How Much Gas Do I Have Left?

7:10 p.m. on July 15, 2011 (EDT)
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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, here'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?

HJ

8:39 p.m. on July 15, 2011 (EDT)
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Jim I keep getting hit with a 404 code(page not found.)

8:58 p.m. on July 15, 2011 (EDT)
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Rick,

It sees to be working for me.  Give it another shot.

HJ

9:09 p.m. on July 15, 2011 (EDT)
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Cool, I am gonna check this out. Maybe it was something on my end. I got that code 3x before I messaged you.

9:13 p.m. on July 15, 2011 (EDT)
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HJ,

I gotta say that is actually a pretty good way to monitor your fuel levels. Thanks alot for throwing this out there, I am about to finish a can of iso now and I have newbies in the man cave. This is a great help. Simple too. Thanks again. -Rick

10:34 p.m. on July 15, 2011 (EDT)
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Hi, Rick,

Yeah, it's been helpful for me on occasion, like when I'm trying to avoid bringing a second canister and want to make sure not to run out of gas.

It works even better if you float the canister upside down.  Looks funny, but then you've got no air pocket.

HJ

10:34 p.m. on July 15, 2011 (EDT)
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Thanks, Jim.

                                             ~r2~

11:17 a.m. on July 16, 2011 (EDT)
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Interesting, thanks for sharing this. I wonder how someone figured that out to test the level of the gas inside?

I find too that if you warm the canister before using it by cupping both hands around it, it will work better. Especially in colder weather. And then wrap a Tshirt or put a sock over the canister to hold the warmth in while cooking.

And to save fuel:

Heat the meal to boiling, turn off the stove and let sit for a few minutes.

When I cook pasta, I bring the water to a boil, add the pasta, bring back to a boil, turn off the stove, set my cook pot on a spare tshirt and wrap it around to insulate the pot, let it sit insulated for 10 minutes, add the other ingredients and stir, then let sit anout 5-10 minutes and eat.

This method saves fuel, boiling water loses only about 10 degree's every 10 minutes in a insulated pot.

You can also pre-soak pasta in cold water for about 30-60 minutes and it will still absorb the water then just bring it to a simmer. Time amount differs with elevation/air temp conditions.

You can also precook pasta at home before a trip, then dehydrate it. Then when you want to eat it bring the water and it to a simmer and its ready to eat.

Instant rice can also be made in the same manner. Precook it, then dry it and when you want it in a meal, just bring to a simmer or add to something else.

I tested idea's like these at home or on slow days at restuarants I have worked in. Most of the ways I cook in the field were pretested over 30 years ago.

7:58 p.m. on July 16, 2011 (EDT)
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GaryPalmer said:

 Interesting, thanks for sharing this. I wonder how someone figured that out to test the level of the gas inside?

 Gary:

Not sure how it occurred to me.  I guess I just knew you could displace a certain amount of water with a certain amount of weight and that canisters are filled by weight.  Hope it's useful for you.

Thanks also for the fuel savings tips.

HJ

1:47 p.m. on July 18, 2011 (EDT)
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Very nice tip. Thanks.

12:27 p.m. on July 20, 2011 (EDT)
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I'm using that trick.

Wife says I'll never run out.

1:01 p.m. on July 20, 2011 (EDT)
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Awesome idea

10:55 p.m. on July 20, 2011 (EDT)
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I have been using this technique since canister stoves first came out in the sixties.  One thing I would suggest is inverting the canister, immersing it bottom side up.  The concave base will entrap air, if placed in the water right side up, but the amount entrapped can vary, and will throw off the accuracy of this method.

A friend borrowed a trick from his son's chemistry set, and paints a strip of temperature sensitive compounds on the side of his canisters.  Once in use, the temperature difference between the gas and liquid contents can be seen, and used to indicate remaining fluid volume.  It appears to work just as well as Jim's idea, but my friend does only warm weather camping.  Another approach may be adapting those liquid crystal fuel level indicators sold by BBQ grill stores intended for use on LPG tanks.  Both of these solutions probably don’t work when ambient temps are at or below the dew point of butane, as no thermal difference would exist between gas and liquid. 

Ed

12:11 p.m. on July 21, 2011 (EDT)
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Brunton does this on theirs Ed

1:16 p.m. on July 21, 2011 (EDT)
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Does anyone have actual experience with using the Brunton "fuel gauge?"  I'm wondering how well they work and how practical they are.

HJ

1:43 p.m. on July 21, 2011 (EDT)
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KISS is an amazing acronym

4:20 p.m. on August 1, 2011 (EDT)
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Tried it last night.  Great idea HJ. 

6:36 p.m. on August 1, 2011 (EDT)
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Thanks.  There are times when despite your best planning it's good to be able to figure out how much fuel you have left on the fly -- like when the guy in the next campsite lays three fresh trout on you that he just can't eat.  Do you have enough fuel or don't you?

