Gas Usage

[dlovett]

Hey for next weekend, I am going to bring my stove and pot so I can heat up some water for some huel meals if needed during the night.

My only jetboil jetpower isobutane/propane canister is listed as 100g of fuel and currently weighs 170g. I believe they are approx 100g empty, so I'm assuming I have a good 50g of gas.

Does anybody know very approximately how many grams of gas an Alpkit Krauku would burn to heat up 250ml of water in a ti mug and approx how long it might take in 5-15c air temp? I'm guessing I should be good for three uses during the event, but can anybody could confirm this for me?

Can't remember the last time I used it, but just just fired up and seemed ok.

TIA

Duncan

[Bearbonesnorm]

I don't think you're probably far off the mark Duncan.

[dlovett]

Ta Stu, the only stats I can find on the internet (trust them at my peril!) say 2.3/2.4g per min on full power and 2m 30s to boil 350ml.

Assuming that's all correct and conservatively allowing for 2.5g of gas per minute I should have enough for boiling almost 3l, which will be far more than the 750ml - 1lt I will need.

I might have to add some hot chocolate sachets into my food bag.

[dlovett]

To answer my own question, now I'm happy I have plenty of gas, 300ml boiled in just under 2.5mins on about 3/4 power. Full power was far to much for my 650ml mug and flames were going round the side. Total used 4g of gas, so I should have about double the amount I'll need next weekend. Might have to open a pop up noodle bar enroute!!

IMG_0511.jpg (70.69 KiB) Viewed 536 times

[whitestone]

Duncan, if you have a look on YouTube for a channel named "Gear Skeptic" he did a couple of videos on stove efficiency rather than outright speed. Actually I'm sure I've posted recently about them, he's really geeky . Basically having the stove set low enough that the flames aren't lapping up the side of the container is most efficient. Apparently having a lid makes little to no difference, talking tenths of a gramme here at most.

I'm going to be taking a beer can meths stove and will probably knock up some couscous at some point - the Ainsley Harriott sachets are perfect for boil in the bag (sachet) - the supermarket own-brand ones are just as good.

[dlovett]

Yep I did turn it down a bit after the photo. Forgotten how fast and powerful the little bugger is.

I've a few bags made up of Huel Mac and Cheese as it's one that actually seems to agree with my stomach and is pretty loaded with cals/carbs/protein etc. I normally wouldn't bother with the mug pack, but the lack of options suggest a couple of quick hot meals might well be a good idea. I should be able to keep it under ten minutes from stopping (unpacking, heating, eating, packing) to get going again.

Some of this coconut milk powder mixed with hot chocolate powder should also add some cals.

https://www.sainsburys.co.uk/gol-ui/pro ... lsrc=aw.ds

[dlovett]

Duncan, if you have a look on YouTube for a channel named "Gear Skeptic" he did a couple of videos on stove efficiency rather than outright speed. Actually I'm sure I've posted recently about them, he's really geeky . Basically having the stove set low enough that the flames aren't lapping up the side of the container is most efficient. Apparently having a lid makes little to no difference, talking tenths of a gramme here at most.

Wow, just watching

Backpacking Stove Efficiency, Part 1: Pot Diameter, Burner Size, Flame Level

He is seriously thorough.

[thenorthwind]

Worth pointing out that wind makes a massive difference to how much gas you use IME. But I would feel perfectly comfortable taking a half full* canister for 3 brews, and I get anxious if I'm not confident of getting coffee in the morning

*if it were half empty I'd be worried though

[dlovett]

So you don't need to spend 40 minutes watching the video...

He recommends a small stove on low and small mug with no lid as the most weight efficient. A small stove on low and wider pan with lid as the most gas efficient. The gas difference was approx 1 extra boil per 100g canister between the low weight/high weight (60g) difference. I might actually not take my pot lid and instead just use a tin foil lid as he suggests to save the weight of an extra choco bar!!

Of course taking the wind shield will bugger that all up, but as thenorthwind says, it makes a big difference outside and it clips round my mug nicely.

Hopefully that now means everybody knows what to bring for the weekend!!!

[Rasta]

It is easy - Put your hand a couple of inches above the pot when it is being heated. If you feel heat (not just warmth) coming up the sides, then that is heat wasted. Just heating air. Admittedly also a bit of the sides, but mostly wasted.

Turn the gas down until that heat up the sides is minimal. Takes longer to boil but uses less gas.

[frenchbikepacker07]

Hey Duncan,

Sounds like a cool plan for the weekend! To answer your question:

Fuel Use: It's a bit tricky to give a super exact number, but most of the time, for boiling 250ml of water in those temperatures, you're probably looking at around 5-10g of fuel. If you've got about 50g left, you should be able to boil water at least 5 times, give or take.

Time: With your Alpkit Kraku, expect somewhere between 2.5 to 4 minutes to get that water boiling in those temps. Again, just a ballpark figure, might vary a bit depending on conditions.

So yeah, you should be more than good for three uses over the event. But like always, keep an eye on it or maybe have a bit of backup if you can. Have an vaguely exciting trip!

Cheers,
Alan

[Boab]

What you need, is one of Stu's Ti-Mag Windshields. Or just eat cold pasties, while pushing up another bastard hill, all night like the rest of us.

[dlovett]

What you need, is one of Stu's Ti-Mag Windshields. Or just eat cold pasties, while pushing up another bastard hill, all night like the rest of us.

Yep I have a very similar one to that. I will have some snacks, but I have found it only takes ten mins stop to start and I can lube chain, check pads, adjust bags etc whilst that's happening so it's not dead time.