Stoves, Tents and Carbon Monoxide – Deadly or Not? Part 3: Laboratory Measurements for Canister Stoves

[Benjamin Smith]

Companion forum thread to:

Stoves, Tents and Carbon Monoxide – Deadly or Not?
Part 3: Laboratory Measurements for Canister Stoves

[Roger Caffin]

Hi Tom

> on the underside of the Gravity burner there is circle of covered holes. The coverage of these holes is adjustable. Doesn't this influence the air supply to the jet?
Yes, it does, but during my testing I made sure the flaps were quite open. I didn't try the stove with them closed up – that was obviously not a good idea.

Cheers

[Woubeir (from Europe)]

Thanks Roger,
interesting remark about those flaps on the Gravity because they're closed when you buy the stove and nothing is mentioned about opening them in some sort of manual (unless I missed that part). I only decided to open them on my lst trip after rereading your article and noticing the air supply problem of this stove.

About the pressure regulator, if I understand it correctly the diaphragm limits the flow through the hole and the lower the flow, the lower the pressure, right? So the argument that such a system is very usefull in cold temperatures or with nearly empty canisters doesn't make sense. It looks more that gasflow out of full canisters is restricted than that gasflow out of nearly empty canisters is improved. Or am I misinterpreting what you're saying?
Or could there be another way for a pressure regulator to function so that flow at is improved instead of restricted?
Because otherwise I can't even understand why MSR mentioned the pressure regulator in its pressrelease or even thought of including such a regulator. It doesn't seem to have any real purpose.
Reason why I ask this is that Campingaz also has a stove with a pressure regulator, the Twister HPZ, and a couple years ago I had the opportunity to test one next to several other stoves. Because of the pressure regulator, with all the marjeting blabla, we decided to test the effectivity in cold temperatures, and the result was nill, nothing, zero, … That's not just marketing blabla, that's a pure lie. I can't understand why MSR would go the same way.

[Roger Caffin]

Hi Tom

> the diaphragm limits the flow through the hole and the lower the flow, the lower the pressure, right?
Well, it would be more correct to say the pressure controls the flow.

> So the argument that such a system is very usefull in cold temperatures or with nearly empty canisters doesn't make sense.
Well, if you design the system to work with a very low pressure to start with, then the pressure reduction at the regulator does make sense. This is why the large Propane (LPG) tanks always have a pressure regulator on the bottle. You would NOT want to put full pressure from a propane tank onto a stove.
This does not answer the question of whether the Reactor needs a regulator. I would not have thought so myself, but if MSR have gone to the expense of including one then I have to assume it is needed. No company includes features at extra cost if they are not needed.

Note: the release of the MSR Reactor was obviously delayed by our CO testing results. MSR claim to have fixed the CO problem, and have promised me a replacement stove for testing. It will be interesting.

The Twister is an upright stove, and if you were testing it in serious cold, yeah, it could well fail. It is not meant for cold weather.

Comment, entirely biased and ill-informed. If you want a heat-exchanger stove for cold weather and with low CO emission, then try the Primus EtaPower stove.
The Jetboil is heavy and dies in the cold (or the cool).
I have yet to test the modified Reactor.

Cheers

[Woubeir (from Europe)]

Hi Roger,
(un)fortunately, my Gravity stoves works perfectly (well, what you call perfect of course) so I don't need a new one. Although I am thinking of buying one of those etapower pots for efficient gastronomic cooking.

Sorry that I have to keep on asking things but a pressure regulator in stoves has intruiged me for a number of years now. Particularly since nobody seemed to use one except that French manufacturer in a not so particularly exciting stove. I've used the normal Twister for quite some years (because it was cheap) and the advanced model with pressure regulator didn't perform any better while costing twice as much. It's not that it can fail in cold weather that bothers me, it's the fact that Campingaz suggests that the pressure regulator is there to give better performance in cold weather that irritates me. And now MSR has come up with a pressure regulator and I'm wondering how usefull it is.

OK, pressure regulators can be usefull if you would want to work with a lower pressure like with propane and the regulator limits the pressure from canister to stove. And perhaps the internal mechanics of the Reactor stove need that lower pressure. But what I still don't understand is how a pressure regulator can help when the pressure in a canister is already low (because it's empty or because it is cold). Do claims that a pressure regulator helps a simple butane stove perform better in winter than that same stove without regulator, make any sense?

