View Full Version : Guesstimating fuel-remaining...
I'd be interested in knowing tricks & techniques used to gauge fuel-remaining in canister stoves and JetBoils. For many years, I avoided these stoves for serious backpacking... partly because of the uncertainty involved. (At least with a Whisperlite, you can open the fuel bottle and look inside.)
Anyway, I've always found it a bit challenging to know how long a canister will last, or how much fuel is left. So, erring on the side of caution, I'm sure I've abandoned several canisters along the way that were nowhere near empty. Hard to tell from weight (at least with the "small" canisters) because the canister out-weighs the fuel.
I would think there would be a market for a small, cheap (and of course, weightless) gadget that could make this measurement, with reasonable precision.
Just shake the can every time just before you hook it up. You'll learn..
Panzer
Just shake the can every time just before you hook it up. You'll learn..
Panzer
I do that, of course. My hearing isn't all that great. A few ml. of propane doesn't make much sound. I've never actually exhausted a canister. I just ditch it and get a new one before that happens. Seems a bit wasteful, but I don't want to go without hot meals (or tea) for any length of time.
take-a-knee
06-05-2008, 20:42
Weigh it before and after.
Weigh it before and after.
That doesn't help on the trail. You can try to "train" yourself to guess the weight, but it's still just a very imperfect guess.
Odd Thomas
06-05-2008, 20:51
I would think there would be a market for a small, cheap (and of course, weightless) gadget that could make this measurement, with reasonable precision.
Are these for the same cannisters?
http://www.basegear.com/gasgauge.html
saimyoji
06-05-2008, 20:51
There have been one or two (at least) threads on this before, but I couldn't be bothered to find them.
http://www.modernoutpost.com/gear/details/br_gas_gauge.php
Are these for the same cannisters?
http://www.basegear.com/gasgauge.html
Any reports on how well they work? Any field reports? Buehler?
Odd Thomas
06-05-2008, 21:03
Any reports on how well they work? Any field reports? Buehler?
Looked all around and none of the review sites have any reviews yet, but for $5 you can't go too wrong, and virtually weightless.
Looked all around and none of the review sites have any reviews yet, but for $5 you can't go too wrong, and virtually weightless.
The weightless part, for sure...
ShakeyLeggs
06-05-2008, 21:10
When I used canister stoves I always carried a spare. That way I really didn't have to worry about running out. But then again that was back when I usually did weekend to week length trips, I now use alcohol. All I have to do is unscrew the cap and see how much is left in the bottle. YMMV
Appalachian Tater
06-05-2008, 21:46
Isn't there some trick about floating them in water?
Odd Thomas
06-05-2008, 21:53
Isn't there some trick about floating them in water?
If she floats, she's a witch!
I do that, of course. My hearing isn't all that great. A few ml. of propane doesn't make much sound...
When I shake them I don't actually listen, I "feel" how much is left.
Also, when you are getting low, you can carry small spear and then use the big one until it is completely gone shaking it each time you use it so you learn.
The small spear does not have to be full either.
Panzer
A small spear??
What is stabbing it going to do for you???:-?
A small spear??
What is stabbing it going to do for you???:-?
maybe panzer means "spare"? :-?
maybe panzer means "spare"? :-?
I know, but it was too funny to not comment on it…
take-a-knee
06-06-2008, 00:00
That doesn't help on the trail. You can try to "train" yourself to guess the weight, but it's still just a very imperfect guess.
If you weigh a full canister, use it on a trip and cook your typical meals with it, then weigh it when you return, you'll know your usage per day after you weigh an empty cannister and subtract that from what is left. Calculating what is left in any cannister, and how many days use you can get from it should be easy at that point.
Back to the original post in this thread, I have also stayed away from canister stoves for the same reason. At best it’s difficult to know exactly what is in one and almost always too involved (weighting them , making a guess of how much fuel you will use for a varying dinner menu) then it’s worth. Weighting them when full and then again when empty doesn’t really tell you much other then what the fuel weights. Not how much fuel you use for any given meal. Throw in variables of temperature (air temp and starting temp of your water or food) wind and your precision measurements (that are impossible to do on the trail) are next to useless.
This is why most just pack another canister and have lots of canisters at home that are somewhat empty. I do this with propane canisters when I car camp. But at least I’m not carrying them on my back. And I have an adaptor for refilling them, so it’s a little better then it is with butane.
I still like my Svea, I can look into the tank to see what’s left in it. And in 30+ years it has never once let me down.
fiddlehead
06-06-2008, 00:08
So many people making life so complicated on the trail.
Just shake it and learn what an empty one feels like. It doesn't take long to figure out what one day or two days left means by the shake.
