How Much Gas Do I Have Left?

OK, so you're off out in the woods, away from cars and roads and all. Sure would be nice to have a second cup of coffee on a cold morning and heck how about heating up some water so you can wash your face -- but can you spare the extra stove gas? Dang it, those cute little backpacking canisters are sealed. Aw, heck, better skip it just to be safe. Too bad too, since you'll probably come back with gas left over, and that second cup of joe sure would have been good.

Ever been there? Well, in my latest article on Seattle Backpackers Magazine, there's a simple and hopefully practical way to estimate how much gas is in that little sealed canister: How Much Gas Do I Have Left?

Feedback appreciated as always.

HJ

Neat, never thought about doing that!

Very good - thanks for posting

A reader on SBPM suggested that it would work even better if one turned the canister upside down so that there's no air pocket underneath. I haven't tried it, but it makes sense.

HJ

If you do that right before using, would water in valve cause any problems?

It might, although you could probably blow it out by mouth.

A better solution might be to only buy canisters that have good tight fighting lids, like Snow Peak brand. Keep the lid in place when you put the canister upside down in the water.

HJ

Jim,

Being an engineer, I do it with numbers! I weigh each canister (although they are pretty close). When in the field I float the canister in a measuring cup, 8 oz to the cup (or for those who like metric - 1 cc = 1 gm). Then I know how much fuel I have left.

Being me, I also write the new canister weight and purchase date on the bottom and carry the Sharpie with me and make a mark for every liter of water I boil or the simmer time if it is at less than full throttle. Since I have an idea of the usage, I have a good idea of the remaining stock.

Respectfully,

Jerry

Immediately after you turn your stove off, there will be some condensation on the outside of the canister matching the level of the liquid in the canister. You do have to look right away, but you can mentally track your levels all along, or mark them.

Hi, Jerry, so how does this work? For every additional cc you can add to the measuring cup, you figure you've burned one g of fuel? Is that the idea?

I write the date and weight on the canister after each trip. This gives me a pretty good idea of how much gas I use on trips.

HJ

That's always been one of the nice things about liquid fuel stoves. You know exactly how much fuel you have left.

I've got a couple of Pocket Rocket canister stoves, and their simplicity and light weight is nice for a day hike or whatever. However, anything more than that and I'm taking my XGK.

Aye. It is nice to pop off the lid and give 'er the old eyeball.

Still, the float method comes pretty close, and, God willing, you planned for enough gas + a margin of error prior to your trip anyway.

There are absolutely advantages to white gasoline though:
1. Inexpensive. A canister of gas costs generally around $5.00 for 100g. The equivalent amount of white gasoline? Around $0.30.
2. Environmental. There is no canister to dispose of with white gasoline; one simply refills. And yes you can recycle a gas canister, but the canister must still be transported, melted, re-formed, and re-filled, all of which have their environmental costs.
3. Cold weather. White gasoline will burn well in as low a temperature as any stove can operate.
4. Survival. Pop open that white gas bottle, pour a little on a rain soaked pile of wood, and presto! you've got fire.
5. The semi-imponderable. You get to use really cool old stoves like a Svea 123 if you use white gasoline.

HJ

The way it's going it won't be for long, Coleman fuel has already gone to $20 per gallon, used to be $8-ish a couple years ago.

Bulk naphtha is cheaper from what I hear but most people don't have a source for it (and I've looked).

Coleman fuel is still $8.88 at the Walmart near me. My quote of about $0.30 for the amount of white gasoline equivalent to a 110g gas canister is based on that $8.88/gallon price.

At sporting goods stores, it's more like $11.00/gallon, which is still far cheaper than the cheapest canister gas.

Supposedly, in some parts of the country (Amish country so I'm told) true white gasoline is still available. I remember buying true white gasoline with my dad in rural California in the late 60's/early 70's. By "true" white gasoline I mean gasoline without the additives in Coleman fuel or the additives in automotive or aviation gasoline. I haven't see true white gasoline anywhere in years and years.

