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#226437 - 06/22/11 05:06 PM The Soto OD-1R Microregulator: Cold weather OK?
Hikin_Jim Offline
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Registered: 10/12/07
Posts: 1804
Loc: Southern California
There's been a lot of "buzz" about the Soto OD-1R microregulator (which is a lightweight, compact upright canister stove) being able to handle cold weather. A lot of that buzz has been generated by Soto's advertising showing such things as their stove blazing away when the fuel is submerged in ice water while "brand 'X'" fades out. The relevant section of the video starts at about 63 seconds in.



Has Soto licked the cold weather problem for a lightweight upright canister stove? How much better performance can one expect? I try to separate the facts from the fiction in my latest blog post: The Soto OD-1R Microregulator: Cold weather problems solved?

HJ
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#226459 - 06/22/11 09:35 PM Re: The Soto OD-1R Microregulator: Cold weather OK? [Re: Hikin_Jim]
Am_Fear_Liath_Mor Offline
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Registered: 08/03/07
Posts: 3078

Hmm, neat Soto trick with their microregulator valve in their video, assuming that both upright stoves are using the same cannister fuel types, it looks like the Soto has an incredible advantage, but what is probably happening here is that the Soto is just burning a much higher percentage of the propane, i.e. if Soto had kept the video running then the Soto stove would have went completely out around the 10-15 min mark whilst the other stove would have continued for over an hour or more.

All that was needed for the other non Soto stove to match the Soto stove was the valve to be opened up and it too would have conked out around the 10-15 minute mark as it burned off the propane content of the canister.

It would be interesting to compare real low temp performance between the Soto and say a Primus Express Spider and a Etapower pot for performance and efficiency. I think I could easily live with the addition 200 gms considering the advantages the Spider stove will give.





Edited by Am_Fear_Liath_Mor (06/22/11 09:45 PM)

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#226461 - 06/22/11 10:11 PM Re: The Soto OD-1R Microregulator: Cold weather OK? [Re: Am_Fear_Liath_Mor]
Hikin_Jim Offline
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Registered: 10/12/07
Posts: 1804
Loc: Southern California
It's hard to know exactly what's going on in that video, but it's not related to the amount or percentage of propane burned -- unless they used different fuel mixtures for the two different burners. Using different fuel mixes to try to make one's product look good would be pretty unethical.

Let's assume that the two tanks of gas have the same mix and amount of butane, isobutane, and propane and that the two valves are more or less equally open. Given these assumptions, there's a simple way to make the Soto Micro Regulator look good: Just use the right mixture of gases.

What do I mean? First, recall the vaporization points of the gasses used for backpacking stoves:
Code:
Boiling point
n-butane	-0.5C	31F
isobutane	-12C	11F
propane		-42C	-44F


Now, how cold is that ice bath? Considering that liquid water is present, it cannot be colder than 32F/0C. In fact, unless crushed ice is used, an ice water bath is probably warmer by a few degrees, but for simplicity's sake, let's call it 32F/0C.

OK, for a needle valved stove to work, the fuel temperature needs to be about 10F/5C above the vaporization point of the mix of fuels. For a regulator valved stove, only a 5F/2.5C difference is needed. When you mix gas fuels, the vaporization point of the mixture is determined by the molar fraction of the various component fuels. Molar fraction is a fancy way of saying percent of the total as measured by by the number of molecules (not mass and not volume). All Soto needs to do is come up with a mix that vaporizes around 37F/2.5C and their regulator valved burner will burn reasonably well while a needle valved burner will struggle. Soto's burner will look like a wonder of science and technology while a standard burner will look like a dog.

The reality is though that the Soto burner, while it does have an advantage, only has an advantage over a fairly narrow temperature range. As I say on my blog the fuel mix you buy is far more critical to cold weather performance than the type of valve on your stove. You can also employ various means to keep the fuel warm. Keeping the fuel warm will give you a much bigger performance boost than using a regulator valve will. And, as I say on my blog post, if you're thinking about going out in really cold weather (below 20F/-7C), don't bring an upright canister stove; switch to a remote canister stove with a preheating mechanism so that you can invert the canister and run your stove in liquid feed mode.

I believe the Primus Express Spider you mentioned is just such a remote canister stove, one with a preheat mechanism. As such, the Spider should be able to operate (with the canister upside down) in weather down to about 0F/-18C provided that you purchase a fuel that contains only isobutane and propane and does not contain "regular" butane.

