How to make a flux ring?
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Gene .
(Tracker)

Locale: New England
How to make a flux ring? on 01/27/2007 18:59:46 MST Print View

I'm wondering if any of you have chosen to try and duplicate the 'flux ring' on the Jet Boil pots; on any of your previously owned pots/cups?

If so what material did they (JB)use? And what can I use?

Adhesives or weld?

Dwight Shackelford
(zydeholic) - F

Locale: San Francisco Bay Area
Re: How to make a flux ring? on 01/30/2007 08:22:57 MST Print View

Is this the heat exchanger you're talking about? The corrugated ring at the bottom of the cup?

I'll just assume it is, and run off at the mouth here.

Since its attached to the cup, and I think the cup is aluminum, it is probably aluminum too, to prevent dielectric corrosion.

Its going to be hard as hell to duplicate that ring's performance unless it is welded/bonded to the cup.

Another thing to look at is the heat exchanger ring put out by MSR. Though large, it is corrugated and clamps around the outside of the pot.

James Pitts
(jjpitts) - F

Locale: Midwest US
Re: How to make a flux ring? on 01/30/2007 08:49:32 MST Print View

I have put a LOT of thought into this and have decided... that I need to put a LOT more thought into this. I think making the ring would be fairly simple but attaching it to the bottom of the pot in such a way that you get good reliable heat conduction is another matter. I am left wondering if there aren't other ways to accomplish the same thing. In the end doesn't this just basically increase the surface area of the bottom of the pot that can capture heat?

That MSR heat exchanger clamps on. I am thinking that might be a good place to start, although the MSR setup is very bulky.

There was a person that posted here the other day about there "Jetboil" like setup. Certainly worth looking into.

I have this Jetboil pot and it does work well, although I have yet to do quantitative testing with my alcohol stove.

Bill Fornshell
(bfornshell) - MLife

Locale: Southern Texas
How to make a flux ring? on 01/30/2007 11:18:57 MST Print View

I made a couple of Flex Rings just after the JetBoil starting selling. Today you can just buy a pot with the flex ring made on it.

Home Made.



Buy a pot with the Flex Ring made as a part of it.

Woubeir (from Europe)
(Woubeir) - F - MLife
How to make a flux ring? on 01/30/2007 15:11:20 MST Print View

Bill,
nice design. I just wonder, how did you design this fluxring? I have been thinking about this since Jetboil came out whit this but my main problem is finding the right material (unbelievable how hard it is to find some materials overhere in Europe). I guess you start with a circular piece of aluminium flashing. What is the diameter of that piece and what is the diameter of the end result?

Gene .
(Tracker)

Locale: New England
Re: How to make a flux ring? on 02/02/2007 12:51:20 MST Print View

Looks like what I was asking about Bill. I too wonder if the first 2 photos, and the last; are'nt the same ring? The last one that looks burned, has some kind of edge around it's perimeter?

I wonder if the Jetboil pots are AL, as Dwight suggests the ring and pot are? I thought it was Ti?

Did you get the FedEx box I sent down a few weeks ago? I think I included a Brochure on a welding rod for AL in it. Is that a Cascades Design AL pot?

Tony Beasley
(tbeasley) - MLife

Locale: Pigeon House Mt from the Castle
How to make a flux ring on 02/05/2007 15:04:14 MST Print View

I have also been doing a lot of thinking about flux rings and I suspect that the flux ring has two purposes, the first is to improve the heat transfer by increasing the surface area of the pot that is in contact with the hot gasses and therefore transferring more of the heat to the pot and the second is to slow down the dwell time eg: the time the hot gases spend on the bottom of the pot therefore also transferring more heat to the pot.

As I understand the Jet boil pots are Aluminium, which has by far the best thermal conductivity of all of the materials used in backpacking pots, some initial testing which I have done to try and work out what is the best pot material has shown the this can also be a negative as while it is the best at transferring the heat from the flame it is also the best at loosing the heat from the sidewalls of the pot. Jet boil have over come this by insulating the pot with neoprene rubber.

Jet boil stoves have also increased efficiency by making the adjustable flow valve that does not allow the burn rate to be set to high. My testing has also shown that with all three main fuel stoves (canister white gas and alcohol stoves) that operating the stove at to high a burn rate is inefficient.

It is these three improvements that I think make the jet boil stove as efficient as they are.