Even if it goes to $20.00/gallon, count yourself lucky. Overseas in Europe and Australia, they pay more per liter than we do per gallon. And even at $20/gallon, Coleman fuel would still be vastly cheaper than canister gas. At $20/gallon, the equivalent of a 110g gas canister would cost about $0.75 instead of today's $0.30, and who know how much canister gas will cost by then?

The other big advantage to liquid fueled stoves (not so much white gasoline but "multi-fuel" stoves) is in international travel. Who knows what kind of gas canister you may find in out of the way places? There are still a lot of parts of the world where the old piercable canisters (i.e. canisters that you puncture and cannot remove the stove once punctured) are all that you can find. Elsewhere, only non-threaded Camping Gaz type canisters can be found. Still elsewhere, no canisters of any kind can be had whatsoever. But various types of gasoline and kerosene will be available wherever there is anything even vaguely resembling civilization. If you get a really rugged stove like the XGK, you can burn everything from 2 stroke motorcycle fuel to av gas to jet fuel to nasty farm diesel.

HJ

Paint stores carry naptha, at least in the states. I know I've seen 5-gallon pails of it at Sherman Williams (apparently they also sell it in other container sizes). No idea what they cost though.


You might have to ask for it though. They likely don't keep it on the shelves to deter people from buying it for use in the production of the drug DMT.

Even in the US, canisters can be hard to find. If I had only one stove, it would run on liquids. But the convenience and relatively light weight of canisters stoves have made them part of my kit for years.

For ultimate lightweight and versatility, there is the good old wood fueled cooking fire, as long as the weather cooperates (neither too wet or too dry...)

Nor too windy!

HJ

Jim, I envy you with your cheap coleman fuel price, I think that's cheaper than what I pay for kerosene!

Careful using gasoline in stove though, if it has ethanol in it that stuff eats plastic like no tomorrow, almost killed my Brunton vapor with it.

Naptha is Very High-Octane,very similar to Acetone,of which is Readily explosive.Leave a capful out for a 1/2 hr,& You will notice that it has evaporated!I would NOT recommend using this in any form for a stove or fire situation,Mothballs are made from this, to get an idea of what you would be cooking food with or boiling water for drinking,If you did manage to Not blow-up!

Naptha is actually one of the low-octane components of gasoline. That's why you generally don't want to use naphtha/lighter fluid/coleman stove fuel (which are all naptha based) in your vehicle, as it will lower the octane and potentially cause detonation. IIRC, fuel for camp stoves is around 50 RON (the octane scale), whereas gasoline for automobiles is typical in the 80's+.

With that said, there are other differences between the products, that can effect interchangeability. I'm not a chemist, so I can't tell you which are safe to use. The question that I answered was simply, where would one find a source of naphtha?

IIRC, Blast works as a chemist in the petro-chemical industry. He would probably be able to confirm whether or not one could safely use painter's naphtha in a liquid fuel camp stove.

Jim,

I float the canister in a large measuring cup and use the amount of water displaced (final volume - initial volume) to determine the weight. That tells me (from the intial weight on the bottom of the canister) how much I have used. If you do not have a measuring cup that large you can use your technique, put the canister in a pot, fill with a measured amount of water to the top, subtract that from the capacity of the pot & have your weight. Another way would be to put the canister in the pot and fill it with water, take the canister out then measure the amount of water required to fill the pot again. There are, I'm sure, other methods of using displacement to weigh anything that floats, just remember that the weight of water displaced is equal to the weight of the object.

If you carry a graduated cylinder, it will be much more precise.

Respectfully,

Jerry

Kerosene is generally more expensive here in urban Los Angeles than Coleman fuel. In a rural area, I suspect the reverse to be true. Alcohol for a stove is also more expensive than Coleman fuel here.

