It's like watching "ER". I can almost feel the cuts.
What we need is a webcam. ;-)>

I have heard similar re. vaporizing temperatures (MM's observation). I also think a longer preheating tube would only make the unit more fragile.

Edited by kdesign on 11/15/2005 10:26:35 MST.

What I would love to see is the interior of the control valve. Is this just a standard needle valve?

Bill: have you thought of making up a small plastic substitute for the magnesium 'head'? Lightweight, but much easier to handle. It won't be melting. It would also locate the canister neck.

What does the black control knob weigh? It should be possible to make a UL T-bar replacement?

Roger Asked:
Q1 - What I would love to see is the interior of the control valve. Is this just a standard needle valve?
A1 - Is this what you are asking about?


Q2 - Bill: have you thought of making up a small plastic substitute for the magnesium 'head'? Lightweight, but much easier to handle. It won't be melting. It would also locate the canister neck.
A2 -Yes, but. The "head" weighs 39.6gr/1.4oz. (knob removed). I will drill it out and remove as much metal as I can first. I hope to reduce enough weight that making a substitute would not be worth the time. I would like to retain the ability to hold the canister connector and valve assembly with a much reduced stock unit.

Q3 - What does the black control knob weigh? It should be possible to make a UL T-bar replacement?
A3 - The black knob weighs 8gr/0.28oz. I will first drill some holes in the knob and see how much weight I can reduce that way. I agree that a replacement could be made. If I can reduce the weigh by half I may keep the knob.

I found out today much trouble it can be to drop 3.6gr/0.13oz. I was able to remove the Hose from the Valve & Hose Assembly. The braided SS line has a black tube something in it that looks a little like filter material. I cut the braided line in half leaving it 3" long. Anyway, it was far more trouble than it was worth.




My local Hot Rod shop gave me a little help by cutting the line with a really neat piece of equipment. They custom make a lot of Stainless Steel lines and couldn't believe I would do all that work to save 3.6gr. I reminded them that some of what they did to their cars is also very time intensive. They have just returned from the Bonneville Salt Flats and a speed record attempt for there class. I just asked them if they used a check list and how many times did they go over it before each run.
They have a really nice milling machine and I might use it to remove material from the Valve Casing. I will have to make a chuck to hold the casing first. I may be able to do it with a flex shaft on a drill but I still need to mount it on something.

Edited by bfornshell on 11/16/2005 20:21:45 MST.

Hi Bill-

Nice photos as usual!

Can you tell if there is anything interesting in the fitting between the braided tube and the solid tube? I've always wondered if the wire inside the solid tube performs some kind of valving or throttling function with how it mates with the fitting. I'm thinking it *might* work as a 1 way valve to temporarily shut off the fuel supply if the pressure in the preheat tube got high for some reason.

Edited by MikeMartin on 11/16/2005 21:51:01 MST.

> Q1 - What I would love to see is the interior of the control valve. Is this just a standard needle valve?
> A1 - Is this what you are asking about?
Yep, thanks.
OK, standard needle valve. Hum - interesting. Thoughts which follow:

The needle valve is valving liquid. Consistent with performance. So liquid is going up the tube to the stove. It vaporises up there.

Other remote cartridge stoves are similar, but withOUT the big wire up a straight bit, and they work. I think the wire is simply an attempt at a heat exchanger, feeding back from the burner. Since other stoves don't have one, ...

Other stoves, like the Snow Peak GS200D, can be used with liquid feed. They do NOT have a massive lump of metal around the valve. So I think the beautiful finned diecast magnesium housing has the following functions: something to hold when you are mating the canister to the valve; something to protect the plastic clip which holds the canister; a stylish bit of marketing. Deduction from all this: you could safely leave the whole magnesium bit off. (I think ...)

Apropos of other remote-cartridge stoves: I think it should be possible to make a stand which will hold a conventional cartridge in an inverted position so the valve can be easily adjusted. This means any remote-canister stove could be used. I will experiment, and report.

How did you get the pictures into the email???? If I succeed with the above, I may be able to post a pic of it.

Mike asked:
Q1 - Can you tell if there is anything interesting in the fitting between the braided tube and the solid tube?
A1 - This looks like a standard "crimp" used to connect a tube and a braided hose. Remember the black (whatever) that is inside the hose. It looks sort of like a filter material, somewhat like the old style cigarette filter. A Coleman enginner said this material helps slow down or regulate the gas flow. I hope to get a call from him sometime next week. He was given BPL web URL to have a look at what we are doing. When you measure the brass rod that goes into the brass tube part of the hose and measure where the black stuff starts in the braided part of the line there doesn't seem to be any space for something else.