HJ
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#226462 - 06/22/11 10:36 PM Re: The Soto OD-1R Microregulator: Cold weather OK? [Re: Hikin_Jim]
Am_Fear_Liath_Mor Offline
Carpal Tunnel

Registered: 08/03/07
Posts: 3078
Quote:
The reality is though that the Soto burner, while it does have an advantage, only has an advantage over a fairly narrow temperature range.


I can't see any advantage at all over any other gas cartridge stove using the same fuel mix cartridge with regard to usable temperature range. The only difference is that the area of the orifice which the fuel gases are seeing is larger for the Soto, which simply means that more of the fuel such as the propane and isobutane with their lower boiling points is being used. The rate of these gas vapours (propane and isobutane) are being consumed is much much greater as very little butane is being consumed due to the very small temperate difference of around 1C. i.e. very little butane is being vapourised. This can be seen in the video with the Soto's greater initial heat output.

All this means is that, at these temperatures around 0C the Soto will go out leaving around 60% of the fuel (mostly butane) left in the canister about 10-15 minutes into the burn.

In fact the Soto could lead folks into a false sense of security thinking they have an hours worth of fuel left at these cold temperatures when in fact they might just have 10-15 minutes burn time.

It might be more prudent to capture the lower heat output of the ordinary stove more efficiently with its much longer lower output i.e. use a heat exchanger pot such as the Etapower pots.

What the video needs to do is run the burn to the end, when both cartridges stop producing a flame, then weigh the cartridges to see which stove burned the most fuel. It probably wouldn't be the Soto.



Edited by Am_Fear_Liath_Mor (06/22/11 10:47 PM)

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#226478 - 06/23/11 06:19 AM Re: The Soto OD-1R Microregulator: Cold weather OK? [Re: Hikin_Jim]
MostlyHarmless Offline
Old Hand

Registered: 06/03/09
Posts: 982
Loc: Norway
Originally Posted By: Hikin_Jim

I believe the Primus Express Spider you mentioned is just such a remote canister stove, one with a preheat mechanism.


Yes, it is. I want one...

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#226479 - 06/23/11 06:20 AM Re: The Soto OD-1R Microregulator: Cold weather OK? [Re: Am_Fear_Liath_Mor]
MostlyHarmless Offline
Old Hand

Registered: 06/03/09
Posts: 982
Loc: Norway
Originally Posted By: Am_Fear_Liath_Mor

All this means is that, at these temperatures around 0C the Soto will go out leaving around 60% of the fuel (mostly butane) left in the canister about 10-15 minutes into the burn.

In fact the Soto could lead folks into a false sense of security thinking they have an hours worth of fuel left at these cold temperatures when in fact they might just have 10-15 minutes burn time.


This is my understanding as well. Which is why I'm such a big fan of inverted canisters (liquid feed operation) and a pre-heat loop.

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#226506 - 06/23/11 04:55 PM Re: The Soto OD-1R Microregulator: Cold weather OK? [Re: Am_Fear_Liath_Mor]
Hikin_Jim Offline
Sheriff
Pooh-Bah

Registered: 10/12/07
Posts: 1804
Loc: Southern California
Originally Posted By: Am_Fear_Liath_Mor
I can't see any advantage at all over any other gas cartridge stove using the same fuel mix cartridge with regard to usable temperature range.
The advantage of a regulator valve is that it will operate with lower canister pressure. The ability to operate with a lower canister pressure allows one to operate a stove like the Soto OD-1R at a slightly lower temperature (temperature being the chief determiner of gas pressure), about 5F/2.5C lower. Is this a material advantage? That's up to the individual to decide.

Originally Posted By: Am_Fear_Liath_Mor
The only difference is that the area of the orifice which the fuel gases are seeing is larger for the Soto...
Well, not exactly. The size of the orifice is not material. The ability of a regulator valve to operate at a lower pressure than a conventional needle valve is what allows the Soto to maintain a larger flame.

Originally Posted By: Am_Fear_Liath_Mor
...which simply means that more of the fuel such as the propane and isobutane with their lower boiling points is being used. The rate of these gas vapours (propane and isobutane) are being consumed is much much greater as very little butane is being consumed due to the very small temperate difference of around 1C. i.e. very little butane is being vapourised. This can be seen in the video with the Soto's greater initial heat output.

