Stoves: How to measure fuel usage?

[LeeF]

I have, without a doubt, the coolest professor in the history of night school; she is allowing me to do a research paper on backpacking stoves. It will be in the compare and contrast format with the Trangia Mini 28 verses a MSR Whisperlite International.

First weighing each component and accessory of both stoves was
educational. The Trangia burner alone is barely over two ounces; it's the simmer ring and cap that add too much weight. The MSR is a brick. I can't believe I've been packing that thing all these years.

Then timing the boil with a thermometer was even more of a shock. In four seperate tests on two different days the Trangia 28 boiled 16 oz. of water in less than six minutes. This is very different from the published ten to twelve minute figures. The MSR varied from 3.75 minutes to 4.25 minutes, which I suspect was the fuel level in the bottle and the amount of pressure.

Here's the question: What is the accepted method of measuring fuel usage with a MSR Whisperlite type stove? Do you fill the fuel bottle to the stated capacity, always pump 20 times for consistant pressure and then start? I did figure out to use a measured amount of fuel for priming and not attempt to fill the pan from the bottle each time. Then you have to remember to add back in the priming fuel. I believe the actual amount of fuel used is going to vary for every boil depending on pressure and fuel. That's a lot of variables to calculate.

Measuring the Trangia was simple. Put 1 oz. of fuel in the stove, light, boil, and extinguish. Then pour out the remaining fuel and measure it.

Thanks.

[Dances with Mice]

... Here's the question: What is the accepted method of measuring fuel usage with a MSR Whisperlite type stove? Do you fill the fuel bottle to the stated capacity, always pump 20 times for consistant pressure and then start? I did figure out to use a measured amount of fuel for priming and not attempt to fill the pan from the bottle each time. Then you have to remember to add back in the priming fuel. I believe the actual amount of fuel used is going to vary for every boil depending on pressure and fuel. That's a lot of variables to calculate. ... Just talking in general rather than specifics: Don't get hung up on lab conditions. Just pretend you're on a hike and use the stoves the way you or anyone else would. Start with the bottle full and do a series of tests (boils), adding pressure when needed. Same with the Trangia - on a hike I'd start with it full then use it a couple of times before refilling it.

Can you weigh the fuel bottle accurately enough to measure the amount of fuel used after each burn? That way you don't have to open and depressurize the fuel bottle after each test. Or you can do a predetermined number of burns in series (3, 5, 10, 15, whatever) then measure the amount of fuel consumed and calculate the average amount used per burn.

[atraildreamer]

I think that it may be of use to your project. :-?

http://www.whiteblaze.net/forum/showthread.php?t=19616

[rafe]

For my Whisperlite, many years ago, I just filled the bottle with a known amount of white gas. Primed it, lit it, set it to a useable flame, and timed how long it ran before running out. I think I got something like 5 hours of burn time from 16 oz. of fuel. With an alky stove, it's a whole 'nother situation.

With my (new) canister stoves, the procedure is this:
1. Weigh burner unit + canister on electronic scale (measures to 0.1 oz.)
2. Note weight before burn.
3. Burn
4. Note weight after burn.

Basically, with the canister, I see a drop of about 0.1 oz for each cup of water heated to boiling.

[SGT Rock]

Here's the question: What is the accepted method of measuring fuel usage with a MSR Whisperlite type stove? Do you fill the fuel bottle to the stated capacity, always pump 20 times for consistant pressure and then start? I did figure out to use a measured amount of fuel for priming and not attempt to fill the pan from the bottle each time. Then you have to remember to add back in the priming fuel. I believe the actual amount of fuel used is going to vary for every boil depending on pressure and fuel. That's a lot of variables to calculate.

Ive test a lot of stoves over the years. For this type I normally put in a certain amount, say 4 ounces (no need to fill it all the way) and then conducted burns to boil. I assume you are using a pint of water for each boil and using the same pot and conditions of the pot for each test. What are you using to measure temp?

Anyway. What I liked to do with stoves like the MSR whisperlite and the Trainga was fill-em up and then see what happened over time with each boil. At the end of each boil I shut off the stove and measured the system (in grams for better accuracy) until I got to the end of the fuel. But before I started I determined what boil temp would be using elevation and barometric pressure. I also liked to chart how fast each stove got to certain points along the temperature range - usually 100F, 125F 150F 200F and boil.

