Companion forum thread to:

The Myth of Pressure Regulators

Good article Roger

I've always been bugged by the claims of pressure regulators being better - I have to watch it carefully regardless, so if I need manually adjust it, no big deal.

I'm looking forward to part 2 - are there a few degrees below freezing where the pressure regulator works but the needle valve doesn't? and why?

Roger, good article, I always enjoy the facts of physics.

But if we always stayed with true facts, there would be a bunch of marketing people out of work; companies would have to come up with new, real, factually proven innovations to sell their stuff and the only people who would benefit is the consumer and that would be braking all the rules. So maybe we should stick with hype instead of physics, we don't want to mess the whole system up.

Hi Jerry

> are there a few degrees below freezing where the pressure regulator works but the
> needle valve doesn't?
A pressure regulator IS a needle valve.
So the answer is no. (in my humble opinion...)

Cheers
Roger Caffin (PhD, Physics)

Roger, Good Article!

Yes, a needle falve is a simpler form of a presure regulater.
Yes, some regulater stoves work at lower temps than others, given the same conditions... soo, it is not ALL hype and marketing spin.

These facts can have a hard time reconciling each other and seem to defy physics. Not true. Part of physics is how things work. I think I can guess how.

I agree 100% that other aspects and features of the regulator design are responsible. At a guess, I would postulate the following: A regulated stove will have some sort of mechanism to maintain a constant pressure at the outfeed side. This has the effect of somewhat warming the gases if heat from the flame is allowed to trickle back...be it iso-butane, n-butane, or propane. The trickle back heat from combustion will heat the regulater slightly, increasing gas pressure and causing it to feed back into the canister, soo, it is possible to use a regulator stove at lower temps or near empty canisters without violating any laws of physics. It just acts like a heat exchanger. The actual flame may sputter or run up and down slightly before it warms up, though. A phenomenon I observed in the first set of "comparison" videos released by SOTO a few years back. I may be all wet, of course.

Looking forward to part 2!

But what's funny is the stove marketers talk about the regulation effect - it will maintain a flow rate without you having to adjust it, which is a use less feature.

They don't mention working at a little colder temperatures.

Jerry, the SOTO does (my example.)

After all, his quote is just about perfect for this article (just swap pr for marketing).

"For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled."

Roger,

Excellent article and a really nice, thorough treatment of the subject. The diagrams are particularly helpful. In all, very nicely done, well except where you introduce information from that Hikin' Jim fellow. Sounds like a dodgey character to me. ;)

I look forward to part two,

HJ
Adventures in Stoving

"For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled."

I'm a big fan of Feynman's words on that sort of topic .... however ...

They don't apply here. The mass market outdoor gear industry (the supply side) operates under a different definition of success than Feynman. Their success is defined as enticing folks to buy the latest new thing ... repeatedly. Feynman's definition has a much longer horizon.

Also, for what it's worth, I'll submit that we (the demand side) are very often willing participants in that ... or want to be. Case in point, that hot new fabric treatment that repels water so well (I forget the name). How many threads have been started here lamenting that it hasn't made it to the market yet? Another case in point, there's a pack company that has discontinued a quite popular pack. I spoke with the owner about that and said I hoped they didn't drop another model that is a favorite pack of mine. His response ... Outdoor products have a life cycle independent of how great they are. Demand declines when they get to the point of being perceived as "old design". You have to refresh the product line once in a while if you are gonna stay in business. That perception of his is based on data. We (the market) are what drove that data.

It's nice to have folks like Roger around who are willing to put in the effort to deflate the hype surrounding the next best thing.

Edited by jcolten on 06/06/2012 16:22:04 MDT.

Very nice article, not that I'm a savvy enough technician to appreciate it all.

One bit of confusion - your first illustrations have the canister and P1 on the left, then you suddenly switch (canister and) P1 to the right. Huh?

It only took a minute or two to figure out what you had done, and probably most folks here being young and techie, understand such drawings better than I do.

But would it that hard to keep the gas flow going in the same direction in all the drawings?

Hi Jim

> Demand declines when they get to the point of being perceived as "old design". You
> have to refresh the product line once in a while if you are gonna stay in business.

This explains how the Volkswagon Beetle became the longest selling car in the world and one of the all-time greats.

This explains why some Au/NZ outdoors gear manufacturers are still producing AND selling the same design packs and tents some 30 years later - successfully.

This explains why Scarpa are still selling the same design leather boots 20-30 years later.

This explains why the the Australian Dunlop Volley and KT-26 shoe designs haven't changed in 30+ years, and still sell in really huge volumes.

I think the whole 'old design' idea is a marketing myth largely confined to the USA. American consumers have been conditioned to think this way, solely in order to keep the wheels of commerce spinning. It's how American industry keeps the consumer handing over his wallet, year after year. Brain washing.

Cheers

I looks to me like the manufactures are trying to use the pressure regulator to control the velocity of the gas over a wide temperature range through the jets. I think you are spot on in your disscussion of pressure. But I think velocity is the goal here. Thumb on the garden hose. I am getting old though, could be thinking wrong.

