Full to the bottom of the neck is fine. Got lots of them in that condition here. Filled at 50 ambient temp, and have been up to 100 amb temp several times. They are fine.

I'm seeing people say the more gas you get in the can, the less it will bulge.

I think that is wrong.

The vapor pressure of the gas in your can is the same regardless of how much gas is in it.
The primary influence is temperature.  

When the system equalizes, the tank should feel the same pressure whether an inch from full or an inch from empty.

Exactly the same reason why a pressure gauge is worthless for determining a BBQ grille tank level.

All we need is for some dope to fill his gas can 100% full in the winter, then store it in his garage that gets 130F in the summer.
Recipe for disaster.

Umm, yeah.  So wonder what's going to happen.  I guess I should move my cans away from my hot water heater.  

Oh holy crap, I didn't read the entire thread, and didn't see that.

Depending on the size of the dent, it might be perfectly safe.
But with MY luck, I'd split the seams and spill all the gas on the floor.

Guys,

A full fuel can will have less stress than a fuel can that is less than full.  

The liquid gasoline is not the source of the force that stresses the can.  Here is a fun fact use for the consistent density of gasoline.  http://en.wikipedia.org/wiki/Bathyscaphe_Trieste

Air and gas vapor in the can make the force that pressurizes the can and stresses the can.  In US units we measure this in psi = pounds of force per square inch of area.

Think about a Scepter MFC 18 X 14 X 6 inches with an air chamber at the top  for flotation (this was the original purpose of that air chamber in 1939) and a the threaded filler neck. For the sake of calculation:  I am going to say the air chamber has a surface area of 84 square inches (three sides of 6 x 4 and two end triangles with 4 inch sides).  The filler neck is a 2 inch diameter cylinder about 3 inches tall, so the filler neck has a surface area of about 25 square inches.

Fill the can up so that only the filler neck and float have air.  Do this in Jan in Northern MN then take the can to Death Valley the first week in Aug.  I cannot think of much more extreme winter to summer differential than that .  Now say by some magic we measure the pressure in the can to be 15 psi.  

(15 psi X 84 insq) + (15psi X 25 insq) = 1260 pounds force + 375 pounds force = 1635 pounds of force

NOW leave a little room for expansion like the internet commandos like to brag about.  Just lowering the gas away from the top of the can adds another 144 square inches of area to be pressurized.  Which would add another 2160 pounds of force on the can for the Death Valley trip.

Ok now get really clever and outsmart the interweb commandos and leave plenty or room for expansion.  You will get to post epic pics of gas can balloons.  Each inch that the liquid level of the gas is lowered will add another 40 square inches of area to pressurize.  That is another 600 pounds of force on the can for the Death Valley trip.

So the trip summary:
Full can 1635 pounds force
Can with a little room for expansion 3795 pounds force
Can with an inch for expansion 4395 pounds force
Can half empty 9195 pounds force

In all these conditions the gas pressure of the can is 15 psi.
So yes a pressure gauge gives no indication of how much liquid is in a tank, but any tank that is not full will be under greater stress.


TLDR
Full can has less than half the force on it as a can that is not full.

33



Yes

The example I gave above is all 15psi.  The deal is that the liquid gasoline does not change pressure.  The liquid just transfers pressure.  It is the air and gasoline vapor at the top of the can that is free to change pressure.  When there is more room at the top of the can there is more surface area for the vapor to push on.  

Another example:  223WSSM vs 243WSSM.  The cases only differ in neck diameter, and the chamber pressures are close.  The larger diameter 243WSSM yields higher muzzle velocities because the 243cal diameter gives a larger area for the gas pressure to push on.



Yes if the fuel storage container is vented, then it is practically an open bucket.

From page one of this thread http://www.ar15.com/forums/t_10_17/643480_FUEL_CAN_ORACLE.html&page=1#i10967550

PA, I think you need to reanalize the physics of this...  

It makes absolutely no sense to me, not that's a big deal or nuthin...

Well, this interweb commando claims the pressure created inside the can due to the vapor pressure of the gasoline is felt by the entire can equally, not just the part above liquid level.  The vapor pressure exerted on the surface of the liquid gasoline is transferred hydraulically to everything below the surface.