Sorry that I keep on asking but my engineering degree forces me to question as much as I can. :-)

[Roger Caffin]

Hi Tom

> But what I still don't understand is how a pressure regulator can help when the pressure in a canister is already low (because it's empty or because it is cold). Do claims that a pressure regulator helps a simple butane stove perform better in winter than that same stove without regulator, make any sense?
Yeah, your puzzlement is understood!
My own, unverified opinion, is as follows. It applies to both Campingaz and MSR if necessary.
Engineering found that they had to put the pressure regulator in to prevent problems (flare, blow-out) when someone turned the valve wide open, especially in HOT weather. They probably also found (or knew) that in cold weather the regulator was either ineffective or obstructive.
Marketing decided to make a big thing of it without fully understanding what they had been told, and came up with the ridiculous idea that the regulator would help in the cold. It won't.

I discount most of what I read in marketing releases and advertising. It eliminates a lot of confusion. (Like a bottle of distilled water with a 'New, Improved' label…)

Cheers

[Woubeir (from Europe)]

Roger,
your own unverified opinion is al I need to know. You just confirmed what I have been thinking for a long time but couldn't really explain. Unfortunately not everyone has the background to understand that some marketing statements don't make any sense.

BTW, how was your trip through "la douce France"?

[Roger Caffin]

Hi Tom

> some marketing statements don't make any sense.
It would not be the first time I have made unkind comments about 'marketing'…

France – wetter than expected, even snow in some places (in summer?) and exhausting … But we enjoyed it. We'll do it again, sometime.

[Robert Mohid]

Not having looked at the origial version Roger used for his CO testing. It looks like MSR's reduction stragegy was to plaster every square inch of the product with warning labels about carbon monoxide poisoning.

Roger, can you confirm that the version on the shelves now does indeed differ from the one you used for testing ?

[Robert Mohid]

If you're bound by an NDA from MSR, just don't reply Roger :)

[Roger Caffin]

> Roger, can you confirm that the version on the shelves now does indeed differ from the one you used for testing ?

I can confirm that MSR have made SOME changes, although not as many as I would have liked. Yes, they seem to be relying on using many warning labels to avoid any legal hassles. They do specifically warn about the CO hazard while simmering. No, I have not signed any NDA.

I now have a replacement Reactor and it is in test. Publication WILL follow – we are just working out how to handle the 'update' aspect for the web site. Cataloging issues.

The performance is better than it was, but it still emits a fair bit of CO, especially at simmer. This is one stove I would NOT use inside a tent or a building.

Cheers
Roger

[Robert Mohid]

Thanks for the update Roger !

I was/am planning on using this stove extensively in Alaska, I'll be looking very closely at your results, my life might depend on it.

[Jason Livingston]

Roger:

Thanks for the excellent article and insight. I do have a few questions about MSR's Internal Regulator (I'm sure your getting sick of these)…

The way I understand it is that the Reactor (from conversations Ive had with MSR) is engineered to perform optimally (roughly 10,000 btu) at only 13 psi. According to MSR, most stoves need 65 psi to perform at this level (based on a full canister). It makes sense to me that the pressure regulator in the Reactor maintains 13 psi throughout the life of the canister. In other words, when the canister is pumping out 65 psi, the Reactor restricts the flow to only 13 psi where it's able to produce 10,000 btu. When the canister gets low and/or as it cools down the pressure regulator is less restricted but maintains 13 psi. This would mean that the claims MSR is making regarding the need for a pressure regulator does work when the canister gets cold and the fuel level drops, which result in the pressure going down.

As I mentioned before, other canister stoves require 65 psi to obtain 10,000 btu. Thus as the fuel level in the canister drops and as it gets colder then less btus result. I'm wondering if this sounds right and is it possible to obtain 10,000 btu from only 13 psi?

Any insight would be greatly appreciated!!!

Jason

[Woubeir (from Europe)]

Well, Jason,
where did you get this question from ?
;-)

[Woubeir (from Europe)]

Roger, just to bring the question of Jason (see e few posts earlier) under your intention because I'm also interested adn in the flood of posts, this thread dissapears easily.
I understand that you have received an updated Reactor stove. Perhaps you could try to do some testing to see whether this pressure regulator really works and what the limits are?