Roger, at least at first blush, seems to be a divergence between your view of benefits clamed for pressure regulators, especially considering your statement as follows:

"Claims for any significant performance improvements or differences in fuel consumption due to the use of a pressure regulator valve rather than a needle valve are total crap and hogwash, or extreme marketing spin. Or worse."

compared with Will Rietvelds's review last fall of the Jetboil Sol, describing its "thermo-regulate" technology as a benefit worth noting:

"Besides being lightened throughout, they incorporate the new Jetboil Thermo-Regulate™ Technology, which is a pressure regulator that maintains burner output as the fuel in the canister diminishes and improves performance in temperatures down to 20 F (-6 C)."

Excerpt from http://www.backpackinglight.com/cgi-bin/backpackinglight/sotm11_jetboil_sol_advanced_review.html

Maybe just a matter of degree of "improved performance" and defining what amounts to a "significant" improvement?

Or maybe the pressure regulator technology that you're analyzing is not the same technology used in the Jetboil?

I'm not an expert, or even an informed "pressure regulator" person, but it just seemed like there was a huge difference between what Will concluded (it's a benefit) and what you find (it's "total crap and hogwash").

PS -- I very much appreciate your tech articles, especially with all the extremely helpful pictures, charts, and diagrams.

PPS -- To drift a bit, why is it (as you've said elsewhere) that the Gnat has good CO levels when there's evidently a narrow space between the burner and the bottom of a pot resting on the pot supports? Thought that distance between pot bottoms and burners was a big factor for CO levels, with a lesser distance causing an increased CO level. And to make this "drift" semi-relevant, does a pressure regulator have any effect on CO levels, up or down?

Edited by JRScruggs on 06/06/2012 17:25:21 MDT.

Richard,

You've asked the proverbial $64,000.00 question. Why does the new Jetboil Sol have better cold weather performance? Hopefully Roger will address this in detail in part 2, but I think the main point of part 1 is that it is not due to the regulator, at least not directly.

HJ
Adventures In Stoving

Hi Richard

> the new Jetboil Thermo-Regulate™ Technology, which is a pressure regulator that
> maintains burner output as the fuel in the canister diminishes and improves
> performance in temperatures down to 20 F (-6 C)."

I don't mind the 'maintains output' bit, although I can't imagine ever running a stove for the time needed to notice this. The 'down to 20 F' bit is however pure marketing spin. The regulator needle valve has no effect on this. I suspect Will was just quoting the marketing spiel.

> why is it (as you've said elsewhere) that the Gnat has good CO levels when there's
> evidently a narrow space between the burner and the bottom of a pot resting on the
> pot supports?
Narrow space - true. However, my measured result is that the CO level is low.
The design of the burner is such that a LOT of air gets entrained, and the flame spreads sideways a fair bit (unlike, say, the Pocket Rocket). The flame height is very low and intense. The combination works.

> does a pressure regulator have any effect on CO levels, up or down?
No.

Cheers

I THINK I know what is going on to create differences between stoves, but I want to do some controlled experiments and get some solid data before I publish.

In fact, I had a preliminary part 2 written but it was not fit for publication, and it was not even totally correct. I withdrew it: just not good enough.

Part 2 will happen, but it will be a little while as the pile of work in front of me grows ...

Cheers

Hi Roger,

re: VW Beetle ... I owned (and thoroughly enjoyed) a pair of them and am sometimes tempted to buy an early 1960's vintage beetle to restore. However, in my heart of hearts I'd probably opt for a Karmann Ghia. But that's a cult thing and cults know nothing about "conventional wisdom".

You may very well be correct about "the next best (newest) thing" being a USA phenomenon ... I haven't traveled enough internationally to know first hand.

Roger --

Thanks for clarifying that there's no real dispute since Will was just "shilling" (unwittingly, no doubt) about benefits of the Sol's regulator.

As for the Gnat's good CO levels, I wonder why the Optimus/Brunton Crux/Flex do so poorly with CO levels considering that they, like the Gnat, have wide burners that would seem to cause flames to spread sideways (I don't have these stoves, so I'm going by photos that I've seen, together with my imagination). After all, that "wide burner w/spreading flames" feature is what helps make the Gnat's CO level better, as you explain below:

"The design of the burner is such that a LOT of air gets entrained, and the flame spreads sideways a fair bit (unlike, say, the Pocket Rocket). The flame height is very low and intense. The combination works."

Best wishes for Part 2 -- and good luck, too, since it sounds like Jim is promising you a $64K payoff if you answer the question about why the Sol does well in cold.

And Jim -- that's awfully nice of you!!! Better get your checkbook ready, though, since Roger probably already knows the answer.

Edited by JRScruggs on 06/06/2012 23:47:04 MDT.

MANY THANKS FOR THE EXPLANATIONS.

We have used the basic SOTO extensively for about 1 year. We did not appreciate that it was a pressure regulator but had noticed that the spindle moved in different directions for open/close than for our needle valve stove.

In general the SOTO stove has been fine for us under a great variety of conditions.

However on a few occasions, we found that on complete hard close a tiny flame remained & this was a real worry. We than found that if we opened the valve a smidgeon the flame then went out without further gas leakage. This problem has not reoccurred & we have assumed it was a transient problem with a small amount of debris or some such. We did not take the matter further.

Has anybody else had similar experience.

Lou D