Another point to make is that unless the lid on the gas can is capable of holding the vapor pressure of gasoline at the highest temperature the gas can might experience, your gas can will eventually become empty.  
It might take years, but you will lose gas through evaporation.
As the vapors escape, more vapors are created to replace them.  It is a never ending process until no liquid is left.
Periodically venting your gas can to relieve pressure is a waste of time and fuel, as the pressure will always come back.  

I had a few plastic 5-gallon gas cans filled to the full line.
Stored in my garage for 5 years.
In the summer, I always smelled a little gas in the garage.
I never cared.  I knew it was either the gas cans or the car.
On the really hot days the smell was pretty strong.
Just before this winter I used the gas in those cans after putting a new gas tank on my pickup.
Every gas can was about a gallon lower than when they were full.
(truck is an '85 F150 L6, and doesn't much care what kind of gas I feed it)

You could throw a brick in a MFC, or fill it half way with gravel, or leave an airspace or a dent, or add air, and the only thing that would affect the internal pressure, given ANY residual qty of liquid gasoline, is temperature [that determines the gasoline vapor pressure].

Internal VAPOR pressure has NOTHING to do with airspace, can shape, or volume occupied by other non-volatile material.

Period.

[Except if the can is filled clean to the tippy top and closed. Then the Filler will learn about the properties of expansion, with increasing temperature, of a liquid]

It great to be a Internet Gasoline Commando! Who barely passed phsicks class!

Anyone know if these cans are gtg?

Sportsman's Guide Jerry Cans

$26.99 per 20L can and SG has a free shipping coupon good for today: SH184

stay away from the chinese made ones unless you wsnt them for display only....

Thanks! kinda figured that.  Guess I'll order more of the DO cans.

I have a better example.

For the sake of argument, lets say we have a sealed container that measures 12x12x24" high.
It is half full of water.  (12" depth)
A pressure gauge at the very bottom of the tank will read 0.433 psi, due to the weight of the water.  (head pressure)

Now, I hook my air compressor to a valve at the top of the tank, and charge it with 100psi.

Do you believe the pressure gauge at the bottom of the tank reads near 0.433, or near 100 psi?

Obviously you would agree the pressure gauge will read near 100 psi.

Which should prove to you that the air above the liquid is exerting 100 psi on all surfaces equally, whether directly on the container surface, or through the liquid.  

The volume of headspace above the gasoline has no impact on the pressure the tank will experience due to vapor pressure.

But what happens if you place the can on a treadmill???












Sorry for the temporary diversion, I couldn't help it.   I thank you guys for discussions like this, it's fun to read.

But what happens if you place the can on a treadmill???

I posted most of this info some time ago but wanted to post in here to help others. I also up dated some of my finding.  

So before I found real NATO cans I was at a Fleet Farm store and found some of the "NEW" NATO metal cans with the stupid "NEW" CARB caps that just plane suck. I wanted something that I can store and not leak all over the place. So I did a lot of looking and came up with some WEDCO transport caps. This is a cap without any spout hole and was ment for transporting fuel only. It has a rubber gasket to help keep a tight seal. I did have to cut off the small tether holes on the cap to get past the child safety bump on the can. They did not work on the newer plastic cans but if I trimed the base some I could make them work.

Orginal caps are junk.

I got them for this seller on E-bay.  I am not the seller  Link to Ebay seller.













I had to trim a few caps to get them to fit some of my cans.  They would not seal tight before the trim but now its air tight.

I will ask My Hydraulics/pneumatics prof if its better to be full or not so full.

Oh boy! In!

If he has a phd it might be even better!

I asked a friend of mine who has a masters degree in physics.
She was pretty sure a can with less fuel would bulge more.

The reason I asked is because while thinking through the problem, you can fool yourself.
And I knew she would fall into the trap.
I asked her just to have a little fun with her.