Tony

Gene .
(Tracker)

Locale: New England
Re: How to make a flux ring on 02/06/2007 17:09:50 MST Print View

Good points Tony, along the lines of what I have been pondering for some time. Then insulating a Ti pot would'nt be as efficent if it does'nt lose heat from the sidewalls at the same rate?no not a new stove base it's a MOAB tailfin

Tony Beasley
(tbeasley) - MLife

Locale: Pigeon House Mt from the Castle
Re: How to make a flux ring on 02/06/2007 20:09:21 MST Print View

Hi Gene,

A good point. Insulation on a Ti pot would probably not have as great an improvement on efficiency as it has on Al pot but any side wall insulation would improve the efficiency of any pot at the more efficient burn rates. At less efficient high burn rate it is another story.

I have plans to do test what effect insulation has on a pot some time soon.

Tony

Adam Kilpatrick
(oysters) - MLife

Locale: South Australia
Insulating Ti Pots on 02/06/2007 21:20:48 MST Print View

Has anyone tried to make a neoprene insulative cover for a Ti pot/mug, like the new Firelite 500? Without a flux ring on the bottom will you just end up melting it with licking flames from the side?

Will be good to hear how you go Tony!

Brett .
(Brett1234) - F

Locale: CA
Adam, you just gave me an idea on 02/06/2007 21:27:34 MST Print View

..The snowpeak cups, such as the widely used 600ml, do not come with lids. A reflectix lid extending about 1" down the side of cup would serve as an insulated lid, and provide a little insulation without getting close to the flames. With a rubber band it could help to keep stuff in the cup. Ill try it soon.

Tony Beasley
(tbeasley) - MLife

Locale: Pigeon House Mt from the Castle
RE: Insulating Ti Pots on 02/06/2007 22:42:08 MST Print View

Hi Adam,

If the burn rate is not to high then the gasses coming up the sides are not that hot, below is graph of the temperature verses time (blue line) and the red line in the hot gas temperatre about 1cm from the pots side wall about 1.5cm from the bottom. note that the temperatre is only about 40ºC but at higher burn rates the temperature can get above 200ºC. Most insulations probably could cope with 40ºC
This test was boiling 500g water from 20ºC to 95ºC in about 12 minutes 20 seconds

Tony

Gas Temperature Graph

Brett .
(Brett1234) - F

Locale: CA
Tony/Adam, neoprene/reflectix lids.. on 02/06/2007 22:58:26 MST Print View

Tony, great test setup you have there; and very relevant info. Evidently reflectix can tolerate up to 82'C with no damage, and up to 121'C for 90 hours[1,2] so a reflectix lid could extend quite a ways down the exterior of a cup and theoretically decrease boiling times and decrease fuel consumption. I think we have figured out a useful application, and you certainly have the setup to verify it.
If the lower half of a cozy were designed to join the upper half/lid with no overlap, you've got a very light setup for simmer cooking in any size pot. Especially useful for tall (inefficient) pots such as the snowpeak mini solo.
As Adam suggested, neoprene would work also; its service temperature limit is 95C[3]

[1] http://www.reflectixinc.com/literature/technical/T62%20Reflectix%20DB1%20Technical%20Info.pdf
[2] http://www.reflectixinc.com/literature/technical/T20%20Hot%20Surface%20Performance%20C%20411.pdf
[3] http://www.mfa.org/_cameo/frontend/material_print.asp?name=neoprene&type=description

Edited by Brett1234 on 02/06/2007 23:28:09 MST.

Tony Beasley
(tbeasley) - MLife

Locale: Pigeon House Mt from the Castle
RE:Tony/Adam, neoprene/reflectix lids on 02/07/2007 01:58:12 MST Print View

Hi Brett,

Thankyou for the information on neoprene/reflectix and the compliment on my testing setup, I have spent several years setting it up and a lot of money,it has been financed out of my own pocket as is the stoves and canisters that I use, although some of the equipment/computers are old discarded equipment that I have been lucky enough to acquire or borrow. Time is my biggest problem at the moment with my testing and development program.

I have not heard of reflectix before I will see if it is available in Aus it sounds as if it is interesting insulation, neoprene is heavy and it adds quite a bit of weight to the jet boil pot which is one reason the UL people do not like the Jet boil that much especially for short walks. Jet Boil stoves have just become available here in Australia and I hope to purchase one soon, I think that they are a great little stove which has progressed the design of backpacking stoves more than any stove has for a long time.

Tony

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: RE:Tony/Adam, neoprene/reflectix lids on 02/07/2007 02:23:32 MST Print View

Hi Tony

> Jet Boil stoves have just become available here in Australia and I hope to purchase one soon, I think that they are a great little stove which has progressed the design of backpacking stoves more than any stove has for a long time.