[Jason Livingston]

I'm headed to the OR Show this week and will ask the engineers at MSR what their point of views are. As I am very familiar with MSR (Cascade Designs), I don't doubt that the internal pressure regulator is there for a purpose and probably does what they say it does, as Roger alluded to in an earlier post. What I would like to get is how and is it a different technology than has been introduced previously in other stores.

I would also be interested in reading about any new changes (now that the Reactor is in full production) was made on the stove and if the CO levels have decreased on simmer. I know this takes time. I'll try to be patient:).

[Jason Livingston]

In response to my own question and after doing some research and talking to one of the MSR stove engineers at the OR Show, I found out some interesting information:

The Reactor is a marvel of engineering. All the ingredients need to be there in order for it to perform as advertised. In my research, I found that the metal foam is one of the most efficient radiant burner materials on the market. What it allows the stove to do is produce heat throughout the entire surface of the foam much more efficiently and at a higher temperature than with an open flame or by using any other material such as ceramic. Because of this revolutionary foam, the Reactor can produce 9,000 btu at 11 psi. Thus the internal pressure regulator is needed to maintain the amount of psi allowed for optimum cold weather performance. Pretty ingenious! The most amazing thing is that this is only one of the engineering challenges faced. The fact that it is 100% windproof (100% primary air) and by using radiant and convective heat, the thought put into this stove is impressive.

The metal foam also heats up almost instantaneously and cools almost as fast. Although not the lightest nor, as Roger has outlined, the best stove for reduced carbon monoxide output, it is one of the best stoves in serious weather conditions often found in the backcountry. After owning one for a few months and using it in some pretty bad conditions, I am convinced that it is one of the coolest (no pun intended) pieces of gear I own!

In the Wind Rivers near Island Lake in Titcomb Basin, I used the stove to boil water inside my tent for both my food and hot chocolate. The tent I was using was the Hilleburg Akto (small one-man tent) and only used the stove long enough to boil the water. I didn't feel any adverse effects such as headaches, nausea, etc. that often accompanies high CO levels.

[Roger Caffin]

> The Reactor is a marvel of engineering.
I do not dispute this. I understand the concept behind the 'reactor' – a form of fluidised bed combustion. I do dispute whether it is the 'right thing' for walkers.

> it is one of the best stoves in serious weather conditions often found in the backcountry
Sorry, but I strongly disagree.

For a start, it will fail in the snow. Well, actually, it's the canister which will fail once the ambient gets sub-freezing. Granted, if you use an iso-butane/propane mix you can push the canister down a bit below freezing, but the idea of relying on a stove whose canister can freeze up in the snow is, to my mind, foolish.

Secondly, 'in serious weather' you do not want to be cooking outside. Get real. But cooking inside your tent with this stove has to be one of the most hazardous occupations around. I can only hope you had a LOT of ventilation going on at the time.

And finally, there are far better stoves available for use in serious weather. Why run the risks?

And yes to all: there is a review of the revised production version of the Reactor in the near pipeline. The CO levels have been improved – but they are still dangerous imho.

Cheers
Roger Caffin

[Woubeir (from Europe)]

Roger,
is there an opportunity to discuss the press regulator thing in the upcoming review? What it is, how it works, is the pressure regulator in the Reactor different or does the overall construction of the Reactor influence the functioning of the regulator, what it means or doesn't mean for the use of the stove in cold temperatures?

And that taking into consideration what Jason already mentioned (normal stoves need 65 PSI, Reactor supposed to need only 13 PSI, the radiant bed which needs only 11 PSI, …) and how the pressure drops inside the canister from about 75 PSI when full down to ??? when almost empty.

A number of reviewers have mentioned the great capability of the Reactor to function when temperatures are below 0°C. I don't know the exact conditons but it seems in contrast to what you are saying.

[Joshua Mitchell]

Yeah, the low pressure requirement will allow the stove to function down to a much lower temp than standard canister stoves, as well as eke out more of the fuel. However, there's still a limit imposed by the mixture of fuel used.