I don't normally use automotive gasoline in any of my stoves, although I might in an emergency. Good point about ethanol though. The seals and such in a stove could definitely be eaten alive by the gasoline-ethanol combo commonly sold here in the US. Coleman fuel, in the amounts I burn it, is very affordable. Yes, it's at least double the price of automotive gasoline per gallon, but one gallon of Coleman fuel will generally last me a year. I'm not going to go risking a $75 to $150 stove to try to save less than $9/annum.

HJ

Paul,

I haven't used Naptha myself, but in the UK, people I have talked to commonly use "panel wipe" (naptha) as a stove fuel. It's reputed to have a little less power than Coleman fuel but is supposed to work well.

I've also talked to people who have used "environmental" gasoline (gasoline without anti-knock additives). The brand name I've heard is Aspen 4T. I'm not aware of Aspen being available in the US. Supposedly "environmental" works even better than panel wipe. "Environmental" gasoline is targeted toward being used in things like lawnmowers and such.

From Optimusstoves.com:


HJ

Ah, I get it. Nice. With your technique, you can make much better estimate of how much fuel you have left.

When you get home, do you weigh the canister again? Are your water based estimates pretty close to your scale-based weights? I imagine they'd be pretty close.

The one advantage of my technique is that you can get a rough estimate at a glance, much like the fuel gauge on a car, without having to do any calculations, but your technique is quite a bit more precise.

HJ

Sounds like I need to move to where you live.

Methanol runs about $12/gallon, coleman fuel $19/gallon, kerosene $14. I wonder if it's because I live in an urban area, they figure they can charge whatever they want and the clueless/choiceless urbanites will pay for it.

Yipes! Are those US or Imperial gallons? If those are US gallons, you're paying at least twice as much as I do for Coleman fuel.

Shoot, about an hour away from you, there's a Walmart Super Center in Plattsburgh, NY. You ought to call them and see what they sell Coleman fuel for. Then all you need is an excuse to head south to make the drive worthwhile.

HJ

Those prices are about the going rate here also. In a few weeks though, stores start putting kerosene and Coleman fuel on sale to get rid of summer stock and usually there is substantial price drop, especially for the Coleman fuel.

I'll have to keep an eye out, but I don't ever recall seeing them on sale.



Those are US gallons, heh, maybe I'll have to stop by plattsburgh someday, though I don't know what the customs guys will say when I head back with trunk full of liquid fuel lol.

Just don't stick a lot of wiring and timers back there too.

Of course if you had a bunch of camping gear in your trunk and that nice shiny can of brand new Coleman fuel just happened to have been decanted into old beat up fuel bottles stored next to your battered, well-used camp stove, why no one would be the wiser, now would they?

HJ

Thanks for the brilliant tip about floating canisters to gauge the amount of gas left with precision. So far, I've only done the hand shaking test (subjectively judging the weight of a partly filled canister versus a full one, and getting a feel of how much liquid gas there is sloshing around in there). Looking forward to trying out your method.

I have the same objections to gas canisters as I have to primary batteries: They seem to be either full (in which case I am reluctant to break the seal and use them), or almost all empty (leaving me in the dark/cold after 5 minutes or so).

If I carry a full canister I can resort to only carry one. If I insist on using up my half-filled canister I have to bring two, because I can't really trust the half empty to work. As a result, there is a collection of half-filled canisters in my shed...

This is a common problem (half filled canisters laying about).

Several uses for half filled canisters:
1. Take 'em day hiking where you don't need a full canister and make tea or soup for lunch.
2. Use 'em with a micro lantern. Lanterns typically burn gas at a much lower rate than a stove, so that half full canister may last a good long time.
3. Take 'em car camping where weight isn't so critical. You can throw a hole bunch of half full canisters into your kitchen duffel (or box or whatever) and burn 'em until all used up.
4. Invest in a refiller (at your own risk, not a standard or approved practice) so you can top off your canisters.

HJ