Ah ... read the reviews.
They are very heavy, lack power (by design), die totally in the snow, and only work well with new isobutane canisters on warm days. Yes, they are more efficient, but do the maths and work out what the real weight savings in fuel are and what duration trip would actually justify the extra weight (and cost) of the heavy stove plus heavy pot over something like a Snow Peak GS100 and an AGG 2 qt pot or an MSR Titan 1.5 L pot.
Note that the package weight they quote is usually for a 100 g canister, not a 220 g canister.
(These comments are based on my experiences and do not reflect any official BPL position.)

Brett .
(Brett1234) - F

Locale: CA
Tony, you are welcome on 02/07/2007 02:44:22 MST Print View

Reflectix is a radiant barrier which is commonly used in the backpacking community in cozys, such as by www.antigravitygear.com
Our discussion started with lids for cups and other pots; the jetboil is already insulated, and might not benefit much by reflectix. With all due respect to Roger, yes, do read the reviews on the jetboil. It has all the limitations of a canister stove naturally, but there are reasons it is a popular stove among the lightweight crowd (not the UL crowd?) I have a jetboil, and every guy I've hiked with lately wants one as well after seeing it in operation. I can have a hot drinks for 4 people three minutes after taking it out of my pack; while holding it in my hand if necessary at a rest stop. As Roger mentioned, it is 'low power', lower BTU output than other stoves. That is by design. It is a tradeoff of speed and fuel consumption. There is no reason to pump out more BTUs than the flux ring can absorb. I think they dialed in the BTUs well, since I can literally hold the metal ring below the neoprene while the stove is running.

Tony Beasley
(tbeasley) - MLife

Locale: Pigeon House Mt from the Castle
Re: RE:Tony/Adam, neoprene/reflectix lids on 02/07/2007 03:22:45 MST Print View

Hi Roger,

Of course I have read the reviews on Jetboil stoves and I understand the negatives about weight and the problems with upright canisters stoves in cold weather but all stoves have there good and bad points, I still think that they are a great stove and Jetboil have made other manufacturers look at their designs.

I also currently use a much lighter stove pot system MSR Pocket Rocket and a Snowpeak Ti pot but it is not perfect does not work in the cold and has very poor efficiency in the wind, as Brett has mentioned the Jetboil is a quick easy to use stove in a fairly large range of conditions.

Tony

Gene .
(Tracker)

Locale: New England
Re: Re: How to make a flux ring on 02/07/2007 10:39:55 MST Print View

Tony, you and Brett made some relevant commnets here that sparked an idea in my mind.

What if we constructed an 'upside down' cozy for cup or pots from Reflextix (aluminized bubble wrap)? My idea is that it could serve as the lid, upside down on the pot or cup; and when 'right side up' placed on the cup or pot removed from the heat. Cut a slit in the side for any handles.

Also, I noticed a foam sheet product at a local craft store called, 'Foamtastic' from www.nicolecrafts.com, in a 9" x 12" x 1/8th" +/- thick for .49cents. Not sure of any of it's other qualities other than it's waterproof, seems like it would be insulative though.

Tony Beasley
(tbeasley) - MLife

Locale: Pigeon House Mt from the Castle
Re: How to make a flux ring on 02/07/2007 17:20:50 MST Print View

Hi Gene,

I like your idea of a reversible cosy/lid it solves two problems with one cosy.

I was reading an article last night in yesterday’s local paper about how our historic High Country Huts are burning down due to the high incidents of drought fuelled bushfires that we are currently experiencing. The High country Rangers are experimenting when a fire is nearby they wrap the huts in what we call sarking a form of heavy duty foil insulation for houses to try and save them. For some time I have been thinking about a light weight pot insulation idea and reading the BPL forum and reading the Huts article has helped me with an idea

I have been thinking for some time of a design some thing like your upside down cosy but with a small modification instead of having a tight fitting side why not have it loose fitting with about half inch (12.7mm) clearance to trap the hot gasses around the pot. See picture below, this is a pot lid side wall insulation cover that I made this morning out of Aluminium foil and it weights 6.6g (0.23oz). I have not tested this idea yet.

pot insulation

Tony Beasley
(tbeasley) - MLife

Locale: Pigeon House Mt from the Castle
re: How to make a flux ring on 02/07/2007 17:24:24 MST Print View

Sorry wrong picture came through try this one

Tony

Pot insulation picture