Let's talk for a moment about the physics of gas, in particular a blend of propane, isobutane, and butane, the gases typically used for backpacking type stoves. The myth is that "very little butane" will be vaporized and that basically only those gases with vaporization points well below the actual temperature of the fuel will vaporize. Not true, or at least not quite. When you blend fuels, they behave as a blend, not as individual fuels (remember, that's a liquid in your gas canister). In the case of a fuel canister containing propane, isobutane, and butane, you don't have three vaporization points, you have one. That one vaporization point is determined by the relative percentages of each of the fuel components as measured in numbers of molecules (i.e. the molar fraction). Now yes, the components with lower vaporization points do tend to vaporize faster, so your mix absolutely will change over the "life" of the canister. Indeed, towards the end of the canister, you will have just butane left. However, you will have burned off far more butane than you would if you had been trying to burn a canister of 100% butane all along. The reality of blended fuels is that poor cold weather fuels like butane burn better when combined with better cold weather fuels like isobutane and propane.

Originally Posted By: Am_Fear_Liath_Mor
What the video needs to do is run the burn to the end, when both cartridges stop producing a flame, then weigh the cartridges to see which stove burned the most fuel. It probably wouldn't be the Soto.
Actually, all else being equal, the Soto will absolutely burn more fuel. Remember that a regulator valved burner can operate at a lower pressure than a conventional needle valved burner. As the fuel canister empties, the pressure drops. Toward the end of a canister, there will be insufficient pressure to operate the needle valved burner, but the regulated burner will continue to function.

If you ran a head to head test at say 50F/10C between a regulator valved burner and a needle valved burner wherein you ran both burners until the gas* canisters of each were exhausted, the regulator valved burner would consistently be able to use more of the fuel in its canister. The needle valved burner would consistently leave more fuel unconsumed in its canister.

If you were to run the same test at 32F/0C, the difference will be in the Soto's favor more dramatically since the cold will further inhibit pressure, giving the Soto an even greater advantage.

HJ

*Assume a blend of 10% propane, 40% isobutane, and 50% butane.
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#226507 - 06/23/11 05:22 PM Re: The Soto OD-1R Microregulator: Cold weather OK? [Re: MostlyHarmless]
Hikin_Jim Offline
Sheriff
Pooh-Bah

Registered: 10/12/07
Posts: 1804
Loc: Southern California
Originally Posted By: MostlyHarmless
...I'm such a big fan of inverted canisters (liquid feed operation) and a pre-heat loop.
Remote canister stoves with a pre-heat mechanism are indeed game changers in terms of how gas stoves operate and how cold of a temperature you can operate the stove in.

With upright canister stoves, vapor is drawn off the top. The better cold weather gasses (propane and isobutane) vaporize at a faster rate. Your fuel blend changes over time, with decreasing performance as you near the end of the canister.

When you invert the canister, you're now drawing liquid off the bottom. Since you're not drawing vapor, the respective vaporization rates of the component fuels are simply not relevant. The liquid you draw off the bottom continues to be the same blend as what you started with. If you started off with a fuel blend with good cold weather performance characteristics, you'll finish with a fuel blend with good cold weather performance characteristics*. With a blend of 30% propane and 70% isobutane, a remote inverted canister gas stove will run fine at temperatures below 0F/-18C. Also, since you're doing liquid withdrawal, you're not going to have the same amount of evaporative cooling of the fuel. In other words, your inverted fuel canister won't get as cold as an upright canister -- further contributing to good cold weather performance.

Below 40F/5C, I generally recommend switching either to a remote inverted canister stove or a liquid fueled stove. Yes, you can run an upright canister stove at lower temperatures, but you're going to get a lot better performance out of a remote inverted canister or liquid fueled stove.

HJ

*In actual practice, some remote inverted canister stoves -- those that require the canister to be upright during startup -- will experience changes to the fuel blend over the life of the canister.
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#226509 - 06/23/11 06:13 PM Re: The Soto OD-1R Microregulator: Cold weather OK? [Re: Hikin_Jim]
Am_Fear_Liath_Mor Offline
Carpal Tunnel

Registered: 08/03/07
Posts: 3078
Quote:
The ability of a regulator valve to operate at a lower pressure than a conventional needle valve is what allows the Soto to maintain a larger flame.