HJ

1:43 p.m. on August 27, 2011 (EDT)
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Manufacturers could make this process much easier if they just put the float marks of the side on the canister for us at the factory. A few calculations and add a few bold lines on the painted label during production is all it would take.

For those not afraid of using a calculator you can estimate the empty mark. Float the tank to find the full mark. Next, measure the inner diameter of the fuel tank. My 100gm tanks measure about 8.5cm and 227gm around 10.5 cm.

I know all the "Parrot Heads" out their are screaming at the top of their lungs the lyrics "Math $#@%$" but please just hear me out.

If you are math-phobic, just jump to the last lines now.

1 cubic centimeter(cc) of water displacement weighs 1 gm and equals the buoyancy force of the displaced fuel.


     V = r^2h where the displaced volume equals the fuels total weight

If 100 gram cylinder = 8.5cm dia = 4.25 radius

     100gm = 3.1415 * 18.06 * H
     H = 100gm /(56.74)
     H = 1.76 cm full-to-empty

If 227 gm cylinder = 10.5cm dia = 5.25 radius

     227gm = 3.1415 * 27.56 * H
     H = 227gm / (86.588)
     H = 2.62 cm full-to-empty

These heights for the cylinder should reflect the change in float level full-to-empty for a canister tank.

Now that the math is done go back to the first mark(full) that you put on your tank while at the kitchen sink and measure down and mark the empty point.

Sure would be easier for some egghead at the factory did this for us now wouldn't it?? Till then maybe this will help.

AR

2:44 p.m. on August 27, 2011 (EDT)
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Some other methods are you just pick up said canister in question and slosh it. It seems quite easy to tell how much is in it by feeling the canister. I do the same thing with my larger lpg tanks for the grill, can easily tell if it is full, half, 1/4 etc

You can also get a rough idea by calculating the run time used (even easier if you have a watch, phone etc with a stopwatch), and at the end of the trip write it on the side of the canister so you know you have roughly x amount of time left.

2:39 p.m. on August 31, 2011 (EDT)
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anlrolfe said:

Manufacturers could make this process much easier if they just put the float marks of the side on the canister for us at the factory. A few calculations and add a few bold lines on the painted label during production is all it would take.

For those not afraid of using a calculator you can estimate the empty mark. Float the tank to find the full mark. Next, measure the inner diameter of the fuel tank. My 100gm tanks measure about 8.5cm and 227gm around 10.5 cm.

I know all the "Parrot Heads" out their are screaming at the top of their lungs the lyrics "Math $#@%$" but please just hear me out.

If you are math-phobic, just jump to the last lines now.

1 cubic centimeter(cc) of water displacement weighs 1 gm and equals the buoyancy force of the displaced fuel.


     V = r^2h where the displaced volume equals the fuels total weight

If 100 gram cylinder = 8.5cm dia = 4.25 radius

     100gm = 3.1415 * 18.06 * H
     H = 100gm /(56.74)
     H = 1.76 cm full-to-empty

If 227 gm cylinder = 10.5cm dia = 5.25 radius

     227gm = 3.1415 * 27.56 * H
     H = 227gm / (86.588)
     H = 2.62 cm full-to-empty

These heights for the cylinder should reflect the change in float level full-to-empty for a canister tank.

Now that the math is done go back to the first mark(full) that you put on your tank while at the kitchen sink and measure down and mark the empty point.

Sure would be easier for some egghead at the factory did this for us now wouldn't it?? Till then maybe this will help.

AR

 

A very interesting method.  Math isn't my strongest suit, but it sounds like it should work.  I agree though that if the manufacturers just put water lines (one for full and one for empty) that would be the best situation.

HJ

2:44 p.m. on August 31, 2011 (EDT)
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TheRambler said:

Some other methods are you just pick up said canister in question and slosh it. It seems quite easy to tell how much is in it by feeling the canister. I do the same thing with my larger lpg tanks for the grill, can easily tell if it is full, half, 1/4 etc

You can also get a rough idea by calculating the run time used (even easier if you have a watch, phone etc with a stopwatch), and at the end of the trip write it on the side of the canister so you know you have roughly x amount of time left.

 

I think the "shake test" has some value although I generally like having something that gives me a bit better idea of how much fuel I've got left, particularly toward the end of a multi-day trip.

The run time method doesn't seem like it would be very helpful to me.  Just knowing how long you've run the stove isn't enough unless you know how high you've been running the stove.  To me it's too hard to tell exactly how high that flame is by eye -- unless you always run your stove on maximum setting.   If you're always running your stove on maximum, you're wasting a lot of fuel.  It's much more efficient in terms of amount of fuel burned to boil a given amount of water if you use a low to medium flame.