An advanced degree only means you are more knowledgeable about one specific topic within the subject.
She focused on superconductivity...  which doesn't exactly provide more education on basic concepts of physics.
(I have a BS in physics from the same school she graduated from, so I am qualified to make that statement)

I bet a dozen engineers would argue amongst themselves before settling on one answer.

I employed every walk of life, ---from off the street and gave them an opportunity [most were GREAT! and most really appreciated the opportunity and were successful] ---to BS and advanced degrees incl folks w/ a PhD in nukeler physics [for all you nkuler pronunciation aficionados    ] and...

...the more advanced the degree the more you sort of [figuratively] had to help them inside when it started to rain.

Like you say though they were great in their respective fields, the guys I hired were super. I just had to manage them carefully for them to be productive for my objectives --and I'd have to say they required more management the more advanced the degree, and that's understandable.

As far as having great amounts of common sense, the more advanced, I'd have to say the less common sense.

On the other hand, I think the more advanced, their EGOS increased exponentially.  

All being said, they were a very creative and productive bunch of guys and gals and I often miss having them to work with.  

One guy who had an advanced degree [math and physics IIRC] had been working for a Fortune 500 co and for some reason wound up not working there and took a job at a computer store. I ran an ad for a uproc programmer and he responded and I hired him. During my due diligence I called the owner of the computer store to check his reference and talking w/ her I asked why they were only paying him abt min wage.

She said that's "all he was worth"!  

I'm here to tell you that with logical supervision and management he was worth a million dollars to me. I can't begin to explain his ability he had to program those things and the complex functionalities he wrote to support our products. He stayed with me many years until after I sold the co and then the new owners apparently couldn't manage him to be productive and fired him.

[I think new owner's of companies egos and stupidity exceed most every other class of folks, but that's another story.]

He used to forget and let his lights on in his vehicle and was late for work and said he couldn't charge his car until he completely dishcharged his battery by keeping his lights on till the battery was dead!

We used to argue the science abt that with him but he never changed his mind.  

Anyhoo, I think asking a [Hi IQ Idiot, certainly not ALL are...] about how a MFC should be filled and the underlying science, should be a real fun eye-opener.

I store gas cans in 120+ degree temps for a year with no problems.



Initially I did not use a stabilizer, but now I do so they should be good for a very long time.
 

Does anyone know where I can find a USGI  gas can spout?  I gather they are hard to find.

My dad's 1965 Impala was stored in a garage he was renting all throughout my childhood.
After 20 years or more we moved, and needed to bring the car with us.
Brakes seized, clutch seized, it was a mess.
With a new battery, the engine cranked over, but wouldn't fire.

He dribbled gas into the carb and it started right up.
And continued to run.
After getting things un-stuck, he drove it to the gas station and got fresh gas.
Point is, OLD gas that wasn't in a perfect container still seemed to burn in a carbureted engine.
Maybe not great, but it ran okay.

Exactly.

20 year old gas probably has a different chemical makeup than the gas of today and it certainly didn't have ethanol in it back then so I'm going to have to say apples and oranges.

That said I do believe one can get a couple years out of untreated gas stored in an airtight container (as several posts here attest to), but I still use PRI-G for long term storage. I just tried a can I filled in June '09 with PRI-G and I didn't have any problems with it. I have three more from June '09 that I'll try each upcoming year.

After reading every page (all 29) on this post, I've ordered four 20 Liter cans from Oldgrouch. I'll be taking them on a week long Boy Scout camp this summer.

Guys,

I have several of the Blitz style cans and I'd like to get at least one nozzle.

Compression style

or

The threaded "aftermarket" one pictured on page one of this thread.

Please forgive me, but I didn't feel like looking through all 29 pages of the thread....

Anyone know where I can get at least one of these nozzles for my Blitz style 5 gal fuel cans?

Make you own

Instructions are posted on page one and page two of this thread.

You will probably need to do this,
unless you can find one at a surplus store or garage sale, etc.

