 though.

OP your temp solution is likely fine.

It’s foolish to store large propane tanks inside a building. The likelihood of an issue is low but the consequences are high so just don’t do it.

I don’t have a problem storing a fair amount of gasoline inside but would generally lean against it if you are using plastic cans....even good ones. NATO cans are GTG and if you buy good ones (no Chinese junk fake NATO cans) you’ll be fine....but it’s never a bad idea to store gas outside a building vs inside.

I have 55gall drums that I rotate fuel through.

They are stored in the shed that's in the shade.

I think the oldest fuel I have is 5 years old and thus far its not been a problem. I use the crap out of the stabilizer.

I'm more concerned about an explosion.
I put them in the driveway last night and threw a tarp over them.

Gasoline Storage Rules

Ethanol Free Gasoline
Stabil
Quality Metal Container with real metal spout (none of that al-gore plastic shit)
Off Ground Storage
Rotate every 3-6 months for best results

Man you have some strict rules for yourself!

My rules that have served me well for years are: airtight container solves all problems that your whole list of rules is intended to bandaid.

I have some gas that has been sealed in a 55 gallon drum for over 4 years now. Prior to that it was stored for 5 years. Only reason I rotated it is because we moved and it's easier to move an empty drum. No problems with the ethanol gas after being stored in an airtight steel drum for 5 years without stabilizers. Plastic storage will work too but it's harder to find reliable, airtight plastic storage.

I chose 55-gal drums for cost/gal storage. 55-gal steel oil drums can be picked up for $0-20 each (a few cents per gallon of capacity). I get mine free. Whereas a 5-gal NATO can etc is $20-60 ($4-12 per gallon capacity). I want to be able to weather a 30 day outage including having transportation so I try to keep 200-300 gallons of gas on-hand. I have 4 drums and 12 NATO cans for gas. I also have a 300-gallon overhead tank of diesel. I have both gas and diesel generators.

It's crucial for gasoline to be stored airtight for long term storage. I want to clarify airtight bc I think you misunderstood what I meant. Airtight (at least to me) doesn't mean void of air, it just means once the lid is put on no air or fuel vapor can enter or exit the confines of the vessel. I fill my drums full to minimize the air volume but you don't want to totally eliminate it bc that allows expansion and contraction of the fuel without rupturing or "ballooning" the vessel.

Now, some will question the validity or safety of storing gas in a drum. Some will say that is a lot of pressure and you shouldn't do that. They're right that it's a lot of pressure. And you definitely should never do it with an open-head drum unless there is also a bung to vent the pressure before opening the head clamp. The type of drum safe for storing fuel is a closed-head drum, the type motor oil etc comes in. Gas, at the most extreme temperature will have a vapor pressure of around 13 psi IIRC. On an open-head drum that means 6,000 lbs of force when you release the clamp, bad things will happen. But most closed-head drums, especially those made for fuels, oils, etc are heavier and can withstand 15+ psi no problem. This is evidenced by the fact that steel drums are used to ship fuels, including gasoline all over the world where normal distribution infrastructure is absent. They load drums of gasoline onto planes and ship them to interior areas of Alaska, they drop them out of airplanes to remote COPs in Afghanistan. And yes, a drum of gasoline in the Afghanistan summer sun will balloon on the ends, but it won't rupture. And the fact that they will hold that pressure enough to make the ends balloon is enough evidence for me to believe that they are airtight.

In regards to plastic, it's not that I don't think plastic can be airtight. It's just harder to find plastic vessel of that size that will hold their shape around the seal area. If the plastic stretches and distorts around the seals it may open up and relieve pressure. My brother used to get me 18-gallon plastic drums that held acid. I rinsed them well and put gas in them. I found that the pressure built by gas was enough to distort the bung around the lid and they would leak. Evidenced by the fact that the fluid level kept dropping despite no liquid leaks. Steel drums won't do that. When I seal one up full and I crack the seal years later it's still full.

And in regards to long term storage, airtight is the key. There are 2 main threats to gas during long term storage. #1 loss of volatile components/compounds. Those compounds are necessary for the gas to properly vaporize, atomize, and burn. If you let them evaporate then your engine isn't going to run right. When people say gas has gone "stale" they often say this bc it smells "stale". It smells "stale" bc the potent, highly volatile compounds have already evaporated off, leaving less volatile compounds that smell different. That different smell is what is associated with "stale" gas. The gas isn't stale at all, it's just not all there anymore so it's chemical makeup has changed. #2 Contamination with water. There are 2 ways for water to contaminate gas, entry into the vessel through liquid (not common) or through vapor. And this is where I think so many have painted ethanol as the devil that it is not. It's no secret that ethanol is hygroscopic (likes water and will bond with it). This is one of the great advantages to ethanol. If you get water in your fuel the ethanol will bond with it instead of floating on top. Fuel foating on top of water is when real problems happen (sucking water into a carb, iced up fuel lines, etc). With ethanol free gas water will not combine and will settle to the bottom of the tank immediately. With ethanol blends water binds with the ethanol and the ethanol holds it in suspension until the amount of water exceeds the ethanol's ability to hold the water in suspension with the gasoline, and it drops out as an ethanol/water mix under the gasoline. People actually use that as a method to remove ethanol from fuel, pour water in until the water overwhelms the ethanol and pulls it out, then skim off the ethanol-free gas from the top. Anyways, I digress. The more common way for water to enter fuel is through a continuous movement of moist air into & out of your vessel. Every time moist air enters the ethanol binds with a minuscule amount of water vapor that contacts the surface of the fuel. If your fuel vessels are exposed to cyclical temperatures the pressure inside will change too. If they aren't airtight negative pressure will draw air in (with water vapor) and positive pressure will expel air. If your vessels are airtight this isn't a concern. #3 Air oxidation of fuels. This problem is such a small concern I don't worry about it but if you limit the amount of air in the vessel and prevent new air from entering it will be a negligible amount of fuel that oxidizes. The oxidizing reaction is the same chemical reaction that happens during combustion, it just happens very slowly in the absence of heat. So imagine a 5-gal can of gas. How much air does an engine have to digest to combust that fuel? A LOT! A fuel can will have to have that same volume of air in it to oxidize that fuel. So the small air void at the top of a sealed can is absolutely zero concern.