Q2 - I've always wondered if the wire inside the solid tube performs some kind of valving or throttling function with how it mates with the fitting. I'm thinking it *might* work as a 1 way valve to temporarily shut off the fuel supply if the pressure in the preheat tube got high for some reason.
A2 - Heres is what I know about that brass rod:
- It is 3-5/8"+ a very small amount long.
- It is the same size (1/16") as BPL Ti rod.
- It weighs 1.9gr
- It slides freely in and out of the brass tubing connected to the braided SS hose.
- It will slide into the brass fitting that the pre-heat loop tube is connected to about 3/8".
- Gas pressure from the canister will move the brass rod, case in point, when the gas pressure blew the brass rod out of the end of the brass tube part.
-- When the pre-heat tube is "hot" how much do you think the brass rod might expand? If the brass expanded it might act as some type of flow control.

Roger Said:
[1- R] Other stoves, like the Snow Peak GS200D, can be used with liquid feed. They do NOT have a massive lump of metal around the valve. So I think the beautiful finned diecast magnesium housing has the following functions:
1- something to hold when you are mating the canister to the valve;
2- something to protect the plastic clip which holds the canister;
3- a stylish bit of marketing.

[1-B] I agree.

[2-R] Deduction from all this: you could safely leave the whole magnesium bit off. (I think ...)

[2-B] In warm weather I think your idea would work. For use in very cold weather I don't think I would remove it.

Q-How did you get the pictures into the email?
A- You need to upload your pictures to a site such as Photobucket.com. They then provide the link to BPL.com or other places on the web. You do a copy/paste of their URL from Photobucket to BPL.com. Photobucket is a free hosting service for 500 plus pictures.

Edited by bfornshell on 11/17/2005 07:54:57 MST.

> 2-B] In warm weather I think your idea would work. For use in very cold weather I don't think I would remove it.

Needs testing. But I have used other remote canister stoves like the Snow peak GS 200D in the cold. Light carefully, at low setting, so the preheat tube warms up without a fireball.

Question: I have lost the URL you gave somewhere to your blog with the balloon airbed. Can you repeat? Please!

Roger writes:

>> The needle valve is valving liquid....So liquid is going up the tube to the stove. It vaporises up there.

Roger, at full flame, in cold weather, I definitely agree with you. But at a low-heat valve setting, say at startup, or during a low-heat simmer, there would be a larger pressure drop right at the valve. Especially in warm weather, I expect some (all?) of the fuel might vaporize just downstream of the valve due to this drop.

If this were true, the fins would serve to conduct heat from the outside air into the evaporating fuel, providing the necessary heat of vaporization.

From a design standpoint, I think this would be desirable during startup where the pre-heat tube is still cool. The fuel still needs to vaporize before it reaches the jet to mix with the air, and the fins would help this process -- reducing the chance of a fireball, as you say. Also, during low-heat simmering, it may be advantageous for the fuel to vaporize right at the valve to allow better flame control and reduce sputtering. (Both of these issues are probably irrelevant for full-throttle Winter snow melting.)

If a mixed-phase fuel were sometimes present in the fuel line upstream of the pre-heat tube, it might offer an explanation for the "wire" and "filter material" in the fuel line. Both of these mystery components might serve to smooth out the flow of a mixed-phase fuel to reduce burping and sputtering.

All of this is sheer speculation, of course. What we need is a transparent fuel tube so we could watch the fuel vaporize on it's way to the burner...

Cheers,

-Mike

Edited by MikeMartin on 11/17/2005 16:22:04 MST.

Roger:
Here is the URL for the Poly-Tube DAM stuff. It is on 4 different pages. If you look at the top of the page you will see "SEARCH THIS BLOG". Click there and it will take you to a list of the other pages. It is long and drawn out. This was a collection of posts/questions/answers that ran about a year.

DAM Blog

> Especially in warm weather, I expect some (all?) of the fuel might vaporize just downstream of the valve due to this drop.
To be sure, it would.

> If this were true, the fins would serve to conduct heat from the outside air into the evaporating fuel, providing the necessary heat of vaporization.
Good theory, but I suspect the amount of energy input via the mag block would be small. The canister would do just fine imho. After all, upright stoves do work in 'warm' weather'.

> From a design standpoint, I think this would be desirable during startup where the pre-heat tube is still cool.
But the whole fuel line and burner have heat capacity, and would warm the fuel far better, and once the flame is there, who needs any other heat source?
This works with other stoves.

Yeah, a clear tube might be interesting - but then it would have a different thermal mass. Hum.
More playing needed.

>> Good theory, but I suspect the amount of energy input via the mag block would be small.

I agree. But it does perhaps double the surface area of the whole fuel tube apparatus. Maybe it reduces ice formation on the outside of the fuel line????