Something on this site may be of use.  Never used them.
http://ezpourspout.com/wp/ez-pour-products/

or these?
http://rotopax.com/Conventional-Spout-Set.html



I just gave up on spouts and use funnels w/ long either curved or flexible necks.

http://www.amazon.com/Plews-75-007-Utility-Funnel-Filler/dp/B000NCWV2U/ref=sr_1_3?s=automotive&ie=UTF8&qid=1372461495&sr=1-3&keywords=funnel+flexible

http://www.amazon.com/gp/product/B003C018CY/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1

with the recommended funnel.

I received my 4 pack of red Jerry cans from Oldgrouch. These things are awesome. Shiny, no dents whatsoever, brand new. The gaskets are new and very tight. An all metal spout was included. Looking inside, the lining is new.





















 

OldGrouch is probably the only source I would buy from at this point.  

I have a question guys.  I got some used MFCs.  One of them has a gouge 3/4 of the way up the side.  It didn't look deep enough to be a hole, but when I filled it, the side of the can started to get darker.  I couldn't see any drips, but it is obviously leaking out.   What's the best way to patch this, from the inside or outside?

Matt

Plastic Scepter MFCs are made of high density polyethylene. Polyethylene does not bond well with most adhesives, so I do not konw of any patch that would work

There are some plastic welding methors that might work, but you might be able to drive to Canada and buy a new can for less money.

I recently bought some cans from AB.  The cans are awesome and work better than anything I've ever had.  The venting of the spout and can means liquid comes out RIGHT NOW!  I highly recommend them and I'm thinking about getting some more in the future even though I don't really need them!

Thanks to a thread on Arf that reminded me to check CL, I scored these today:

Their cans and spouts are on sale through September 2nd.

http://www.roverparts.com/nxt/?keywords=jerry+cans

If it's leaking, you'll smell the vapor, as a small leak will allow the fuel to vaporize instantly.

Smell, cover with Saran wrap, and concentrate the area at the gouge.

There is a possibility to 'plastic weld' the gouge or mechanically attach a patch, but the effort prolly isn't worth the $80 bucks to buy a brand spakin new tank off ebay.

If no leak is detectable, enjoy the can.

just ordered 3 for my dad as a gift and 1 to keep from lexington container, I'll post pics and confirm they are the real deal when they come in.

Just received the case of cans from lexington supply and they are the real thing.



The cans are Wavian and are marked with the un certification #

(U over N symbol)   3A1 /  Y /  100 / 13 / D / BAM6210-VP

3 = Jerricans
A = Steel
1 = Closedhead

Y = Packaging Group II and III    Packaging Group II: Medium Danger - medium hazard level

100 = Hydraulic pressure in kilo-pascal (kPa)

13= year of manufacture

D=????

BAM  ( Certification) Federal Institute for Materials Research and Testing (Bundesanstalt fur Materialforshung und prufung  = Acronym BAM in German)  

6210-vp =?????  part of BAM certification ??

http://www.lexingtoncontainercompany.com/Nato-Jerry-Cans.html

They have yellow green red blue and black

Those are some nice cans

I just received a four-pack from Atlantic British with the same UN code on the handle.  The only difference is the logo on the side which is a V with a flame above it.  



 

Wow, I just worked my way through this 30 page posting.  What a wealth of knowledge.  I was getting ready to take the plunge and order a 4-pack from AB.  However, I came across this and was wondering if this would be a viable option for long term storage. They lay flat an 2 would give me 28 gal for my truck vs 6 Jerry cans.

Here is the link.

http://www.flo-n-go.com/products/product_duramax/

No link

Added link thanks.  I hate when that happens.

Get the jerry cans

You will thank me later

14 gallons is 91 pounds of gas.  Most wemon and kids cannot lift that out of a vehicle

The hand pump is a failure point and I think you have to keep squeezing it to pump fuel.  If it pumps a cup per squeze that is 16 squezes per gallon or 128 squeezes to fill an 8 gallon Corolla.  I'm gonna cry if I count how many squeezes to fill a 40 gallon Suburban.

Thanks PA22-400 for the advice, I made the order for 4 cans from Atlantic British.  Now to get a couple super siphon.  

Not nearly robust enough, and you'll likely find they leak fuel -nicely!  

I have done the Google +arfcom searches, and a lot of back and fourth is what I got.