In short, an airtight vessel eliminates all concerns with long term storage of fuels. It eliminates water infiltration, it means no appreciable amount of fuel can be oxidized, and it keeps all compounds of the fuel IN THE FUEL.

Large propane "pigs" can be used with conversion. I've seen one set up with a propane feed to pressurize it. Propane and butane are some of the lighter fractions of gasoline.
A pipe known as a wet leg is welded in to the tank in place of the pressure relief valve to dispense gasoline and a valve assembly is installed to allow filling the tank. The setup works well.

The issue is, propane is heavier than air and will accumulate at ground level. This is compounded in an enclosed space. This is the reason for modern building codes requiring propane hot water heaters being elevated at least 18" and have a ground level vent from the room to outdoors. I keeps the pilot from igniting an accumulation of gas.
As for the OPD valve in small tanks, if the leak is small, it won't seal. It really sucks to have one leak when your out camping (in the cold).

What do you mean it won't seal? I've never experienced one that wouldn't. Are you talking about the "slam valve" that closes off if the hose ruptures etc? I'm talking about the safety valve that remains closed until something is attached to the tank. Unlike an old tank that can vent if the valve handle is turned with nothing attached, an OPD tank cannot vent until something is attached.

The "slam valve" (sorry I don't know the proper term) won't close unless there is a significant amount of gas venting. That's not what I'm talking about with redundant valves.

Keep mine in one of the many old derelict trucks out back.
A couple have caps.

I added closets on both sides of my firewood shelter.
Over 100 feet from the house.

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That’s smart and a nice setup. It’s never a bad idea to get flammable fuels away from the house and garage/shop. It’s that ever goes up in flames, it’s gonna burn for a long time with the liquid fuel and solid fuel! But, that’s much easier to survive than your house and/or garage going up in flames.

Are those white things gas can spouts? They look like PVC. More details on them?

Thanks.
Between the 120 gallons of gasoline and 120 pounds of propane, and the 4 to 8 cords of wood, that is quite a conflagration.
Thats why I put the hazmat signs on the closet.

Those are the spouts for the MFCs.
The spouts are inside those cases.
I made them from PVC parts.
The bottom cap slips inside that connector and has a treaded knob ( you can see it on the right one if you zoom in) to keep it together.

IIRC its a 4" to 2" transition, then a 2" to 1.5".  1.5" pipe with a cap and a 4" cap that slips inside the transition.  Might be a 2" to 1" and 1" pipe.
I tapped a hole in the side and used a small threaded knob to secure the bottom.
Makes for a clean way to transport and keeps dirt and spiders out of the spouts.
In practice, I remove the outer case, and after I use the spout, I let it set on the base to evaporate dry and keep it out of the dirt.  Then put it all back together.


This guy did the same thing.

That makes sense and that’s a very cool idea.

I keep my propane tanks in my outside kitchen. I have a couple of metal carports out back and I keep my fuel and diesel in Jerry cans on a rack.

Yes.  
The siding is 1x6, alternated inside and out.  I think I used a ~2" spacing between boards.
So it keeps the rain off the firewood, but allows airflow through it to season it.

The entire floor and base is all PT lumber, built like a deck, with 3/4 spacing between the decking to promote airflow.

So in the closets, for aestetics I kept the same spacing.

Plus any fumes won't build up.

Not a lot of critters.
It's around a foot off the ground.
Something was climbing on the wood stack last year, I found a collapsed section.
Probably a squirrel, maybe a raccoon.

I built the walls with one side of the siding on, then primed two coats and painted two coats, airless sprayer.
Then I primed and painted the other siding and nailed in place.
Used all exterior nails so no corrosion.

The doors are built a little different than the wals, so the boards overlap closer in the horizontal.
The interior 2x4s of the door are on the flat, so the siding is only 1.5" apart instead of 3.5" as in the walls.

Since I didn't use sheathing, I went old school and inlet 1x4s into the stud walls for shear bracing, liquid nails and nails into the studs.  

Construction
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Yes. It is a pressure vessel rated for 225#. Gasoline will never get to that pressure in normal conditions. I'm sure some bureaucrat would have a fit if they found out. In my area you can buy condemned tanks for about a dollar a gallon. (a tank is condemned if it loses the data plate or it becomes unreadable)

One of my favorites

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@Kitties-with-Sigs

Sorry, I just now saw your questions.

The metal caps should have a seal on them. They are very small so easy to miss and sometimes they're in a recess so even more easily missed. I can't imagine a single thing that would be stored or transported in a drum that shouldn't have sealed bungs. For most things you want to keep the contents in, and keep water out. If the bungs don't seal neither will happen. I supposed it's possible some bungs use a tapered thread like pipe fittings and they applied some type of sealant before putting the plug/cap in but every one I've ever seen had a small gasket on it like this picture.



ETA, I should add that they come in many colors. Those found on my oil drums are white and they blend in quite well with the cap. Almost have to be looking for a seal to find it.