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TIP: The online Bushwalk Inventory System can help bushwalkers with a variety of bushwalk planning tasks, including: Manage which items they take bushwalking so that they do not forget anything they might need, plan meals for their walks, and automatically compile food/fuel shopping lists (lists of consumables) required to make and cook the meals for each walk. It is particularly useful for planning for groups who share food or other items, but is also useful for individual walkers.Re: using upright canister stoves in the cold
Wed 31 Jul, 2013 9:14 am
Remember that the fill % makes no difference to the vapour pressure, it remains the same until all the liquid has changed to gas and then.... well then it's empty.
If a gauge is fitted then the vapour pressure for a given temp will remain constant as along as there is liquid present.
The fill % will only matter in the sense that there is a greater thermal mass in a full canister vs a half empty one and so the point at which gas stops flowing will happen quicker in the half empty one
If a gauge is fitted then the vapour pressure for a given temp will remain constant as along as there is liquid present.
The fill % will only matter in the sense that there is a greater thermal mass in a full canister vs a half empty one and so the point at which gas stops flowing will happen quicker in the half empty one
Re: using upright canister stoves in the cold
Wed 31 Jul, 2013 9:31 am
Re: using upright canister stoves in the cold
Wed 31 Jul, 2013 9:46 am
Scottyk wrote:Remember that the fill % makes no difference to the vapour pressure, it remains the same until all the liquid has changed to gas and then.... well then it's empty.
If a gauge is fitted then the vapour pressure for a given temp will remain constant as along as there is liquid present.
The fill % will only matter in the sense that there is a greater thermal mass in a full canister vs a half empty one and so the point at which gas stops flowing will happen quicker in the half empty one
It certainly does matter if the fuel is a mixture, which most of the bushwalking canisters are. Usually it's propane and either butane or isobutane or both, as well as small amounts of various other unspecified components. As you use a canister these fuels, being of different volatilities, are expelled at different rates. There's an article about this at backpackinglight.com that I believe Roger Caffin wrote or co-wrote. I'm not a BPL member so I have never read it but I'm fairly certain they make this point. Roger and I had a lively email discussion about this in 2005.
Here's an example of measurements I did in my kitchen about eight years ago. Steps: (1) weigh the canister; (2) immerse it in a water bath at 60°F; (3) wait for it to equilbrate; (4) measure the pressure with an attached gauge; (5) vent a quantity of fuel (burned remotely). Lather, rinse, repeat.
Re: using upright canister stoves in the cold
Wed 31 Jul, 2013 10:24 am
yep, you're correct, I forgot about the fact that they are blend.
My experience is with refrigerants and blended refrigerants will behave in this way also
You've obviously put quite a bit of time into this so i'll leave you to it.
My experience is with refrigerants and blended refrigerants will behave in this way also
You've obviously put quite a bit of time into this so i'll leave you to it.
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