>> The canister would do just fine imho. After all, upright stoves do work in 'warm' weather'.

Ahh, but in an upright canister, the thermal mass of the liquid fuel remaining in the canister buffers the cooling effect. In a liquid-feed setup, the cooling would be dramatic in the fuel line until the temperature became too low for the fuel to completely vaporize upstream of the pre-heat tube. Also, in an upright setup, the canister itself can absorb heat from the environment, while the Xtreme canister is insulated by the black platic thingies from the fuel line (and preheat tube) where the evaporation takes place.

>> But the whole fuel line and burner have heat capacity, and would warm the fuel far better, and once the flame is there, who needs any other heat source?

We agree again. Hence, you can operate a conventional canister upside down. But, does it light easily and reliably? Can it simmer without sputtering out? The Coleman stove is designed for liquid feed and mass-market use. So perhaps it has these extra design details, that while not necessary for our Winter snow melting task, make it more user-friendly for the mass market.

BTW, Roger, as an engineer, I've really enjoyed your writings on bpl and your Aussi site. Thank you for your comments on this forum! Being able to have an exchange like this with someone of your credentials (or Ryan's for that matter) is one of the best things about BPL.

Edited by MikeMartin on 11/17/2005 21:39:57 MST.

Bill

I have taken over as Stoves Section Editor at BPL from Will R. My bio will appear one day on the masthead ...
In the meantime, I wonder if you would be willing to contact me direct? Probably a breach of whatever on this forum, but my address will be public soon anyhow. My email is (I think):
roger@backpackinglight.com

> > Good theory, but I suspect the amount of energy input via the mag block would be small.
> I agree. But it does perhaps double the surface area of the whole fuel tube apparatus. Maybe it reduces ice formation on the outside of the fuel line????
'reduces' is unlikely: the whole lot would be way sub-freezing anyhow in mid-winter.

> while the Xtreme canister is insulated from the fuel line (and preheat tube) where the evaporation takes place.
If evaporation IS taking place in the fuel line, the ambient must be pretty warm. Butane boils at -0.5 C (31 F), while propane boils at -40 C (-40 F). It is quite possible that the propane boils off somewhere in that black tube Bill showed us and bubbles up to the jet at the start. But if it does, this leaves butane behind, and that is likely to be liquid, and so will reach the jet in liquid state.

> Hence, you can operate a conventional canister upside down. But, does it light easily and reliably? Can it simmer without sputtering out?
Experiment trumps theory every day. I stuck a Snow Peak GS200D in the freezer for a while, then took it out and lit it immediately with the piezo. Absolute delight to operate, as easy as the Xtreme. (So far, so good.)

You will be getting me as the Stoves Section Editor for a while on BPL. Sorry about that. :-)

Mr. Caffin,

Congrats on the editor position. BPL sure knows how to pick 'em. Good move BPL.

>>"Experiment trumps theory every day."

three points:
1) obviously, the experiment must be properly set up.
2) decades ago, pioneer aviator, inventor, engineer, Igor I. Sikorsky was fond of saying to young engineers: "When the facts disagree with the theory, I urge you young gentlemen, to accept the facts."
3) the "Rhiele Axiom", states, "One Test is worth a thousand expert opinions." Test Engineers the world over swear by this principle.

Edited by pj on 11/18/2005 02:48:27 MST.

> Mr. Caffin,
> Congrats on the editor position. BPL
> sure knows how to pick 'em.
Let's hope so!
But look guys - 'Roger' will do just fine. I get enough of 'Dr Caffin' when I am playing professional scientist, but not here, please!
Cheers
PS: yes, I do have a few special Features in mind for stoves on BPL. They will take a little while to be completed, but stay tuned.

Hi Bill-

I saw your milling machine post on the Winter SUL thread and thought it would be more appropriate to discuss a few things here.

1) First, let me say that I have no experience machining anything. But, I've read that Magnesium is hazardous to work with -- apparently the dust can ignite. I don't know how real the danger is or what your background is. But, I felt compelled to bring it up. Please be careful.

2) On a brighter note... If your new machine works well, could I hire you to skeletonize my casing for me? If you're interested, please email me at mmmei@aol.com. [thanks!]

Best Regards,

-Mike

Mike, This stuff isn't real Mag. I have worked with the real stuff and have a set of Real Mag wheels on a small very fast car I own. Talk about something being light.

Thanks for the warning about the Mag dust.

Anyway, as a potter I learned long ago to always wear a dust mask for what ever material I work with. I also have filed, scraped and a couple of things I don't want to admit to with very little success on this Mag?? alloy.

Let me see how this "casting" works out and then we can talk about yours.