It's easy to conserve as you get low: use a lid (tight fitting is best), put your food in before you start to heat and stop cooking once it boils and then let it sit for 10 minutes. OR, build a small fire and cook some of your meals on it when you are getting low and the weather is nice.
If you weigh a full canister, use it on a trip and cook your typical meals with it, then weigh it when you return, you'll know your usage per day after you weigh an empty cannister and subtract that from what is left. Calculating what is left in any cannister, and how many days use you can get from it should be easy at that point.
I did all that, with a vengeance. Boiled many cups of water and measured canister weight before and after. Long term, I figured about 0.1 oz for each cup of water boiled (which means about 40 cups boiled per small canister.)
My point is this... you start with either 4 or 8 oz of fuel, with the canister itself adding somewhere between 3 and 5 oz. I know to swish and heft the canister, and I can certainly tell that it's getting near empty. But I've never dared to take one all the way to zero, at least not on the trail. It turns out that the canisters lasted longer on the trail than I'd expected. But I still ended up leaving them behind, knowing that they're not completely empty... and wondering just how much fuel I'd left behind...
fiddlehead
06-06-2008, 03:50
So, burn one till it Does run out!
I don't understand the confusion?
Hey, it's no big deal, folks. No need to get excited. I'm just a bit curious about how much fuel I'm wasting... a half-ounce here, a half-ounce there. Being a bit of a gram weenie, I can't see carrying a spare canister, so yeah, that's my choice. Plus I have a few of these things at home in various half-empty states. I guess I can use them for weekend hikes and such.
take-a-knee
06-06-2008, 14:14
Hey, it's no big deal, folks. No need to get excited. I'm just a bit curious about how much fuel I'm wasting... a half-ounce here, a half-ounce there. Being a bit of a gram weenie, I can't see carrying a spare canister, so yeah, that's my choice. Plus I have a few of these things at home in various half-empty states. I guess I can use them for weekend hikes and such.
That was my whole point about weighing the thing full and empty. You'll have several partial containers that can be used for overnighters. When they are completely empty you can jab a screwdriver into them and recycle them.
gearfreak
06-06-2008, 14:37
Here's my reply (http://www.whiteblaze.net/forum/showpost.php?p=616634&postcount=28) to a similiar question asked awhile back. It seemed to get a positive response. Hope it helps. :cool:
Pedaling Fool
06-06-2008, 15:12
Here's my reply (http://www.whiteblaze.net/forum/showpost.php?p=616634&postcount=28) to a similiar question asked awhile back. It seemed to get a positive response. Hope it helps. :cool:
That's interesting, but I get much more out of a 4oz canister with my Jetboil, so I guess it depends on stove type, barring all other factors. With a 4oz canister I use about 25 minutes per day and get at least one week use, sometimes more. That's 7 x 25 = 175 minutes. I haven't used an 8 oz container for a while, so I will not guess how long it will last, but seems like it should be about two weeks.
Note: I don't, usually, boil water, because there is just no need too. I use my Jetboil for it's outstanding simmering capability - cook 20-30 minute rice for dinners.
gearfreak
06-06-2008, 16:00
That's interesting, but I get much more out of a 4oz canister with my Jetboil, so I guess it depends on stove type, barring all other factors. With a 4oz canister I use about 25 minutes per day and get at least one week use, sometimes more. That's 7 x 25 = 175 minutes. I haven't used an 8 oz container for a while, so I will not guess how long it will last, but seems like it should be about two weeks.
Note: I don't, usually, boil water, because there is just no need too. I use my Jetboil for it's outstanding simmering capability - cook 20-30 minute rice for dinners.
That's outstanding fuel efficiency. Jetboil's website states that the PCS can boil 1/2L in two minutes and the 100g canister will boil about 12L. I figure that's approximately 48 minutes of burn time per 4oz canister by their measures. You're doing something right! :cool:
Pedaling Fool
06-06-2008, 16:13
That's outstanding fuel efficiency. Jetboil's website states that the PCS can boil 1/2L in two minutes and the 100g canister will boil about 12L. I figure that's approximately 48 minutes of burn time per 4oz canister by their measures. You're doing something right! :cool:
To do that you got to open up the fuel valve. I never "open up" the valve, when I simmer I got the valve open just enough to keep a flame. Jetboil should advertise more on the stove's great simmering capability and not so much on the boiling time.
P.S. I've met numeous hikers that can make a 4oz canister with a Jetboil (does not need to be Jetboil fuel canister) last a month or longer. This is cooking one meal a day that requires no simmering, i.e. ramen noodles....