HJ

6:28 p.m. on September 1, 2011 (EDT)
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Got a reply from Cascade designs concerning fuel marks and my formal design proposal:

AR,

Thank you for submitting to Cascade Designs your idea for including fuel indicator marks on MSR(R) canisters. Currently, Cascade Designs and MSR engineers are already in the development process for introducing a similar concept to the market. This idea has been independently pursued within our own labs for some time, however we would still like to thank you for your interest in Cascade Designs and MSR products.

Kind Regards,

(C) 2011 Cascade Designs, Inc.

anyone want to guess what this smells like??

AR

8:08 p.m. on September 1, 2011 (EDT)
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anlrolfe said:

Got a reply from Cascade designs concerning fuel marks and my formal design proposal:

AR,

Thank you for submitting to Cascade Designs your idea for including fuel indicator marks on MSR(R) canisters. Currently, Cascade Designs and MSR engineers are already in the development process for introducing a similar concept to the market. This idea has been independently pursued within our own labs for some time, however we would still like to thank you for your interest in Cascade Designs and MSR products.

Kind Regards,

(C) 2011 Cascade Designs, Inc.

anyone want to guess what this smells like??

AR

 

Perhaps --  but if enough people ask about something like this, MSR will eventually respond.  Thanks for doing your part.

HJ

10:13 p.m. on September 15, 2011 (EDT)
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Been doing this for several years. But ya gotta be sure there is no air trapped under the concave canister bottom when immersing it if you want accurate measurements.

10:16 p.m. on September 15, 2011 (EDT)
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Never mind. This technique was already mentioned in another reply above.

9:16 p.m. on September 23, 2011 (EDT)
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I've been following this thread out of interest, as I've contemplated a canister stove.  But this thread just bolsters my opinion that I'm glad I've stuck with liquid fuel stoves.  When I need to check the remaining fuel, I just un-screw the bottle cap and look inside!  :).

3:49 p.m. on September 27, 2011 (EDT)
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That is one of the advantages of a liquid fueled stove.  Also liquid fuel, well, white gasoline at least, is extremely cheap.  A 110g canister of gas costs about $5.00.  The same amount of white gasoline costs about $0.30.  White gasoline also makes an excellent fire starter.

There's no "dead" canisters to pack out with liquid fuel; the liquid fuel bottles are fully reusable (I have several bottles dating back to the early 60's).

Liquid fuel stoves scoff at cold weather.

Of course, you do have to learn how to prime, and there's always some set up (pump and prime).  Priming is less of a big deal if one uses alcohol.  The other drawback to liquid fueled stoves is (generally) lack of precise flame control although a number of higher end stoves have a valve-at-the-burner that allows for really good flame control.

HJ

8:59 a.m. on September 28, 2011 (EDT)
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A wise man once said,

Priming builds character

For those who argue weight, I'll counter with reliability. I purchased my 1st canister stove as a matter of curiosity. I then had to get a pot set to accompany it. After a few uses the inevitable happened, my estimate of fuel came up short and the day hike that I was on ended up barely lukewarm. Not a proper way to make anything to warm the bones. For all the convenience of instant on, I was inconvenienced with a nearly cold meal and nothing warm to drink.

If I was to combine the canister stove, canister and solo cook set on the scale I would suspect that it would be very close in weight to my trusty SVEA 123.

As hikin jim mentioned :

There's no "dead" canisters to pack out with liquid fuel; the liquid fuel bottles are fully reusable (I have several bottles dating back to the early 60's).

Does that mean that a liquid fueled system can be seen as being more sustainable because you reuse instead of recycle? Some multifuel stoves can burn biodiesel from what I have read

So, in closing, should you shake it, weight it or just open the cap and look inside. I can do the latter w/ my friend the SVEA 123

AR

3:39 p.m. on September 28, 2011 (EDT)
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anlrolfe said:

A wise man once said,

Priming builds character

lol. My, what a wise saying. ;)

 

For those who argue weight, I'll counter with reliability. I purchased my 1st canister stove as a matter of curiosity. I then had to get a pot set to accompany it. After a few uses the inevitable happened, my estimate of fuel came up short and the day hike that I was on ended up barely lukewarm. Not a proper way to make anything to warm the bones. For all the convenience of instant on, I was inconvenienced with a nearly cold meal and nothing warm to drink.

Yeah, the whole fuel thing with canisters can be a pain. Most folks just make sure to start all their overnight trips with a full canister. I myself bought a refiller on eBay. I top off my canisters before I head out.

If you're going out on a trip with a less than full canister, weighing is the most accurate way to tell how much fuel is left, but you still need to know about how much fuel you will need. 30g/day in fair weather for a two person team is a pretty standard number. 20g/day for a soloist might therefore follow. You'll probably need to double that number if you're melting snow.

