Jet Boil Cup

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oops56
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Re: Jet Boil Cup

Post by oops56 » Wed Sep 26, 2007 2:57 pm

I dont have a complete jet boil just that cup that ring does not come of the cup does it have not look at it that close i take a look.
Man play with fire man get burnt

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zelph
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Re: Jet Boil Cup

Post by zelph » Wed Sep 26, 2007 3:02 pm

oops56 wrote:I dont have a complete jet boil just that cup that ring does not come of the cup does it have not look at it that close i take a look.

Take a look at these photos, looks like the ring comes off:

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http://www.woodgaz-stove.com/

oops56
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Re: Jet Boil Cup

Post by oops56 » Wed Sep 26, 2007 5:40 pm

Yep it comes off so Xmas coming its spot weld a little got it off but the fins are on the cup no good like that.
I am done on this jet boil i got the stove that works on it this is the end. Now this new little stove i get 11 to 12 min. burn on 1/2 oz. did not do a water test yet i filled the kettle to the top to see when it started to boil at 8 min. think the kettle holds 24 oz. not sure more testing later.Its hot out there 84F.
Man play with fire man get burnt

Tony
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Re: Jet Boil Cup

Post by Tony » Mon Oct 15, 2007 9:14 pm

Hi All,

The ring does come off the JB pot

I have been playing around with a JB pot with the location ring cut off and on a E2E Gram weenie stove I am not getting as good efficiency as a normal pot of similar size (I have not recorded figures to publish as I am just playing around), I believe this is because alky stoves require a good air flow to work properly and the flux ring on the JB pot slows this air flow down.

I have been testing canister stoves for several years now and recently I purchased a JetBoil stove with both the 1l pot and 1.5l pot and I have run test on the JB with both pots. The best results that I have ever recorded are with a JetBoil stove with the JB 1,5l pot. The stove was turned on full open or flat out and I boiled 0.5l (2.11 US cups) water from 21.5ºC (70.7ºF) to 95ºC (203ºF) in 2 minutes 30 seconds and I used 4g (0.141 oz)of fuel. The 1l JB pot is not that much less efficient. Normally with my Pocket Rocket I use nearly twice that amount even on the most efficient settings.

Tony

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zelph
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Re: Jet Boil Cup

Post by zelph » Mon Oct 15, 2007 10:23 pm

Tony wrote:Hi All,

The ring does come off the JB pot

I have been playing around with a JB pot with the location ring cut off and on a E2E Gram weenie stove I am not getting as good efficiency as a normal pot of similar size (I have not recorded figures to publish as I am just playing around), I believe this is because alky stoves require a good air flow to work properly and the flux ring on the JB pot slows this air flow down.

I have been testing canister stoves for several years now and recently I purchased a JetBoil stove with both the 1l pot and 1.5l pot and I have run test on the JB with both pots. The best results that I have ever recorded are with a JetBoil stove with the JB 1,5l pot. The stove was turned on full open or flat out and I boiled 0.5l (2.11 US cups) water from 21.5ºC (70.7ºF) to 95ºC (203ºF) in 2 minutes 30 seconds and I used 4g (0.141 oz)of fuel. The 1l JB pot is not that much less efficient. Normally with my Pocket Rocket I use nearly twice that amount even on the most efficient settings.

Tony
Hi tony, glad you stopped in. Thanks for sharing your test results.

The JB sure is an amazing system. The flux ring has cought my interest since it first came out. Catch all the heat that you can.
The best results that I have ever recorded are with a JetBoil stove with the JB 1,5l pot.
That is really awesome heating power.

I thought for sure the JB pot would be more efficient than a regular of the same size. Maybe some day you can try a different burner under the JB pot with flux ring. Most people say they don't want the flames going up the sides of the pot. If the flux ring slows down the air flow, does that mean it keeps the flames under the pot?

My experience has only been with alcohol stoves, no canister. (also passive wood stoves)
http://www.woodgaz-stove.com/

Tony
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Re: Jet Boil Cup

Post by Tony » Tue Oct 16, 2007 12:23 am

Hi Zelph,
My experience has only been with alcohol stoves, no canister. (also passive wood stoves)
I have followed your work on another forum.

I have just started to play with alcohol stoves, they are much easier and faster to make than canister stoves.

I am currently developing a sub 30g (1.05oz) stove and pot, will post on bplite when I finish.

Tony

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zelph
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Re: Jet Boil Cup

Post by zelph » Tue Oct 16, 2007 10:38 am

Tony wrote:Hi Zelph,


I have just started to play with alcohol stoves, they are much easier and faster to make than canister stoves.

I am currently developing a sub 30g (1.05oz) stove and pot, will post on bplite when I finish.