[Jason Livingston]

>For a start, it will fail in the snow. Well, actually, it's the canister which will fail once the ambient gets sub-freezing. Granted, if you use an iso-butane/propane mix you can push the canister down a bit below freezing, but the idea of relying on a stove whose canister can freeze up in the snow is, to my mind, foolish.

Sorry, but I strongly disagree due to my own personal experience. I've had this thing down to 10°F (according to my Suburu Outback's temperature gauge) with 20 mph winds and still watched it (along with about 20 other people) boil a liter of water at 3min. 30 sec. This is far below freezing using a half-empty isobutane propane canister while it was in a pile of snow. I was in Rocky Mtn National Park at a snowshoe demo. I feel comfortable using it down to about 5°F.

I would agree in very severe weather (below 0°F) I would opt for a white gas/multi-fuel stove, but anything above that up to freezing, the Reactor is the only canister stove that I would feel ok using. I've been in some pretty bad weather on the Sawtooths in Idaho, Wind Rivers in Wyoming, Uintas in Utah, and other places where traditional canister stoves wouldn't work. The Reactor is a whole other story.

Have you had a chance to use it outside the lab (not trying to be cute, but want to know if you, in your tests, have used it in "real world conditions")?

[Jason Livingston]

According to MSR, the pressure regulator is no different that what you would find in a backyard barbecue, just smaller. The big difference is the new metal foam that allows the stove to reach 9000 btu with only 11-12 psi. This is the "magic" of the Reactor, again according to MSR. Without this special foam, the internal pressure regulator wouldn't do anything, kind of like the Gaz Twister (didn't do much for this stove). This is also why you don't see it in any other backpacking stove.

The special burner is the key that allows the Reactor to do what it does, that is to overcome the effects of the pressure canister due to cold and low volume. The other major benefit the Reactor brings to the table is that it uses primary air only thus making it completely windproof (the worst enemy to any backpacking stove). And the radiant/convective pot also increases it's efficiency although it does create more CO emissions as a result.

It sounds like to me, Roger, though I totally agree with his CO emissions findings, has based whether or not he approves of the Reactor totally on the basis that it puts out a large amount of CO at low volume. Though important and something we all need to know, this stove's benefits should be also considered. It appears to me that there is a large amount of bias in his remarks IMHO.

[Jason Livingston]

>Secondly, 'in serious weather' you do not want to be cooking outside. Get real. But cooking inside your tent with this stove has to be one of the most hazardous occupations around. I can only hope you had a LOT of ventilation going on at the time.

Again, I disagree here. There are other dangers involved with using your stove in a tent. If, for instance, I understand the concerns with the amount of CO emissions it puts out, then I will take the needed precautions (more ventilation, only use at full volume, etc). I think a bigger threat is burning down the tent when priming. I have, on several occasions, cooked my food in pouring rain, blizzards, etc. outside my tent. The fact that I need only about 3 minutes with the Reactor makes it doable.

Due to the massive rainstorm that hit me, I completely buttoned up my tent. As most people know, the Akto isn't the best ventilated tent around, but, again, I felt no adverse effects. I know how subtly carbon monoxide can effect a person and I was fully aware of this while using the stove (I'm always concerned about this no matter what stove I'm using). If I find I am getting headaches or feeling sleepy, I immediately turn off the stove. I felt no such thing (I was operating it at full volume for the quickest boil).

I do plan on making sure that I am very careful (more so now due to your report) with the Reactor while using it in my tent, but due to my experience, I plan on continuing to use it in a tent when necessary. I try not to use it there as much as humanly possible, but as you said, let's get real. There are times (very few times) when there is no other way.

[Jason Livingston]

Post Deleted.

[David Thomas]

“other dangers involved with using your stove in a tent. . .  I think a bigger threat is burning down the tent when priming.”

That’s certainly true with a white-gas Optimus or Svea stove if you weren’t carefully dialed-in and recently practiced starting it at the current ambient temperature.   But this article is about canister stoves which, in vapor-feed mode, need no priming.  And in liquid feed, it’s not hard to avoid any flare-up, correct?  Low vapor-feed flame until the vaporizer tube is at temp and then invert the canister.

Or just use a Moulder Strip and operate in vapor-feed at all times.  That works to far lower ambient temperatures (-25F) than inverted-feed does.

(I ended up here, 11 years later because of the recent release of #5 in the series and my following that back to #3).

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