Another cool thing to try is comparing the MSR to itself when you run it at full throttle, 3/4 throttle, 1/2 throttle, and 1/4 throttle. The differences in fuel consumption to achive the same results is also interesting.

Another couple of cool things to try: aluminum pot vs titanium pot of the same size. Try pot with lid on vs pot with lid off. Also you may want to try the pot blackening thing that is often reccomended too.

Then to top it off, try building some stoves of your own.

Have fun. You may get hooked.

[LeeF]

Thanks to each of you. I can definately use the pointers.

I've been using a good kitchen scale to weigh the components, a thermometer to measure the water temperature start to finish, the same pot and lid for both stoves, and a volume measurement with one cc increments.

I'll probably keep this experiment limited in scope because after I turn in the paper I'll have to defend the findings in a cross examination. Later I want to add in all the variables of multiple throttle settings, fuel levels, and pressure levels for my own knowledge.

I'm afraid the make your own stove disease has already infected me. Right now the counter top is covered with half a dozen pepsi can stoves (three sizes, with and without wicks), several cat stoves, and a couple of firelight models. I'm into my second quart of denatured alcohol and well into a quart of 91% iso. I'm burning more fuel building and testing stoves than actually camping.

[Skidsteer]

Yep, you're in trouble. ;)

[bigcranky]

You are in serious trouble. Here's a quote from a field guide to backpackers:

"But the most hard core of the Gearheads are beyond any human help. I am speaking, of course, about the legendary Stoveheads. Yes, these people do exist. Their secret rituals -- involving fire and the boiling of 2 cups of water, over and over while taking detailed notes – are the stuff of science fiction, but I assure you, they are real. They are real.

The true, unredeemable Stovehead has multiples of every kind of backpacking stove made today, along with stoves long out of production that he (and they are almost all male) thinks are ‘neat.’ It’s not uncommon to find three or four white gas stoves, and a lightweight canister stove or two, but the most reliable field mark of the true Stovehead is his collection of homemade alcohol stoves. Sure, you might see a commercial stove, maybe a Brasslite or Varga, but his spoor will almost certainly include a large pile of homemade stoves, and aluminum cans, and metal tape, and JB Weld secreted in the inner sanctum of the true Stovehead.

Most of the major problems involving Stoveheads are social – they tend to be incredibly boring at parties, and any guest drinking from an unusual can is constantly pestered until he gives up the ‘dead soldier’, undamaged and ready for the experimental chamber."

Welcome to the dark side....

[LIhikers]

Here's what I do for keeping track of fuel used in my MSR simmrlite stove. I fill the bottle with fuel in preperation for my wife and I to go out for a multiday backpacking outing. Then I keep track of how many times we use the stove during that trip. Then when we get home I put our gear away and forget to measure the remaining fuel and how many times we used the stove. Then when we get ready for the next trip I repeat the process :)

[LeeF]

LIhikers,
I've had my MSR 15+ years and can honestly say I don't know how much fuel it uses either. Just like you, I fill up the bottle before a section hike and forget all about measuring the remaining fuel when I get home to a hot shower and warm bed. By the time I've sun dried my sleeping bag and wiped out the tent/hammock I'm ready to put the gear away until the next trip.

I've never run the big bottle dry even on trips over a week long. Just like toothpaste in the bottom of the tube there always seems to be a little fuel left down in there. You just have to pump it a few more times. Now that I have the new 11 oz bottle I believe I'll run out somewhere and it will be on a rainy day for sure.

I should offer to create a new brochure for MSR!
-Fuel usage is so little you can't measure it!
-Will operate on fumes for days!
-Will go years without running out of fuel

[rafe]

LeeF, that is exactly my experience with the Whisperlite, and why I'm clueless and nervous about alcohol and canister stoves. Over the last decade or so, all my section hikes have been short enough so that the 22 oz. gas canister is more than enough. And when I wasn't using the MSR, I was using a Zip stove. :) I simply haven't had to deal with the issue of fuel-resupply since... oh... 1990 or so.