 

As hikin jim mentioned :

There's no "dead" canisters to pack out with liquid fuel; the liquid fuel bottles are fully reusable (I have several bottles dating back to the early 60's).

Does that mean that a liquid fueled system can be seen as being more sustainable because you reuse instead of recycle?

Yes. Liquid fuel is absolutely more sustainable/lower impact. Even if you recycle the gas canisters, they still have to be transported, disassembled/melted down, and re-formed, all of which require energy and have associated environmental impacts. I'm still using fuel bottles that were my dad's or my uncle's that have been in the family since the early 60's. Definitely a lower impact.

The most sustainable of all would be "green" alcohol used as a stove fuel.

 

Some multifuel stoves can burn biodiesel from what I have read

That would be a step in the "green" direction. Unfortunately, most stoves that I'm aware of don't burn well on biodiesel. I wish I could recommend a stove for such a fuel, but I don't know of one that works well.

 

So, in closing, should you shake it, weight it or just open the cap and look inside. I can do the latter w/ my friend the SVEA 123

There's something to be said for the simplicity of just opening the cap and looking inside as a fuel check. I won't argue against such simplicity, but the "float the canister" method does work pretty well in the field if one has gone ahead and decided that canister gas is the way to go.

 

HJ

5:11 p.m. on October 4, 2011 (EDT)
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hikin jim said;

Yeah, the whole fuel thing with canisters can be a pain. Most folks just make sure to start all their overnight trips with a full canister. I myself bought a refiller on eBay. I top off my canisters before I head out.

Jim, what do you look for to get a good refueling adapter for the gas canisters, and how do you go about refilling?  That sure would make a week end hike far simpler.

5:45 p.m. on October 6, 2011 (EDT)
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Guyz,

I bought the one shown from world_wide_2009 on eBay.  I think it was $43, which isn't cheap, but then again the 113g canisters are typically $5 each and the 227g canisters are $6.  I refill using 100% butane canisters I get at the dollar store (for $1).  It doesn't take all that long before the refiller pays for itself, and I can custom fill.  If I go on a trip where I calculate I need 150g of gas, I bring 150g of gas not a full 227g.

I can also top off half full canisters so that they're useful again.


P1020212.jpg
Gas canister refiller from eBay


P1020211.jpg
Dollar store gas canister.  $1.00 for 227g of butane.


P1020213.jpg
This end attaches to the backpacking canister


P1020214.jpg
This end attaches to the dollar store canister


P1020219.jpg

They connect up like so.

You then open the valve and let gravity do the work.  I usually leave them overnight.

HJ

6:25 a.m. on October 7, 2011 (EDT)
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Jim ~~

Is there an overflow-prevent feature with this device?

~ r2 ~

1:40 p.m. on October 7, 2011 (EDT)
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hikin jim said;

 I refill using 100% butane canisters I get at the dollar store (for $1).  

I take it you just do this for warm weather refills?  Do you just buy the new iso pro canisters for cold temps or do you have another source when you need to refill during winter?

1:31 p.m. on October 10, 2011 (EDT)
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Robert:

No, there's no overflow preventer with this.  However, butane has fairly low vapor pressure and is relatively safe.  You know those cheapie little plastic lighters that everyone carries?  That's liquid butane in there.  If the cheap little plastic body can  handle the pressure, how much more so a steel canister that was designed for propane and isobutane, both of which have higher vapor pressure than butane, especially propane.

What I do is weigh the canister.  By monitoring the weight of the canister, I can usually fill within a few grams of the stated weight.  As a practical matter, I don't seem to have much in the way of trouble with over-filling.

HJ

1:40 p.m. on October 10, 2011 (EDT)
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Guyz:

Yes, good observation.  100% regular butane is a poor fuel if the fuel temperature falls below about 40F/5C.  But for fair weather use, it's great,  and it is a cheap source of fuel.  I do the majority of my backpacking from late spring to early fall, so butane actually works well for me. 

I'm not aware of a cheap source of isobutane or I'd use it for refilling.  There are plenty of cheap sources of propane, but you DO NOT want to refill a backpacking canister with 100% propane.  Propane has very high vapor pressure and will not be safe in a standard backpacking canister.  For 100% propane, you need a heavy steel canister like the green Coleman brand propane canisters.

For colder weather, I use store bought backpacking canisters, and I pick a brand that is propane-isobutane (no regular butane) ~OR~ I'll just switch over to liquid fuel which is pretty much the cheapest backpacking fuel out there. 

HJ

9:09 a.m. on October 11, 2011 (EDT)
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That makes sense.  Thanks Jim.

4:54 p.m. on October 11, 2011 (EDT)
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You're welcome.  Let me know if you try it out.

HJ

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