The Evolution of a Winter Stove - Part 1
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Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Needle valve after pre-heat loop on 07/05/2013 16:48:19 MDT Print View

Hi Damien

> Having the needle valve after the pre-heat loop, is there any danger of excessive
> pressure building up in the fuel line due to the high volume of expansion that
> happens when the fuel vaporizes?

Nope. If the pressure in the line near the needle valve gets higher than the pressure in the canister, it will simply stop the fuel coming from the canister. Actually, that happens all the time in any remote canister stove: fuel oscillates back and forth.

If you take the fuel in the region of the needle valve and heat it to 1,000 C, you might think that could raise the pressure. Nope: it will still push back into the canister and recompress fuel vapour back into liquid.

On the other hand ... if you heat the canister to 100 C, you can expect instant transmogrification. See http://www.backpackinglight.com/cgi-bin/backpackinglight/exploding_gas_canisters_the_hazard_of_overheating.html

Cheers

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Re: CO on 07/05/2013 17:05:48 MDT Print View

Hi Nick

> MSR Pocket Rocket among the worst and Snow Peak GigaPower among the best.
Well, the PR was not good. The full data is at http://www.backpackinglight.com/cgi-bin/backpackinglight/stoves_tents_carbon_monoxide_pt_3.html but a few stoves extracted are:

Optimus Crux: 300/260 (low/high, ppm)
MSR Pocket Rocket: 240/140
Coleman Xtreme: 5/5
Snow Peak GST-100: 5/21
FMS-116T: 10-50/50-100 (The FMS stoves are from later testing)
FMS-300T: 20/3

The variable results with the FMS-116T are due to some solid Titanium in the flame: while that metal is 'cool' the CO emission is high, but it drops as the metal heats up. (No recirculation was harmed during the testing.)

As far as the Reactor goes - we tested a preproduction model and found >1,000 ppm emission at low power. Boosting the air inflow (with a compressed air line!) reduced the emissions enormously. We sent these results in to MSR and they withdrew the Reactor from the market weeks before its release as a result of our report.

Several months later MSR reissued the Reactor with modifications to improve the air flow. It still tested very high (350 ppm at low power), but obviously not as bad. We reported on this at http://www.backpackinglight.com/cgi-bin/backpackinglight/co_series_supplement_1_msr_reactor.html Yes, we still have all the correspondance with MSR over this.

If you only use a Reactor at full power the CO emissions are lower. It was not designed for low power or cooking, but may be useful outdoors for melting snow.

Cheers

Edited by rcaffin on 07/05/2013 17:11:36 MDT.

David Thomas
(DavidinKenai) - MLife

Locale: North Woods. Far North.
Re: Re: Enclosed areas. on 07/05/2013 18:49:57 MDT Print View

>"since I am not a scientist."

I'm not a scientist either. Scientists do things like entangle more photons than any human ever had before or find an exception to the Heisenberg Uncertainty Principle. Both of which my BIL has done. Engineers clean up toxic waste sites, build snowball cannons and backyard zip lines for their kids, and bring portable hot tubs on backpacking trips. All of which I've done.

Engineers (generally) don't publish in Science or Nature.

Scientists (generally) don't use pipe wrenches and voltmeters. Nor are they satisfied with one significant figure.

Scientists discover things no one ever knew before. Engineers get paid better.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Re: Enclosed areas. on 07/05/2013 21:40:19 MDT Print View

> Scientists discover things no one ever knew before. Engineers get paid better.
Sulk.
Snark.

Sigh
PS: I own about 6+ voltmeters...

Edited by rcaffin on 07/06/2013 16:40:58 MDT.

peter vacco
(fluff@inreach.com) - M

Locale: no. california
Re: Re: Re: Re: Enclosed areas. on 07/06/2013 18:35:03 MDT Print View

" I go for experimental results over theory every time. "
yes. quite correct. i have read that the laws of thermodynamics owe more to James Watt's engine, than his engine will ever owe to the laws of thermodynamics. (it was a horrible thing efficiency wise).
also somewhere along those lines, is, "if it looks good on paper, but doesn't work in real life .. you've got it written down wrong."
---
anybody hanker'n to produce something in quantity might be well advised to read/study/come-to-Believe, Rajan Suri's principles of Quick Response Manufacturing.
they are a godsend of common sense, that is a good leap forward from what is openly obvious.
(and to boot, you'll make a better product with less scrap)
---
if ever the little voice in your head shuts off, and you are still alive, there is a fine chance you have CO poisoned yourself.
(tuck that tidbit of information away. you may need it someday.)
---
great article. we can all see how as a product evolves, several generations of equipment may be purchased and quickly discarded as knowledge matures during a manic development cycle.
---
peter gives not a squat of snot about CO coming off a pot.

David Thomas
(DavidinKenai) - MLife

Locale: North Woods. Far North.
Wallet-limiting career choices. on 07/06/2013 18:53:47 MDT Print View

> Sulk.
> Snark.

In my major, we'd say, "Chemical Engineers just want to be chemists. Chemists just want to be physicists. Physicists just want to be mathematicians. Mathematicians just want to be philosophers. Philosophers just want to be God. Unfortunately (for the rest of them), the pay scale is the other way around."

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Wallet-limiting career choices. on 07/06/2013 21:12:40 MDT Print View

Hi David

Where'd you put the programmers?

Cheers

Jason Brinkman
(jbrinkmanboi) - MLife

Locale: Idaho
What's that got to do with...? on 07/07/2013 02:11:30 MDT Print View

What do programmers have to do with the price of tea in China?! :)

For that matter, what do exhaust recirculation patterns, carbon monoxide pools, snow caves, or faulty lanterns have to do with Roger's new stove?

If someone were to try hard enough, they could probably off themselves with their titanium spork, but the prudent user has predictably few problems. I'll give you that canister stoves (or mis-assembled lanterns) are slightly more risky than sporks, but with rare (albeit notable) exception, the average user survives more times that not.

Oh, and I am definitely intrigued by the cliffhanger, Roger... Let's see that baby!

Edited by jbrinkmanboi on 07/07/2013 02:36:28 MDT.

Jason Brinkman
(jbrinkmanboi) - MLife

Locale: Idaho
Manufacturing on 07/07/2013 02:13:53 MDT Print View

BTW, I've learned more than a couple things about prototyping and manufacturing from the responses here - good stuff! I like the notion of molded-in threaded inserts the most!

David Thomas
(DavidinKenai) - MLife

Locale: North Woods. Far North.
Re: Re: Wallet-limiting career choices. on 07/07/2013 08:25:09 MDT Print View

>"Where'd you put the programmers?"

Roger: that's what the physicists and mathematicians end up doing to pay the rent, IME.

Stuart R
(Scunnered) - F

Locale: Scotland
Re: Re: Re: Wallet-limiting career choices. on 07/07/2013 14:03:23 MDT Print View

Too true!

Then: BSc Applied Physics and Semiconductor Electronics

Now: writing code for things like the Dodge Viper engine management

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Manufacturing on 07/07/2013 16:14:11 MDT Print View

Hi Jason

> the notion of molded-in threaded inserts
You can also mold a plain hole and later press in a small brass or steel thread-insert. This usually lasts longer than self-tapping.

Cheers

Tad Englund
(bestbuilder) - F - MLife

Locale: Pacific Northwest
Re: Manufacturing on 07/08/2013 17:29:44 MDT Print View

Jason, I thought you fell off the end of the earth- good to see you are still alive.