Tony
Great!!! We look forward to your success. Stove and Pot, that is interesting, :idea: :?:
http://www.woodgaz-stove.com/

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zelph
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Re: Jet Boil Cup

Post by zelph » Tue Oct 16, 2007 9:24 pm

Tony wrote:Hi All,

The ring does come off the JB pot

I have been playing around with a JB pot with the location ring cut off and on a E2E Gram weenie stove I am not getting as good efficiency as a normal pot of similar size (I have not recorded figures to publish as I am just playing around), I believe this is because alky stoves require a good air flow to work properly and the flux ring on the JB pot slows this air flow down.

I have been testing canister stoves for several years now and recently I purchased a JetBoil stove with both the 1l pot and 1.5l pot and I have run test on the JB with both pots. The best results that I have ever recorded are with a JetBoil stove with the JB 1,5l pot. The stove was turned on full open or flat out and I boiled 0.5l (2.11 US cups) water from 21.5ºC (70.7ºF) to 95ºC (203ºF) in 2 minutes 30 seconds and I used 4g (0.141 oz)of fuel. The 1l JB pot is not that much less efficient. Normally with my Pocket Rocket I use nearly twice that amount even on the most efficient settings.

Tony
Hey Tony, today I read on another forum that the Jet boil performance changes quite a bit when the canister is under half full. Have you found that to be true :?: Is that true to other canister stoves as well :?:
http://www.woodgaz-stove.com/

Tony
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Re: Jet Boil Cup

Post by Tony » Wed Oct 17, 2007 2:28 am

Hi Zelph,
Hey Tony, today I read on another forum that the Jet boil performance changes quite a bit when the canister is under half full. Have you found that to be true Is that true to other canister stoves as well
The pressures inside a canister can be complex it depends on the gas mixture, volume and temperature and latent heat of evaporation also has to be taken into account. If the canister is being used at warmer temperatures eg 20ºC (70ºF) where I do most of my testing I do not believe that the performance of the JetBoil or any other canister stove operated at an efficient setting would decrease as the canister was emptied, though for most canister stoves a at high burn rate the latent heat of evaporation does cause the pressure to drop in the canister but the JetBoil has a flow restrictor in the valve that lessens this problem. I mostly use nearly empty canisters for my tests and I have not noticed a decrease in performance. I will run some tests soon.

JetBoil’s do not have a good reputation in the cold which is another story and is best answered by reading this excellent article on this site about canister mixtures/pressures
http://www.bushwalking.org.au/FAQ/FAQ_Mixtures.htm

These are some pictures of my JetBoil which has been modified to be a liquid feed stove working at -7.5ºC (18.5ºF)

I would like to read what was written on the other forum if you could link me to it.

BTW I like the bplite site

Tony
Image
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zelph
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Re: Jet Boil Cup

Post by zelph » Wed Oct 17, 2007 10:54 am

Tony wrote:Hi Zelph,
JetBoil’s do not have a good reputation in the cold which is another story and is best answered by reading this excellent article on this site about canister mixtures/pressures
http://www.bushwalking.org.au/FAQ/FAQ_Mixtures.htm

These are some pictures of my JetBoil which has been modified to be a liquid feed stove working at -7.5ºC (18.5ºF)

I would like to read what was written on the other forum if you could link me to it.

BTW I like the bplite site

Tony
Image
Image
The article is excelent Tony. This part is quoted from it:
The solid blue curve shows the actual pressure as a function of the amount of mixture left inside the canister. This pressure falls as the amount of mixture left in the canister falls. Note especially that the ratio of gases in this mix is changing as gas is drawn off: the amount of propane left is falling.

The faint blue dotted line (joining the blue curve at the right) shows what the gas pressure would be if the liquid in the canister was pure butane: it is a constant of course. It may actually be misleading to draw it as a line across the graph, but never mind.

The dashed green line represents atmospheric pressure at 3000 m. OK, we don't get that high in Australia, but never mind. It too is really independent of the horizontal axis.


Now, what can we tell from this graph? We can see that initially the canister pressure (blue curve) will be above the surrounding atmospheric pressure (green dashes), so gas will come out when you open the valve: a mix of butane and propane. So the canister will be losing both propane and butane. But the propane is 'boiling', while the butane is merely 'steaming', so the propane is coming off at a faster rate than the butane. This means that the concentration of propane remaining in the liquid will fall fairly fast. And as the concentration of propane falls, so does the total vapour pressure. Eventually, as you can see, the VP of the fuel (blue curve) falls below one atmosphere (dashed green line), at which point the canister will stop giving off gas. The stove goes out - even though the canister may still be half full (or more). This has happened to many people in the snow.

Not considered here is the fact that as the fuel evaporates inside the canister the remaining liquid fuel is losing energy and getting colder. This imply makes the sitaution even worse of course: the pressure inside the canister will be even lower. You can see what can happen in the marvelous picture here of an iced up Snow peak stove. The stove is burning all right, but in a little while it will go out when all the propane has been used up.
Nice photos of your JB modified to liquid feed. Does liquid feeding eliminate the problems that we read of in the above quote?

I'll go fetch the info from the other forum for you and post in this thread.

Thanks for your very informative insight to the operation of the JetBoil.
http://www.woodgaz-stove.com/

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