This depends on the Stove, take for example the Coleman F1 power stove, it has a rated output of 7000W compared to the Soto around half that, which means the valve on the Coleman is allowing 2x the gas flow of the Soto. i.e. the orifice area of the needle valve in the Coleman is much larger. With all things being equal such as the same gas mixture and operating temperature, the Coleman will output more heat that the Soto over the entire temperature range. You just need to open the needle valve up on the Coleman to match or exceed the Soto. Of course the Coleman will run out of fuel more quickly than the Soto and the Coleman may even have a lower efficiency overall as efficiency drops away with ever higher outputs. i.e. it will bring less water to a boil over the lifetime of the cartridge.

Can you point me to any reliable evidence that the Soto regulation valve works with lower gas pressures past the Lindal valve compared to a needle valve which is regulated by the operator esp with stove with a higher rated BTU spec. I still cannot see how a regulated valve has any bearing to the temperature abilities of the stove. Its rather like saying this a amplifier/speaker setup is louder because it has 11 on the dial. wink

http://www.youtube.com/watch?v=XuzpsO4ErOQ





Edited by Am_Fear_Liath_Mor (06/23/11 06:28 PM)

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#226518 - 06/23/11 08:37 PM Re: The Soto OD-1R Microregulator: Cold weather OK? [Re: Am_Fear_Liath_Mor]
Hikin_Jim Offline
Sheriff
Pooh-Bah

Registered: 10/12/07
Posts: 1804
Loc: Southern California
Originally Posted By: Am_Fear_Liath_Mor
Quote:
The ability of a regulator valve to operate at a lower pressure than a conventional needle valve is what allows the Soto to maintain a larger flame.


Can you point me to any reliable evidence that the Soto regulation valve works with lower gas pressures past the Lindal valve compared to a needle valve which is regulated by the operator esp with stove with a higher rated BTU spec. I still cannot see how a regulated valve has any bearing to the temperature abilities of the stove.
Ah. I see where you're coming from. You don't accept the premise that a regulator valve will operate with lower pressure than a needle valve.

The only real way to prove that a regulator valve can operate at a lower pressure than a needle valve is with testing. One could:
a) Take two comparably rated stoves, one regulator valved, one needle valved, and run them with identical canisters at temperatures where the internal canister pressure will be reduced. With the valves 100% open, observe any difference in the flame between the two stoves.
b) Hook a manifold to a single gas source and run it through both stoves and observe how each valve type's flame responds at a given pressure. One would be allowed to adjust the valve settings at will during the test.

I have been intending to do a test of type "a" myself since I have all the necessary equipment. I just haven't had time.

However, a test of type "a" has already performed for us: Take a look at the video from Soto in my original post. Note how far they open the needle valve on the non-Soto stove. It's fully open. Next note that the flame sizes are equal at the start. Then note that while the flame diminishes on the conventional burner, that the lower pressure does not significantly affect the output of the Soto burner. Clearly, the regulator valved burner can run at a lower pressure than a conventional burner.

While the video does demonstrate the Soto's technological advantage, my criticism of the video is that Soto doesn't mention that the temperature range is very narrow (at which a regulator valved burner will outperform a needle valved burner -- only about 5 degrees Fahrenheit/2.5 degrees Celcius) in width.

Not only do we have a test of type "a" available to us, we also have a test of type "b" available:

Notice how far he opens the conventional burner on the left. It's wide open. Then watch as he reduces the pressure by lowering the temperature of the fuel. In the video he says "ambient" temperature which of course is incorrect. He's altering the temperature of the gas (not the ambient temperature) which reduces the gas pressure. Again, a clear advantage on the Soto's part at lower temperature/pressure is demonstrated.

Notice though the temperature markings (in Fahrenheit) on the gauge. He never takes the gas temperature below about 20F/-7C. He's playing to his stove's strengths, that narrow band at which his stove will outperform a conventional burner. So, while a regulator value does have an advantage, it's a modest one, spanning about a 5 degrees F/2.5 degrees C range. Had he dropped the temp to 0F/-18C, the Soto micro regulator would be as dead as a door nail, just like a conventional burner.

To my mind, the real advantage of a regulator valve is getting the most out of your canister of fuel. Here, I'm relying on my experience with another regulator valved stove, the MSR Reactor. When I burn through a canister with a Reactor, that canister is empty. When I use conventional needle valved stoves, there's always a bit of fuel left in the canister.

HJ
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