Jim: I'll ask the propane guy next time I'm in town, but maybe you know:

Are there retail-level, liquid-feed propane tanks? Like 20-, 40- or 100-pound sizes?

I've assumed that the new OPD over-fill protection devices preclude inverting the modern 20-pound cylinders, but I suppose I should try that first.

But it's 15F, gusting to 30 mph and a bull moose (with one antler, a left-winger perhaps?) just bedded down next the garage. Maybe this afternoon!

Poor Alan, we've hijacked your preheat tube thread haven't we?

Good diagram. The question I have is: How hard is it to run a tube up the column (from a manufacturing standpoint)? Looks tricky to me.

I also have a concern that having the preheat tube inside the mixing chamber will change the dynamics inside the chamber. I can't say how, but I doubt it would be good.

I don't see the utility outweighing greater manufacturing costs and the necessity of redesigning the mixing chamber. Just one layman's opinion.

HJ
Adventures In Stoving

When I get any fuel canister, I weigh it and write the full weight on the bottom. Then when I use it all up, I weigh and record again ON THE CANISTER itself. Then I can check partials for how much fuel they have remaining. And, coincidentially, if someone were inclined to do a little refilling. . .

Jim:

In your article on the BernzOMatic propane can, you point out that upside down feeding liquid propane, a preheat tube might be needed. Have you tried using an inverted BernzOMatic propane canister with a stove like the MSR Windpro that already has a preheat tube?

Thank you for your inquiry. Unfortunately, the Powercell / Ultra Blue (8oz) line was discontinued in 2009.

There are no direct replacements or fuel cylinders.

We apologize for the inconvenience & appreciate your feedback.



Warm regards,



Armando G. Castillo

INSIDE SALES

WORTHINGTON CYLINDERS

A DIVISION OF WORTHINGTON INDUSTRIES

(P) 800.654.9011

(F) 614.840.4943

(D) 614.840.4928

Armando.Castillo@Worthingtonindustries.com

Hi Jim

> having the preheat tube inside the mixing chamber will change the dynamics inside the chamber.
That one I can answer. Yes, very likely. That mixing chamber looks so simple ... It AIN'T!

I did succeed in making and testing a mixing chamber that actually gave a better flame and lower CO when I *blocked off* two of the four air inlet holes. I was a shade startled at first.

Cheers

Mark Rash wrote: > In your article on the BernzOMatic propane can, you point out that upside down feeding liquid propane, a preheat tube might be needed. Have you tried using an inverted BernzOMatic propane canister with a stove like the MSR Windpro that already has a preheat tube?

Ken Larson wrote: > Thank you for your inquiry. Unfortunately, the Powercell / Ultra Blue (8oz) line was discontinued in 2009.

David Thomas wrote: > Jim: I'll ask the propane guy next time I'm in town, but maybe you know:

Are there retail-level, liquid-feed propane tanks? Like 20-, 40- or 100-pound sizes?

Stuart Robb wrote: > There is a degree of confusion here. As you were using the Brunton stand, you have a flow control valve at the canister end of the fuel line as well as the one in the stove itself.
You mentioned after my post that you were operating the valve at the stove, whereas I was assuming that you were using the valve at the canister to limit the flow/pressure to at least some degree. Was the valve at the canister just partially or fully open?

Recall my photos from earlier in this thread. Liquid feed 100% propane, GS-100 stove, no flaring.


Liquid feed, some mix of propane and isobtane (starting mix was 85/15, but canister was 2/3 empty), MicroRocket stove, flaring.


There has been some discussion as to why there was flaring with the one but not the other.

I went out for a brief hike this afternoon. I took along 100% propane again, but this time I took along a Markill HotRod stove (looks very much like a Kovea SupaLite or SnowPeak LiteMax). No flaring.


Guys, it's the fuel. The 100% propane has such a low boiling point that it vaporizes at the drop of a hat. Recall also that the surface area to mass matters. A small tube like the fuel line that connects one end of a Brunton Stove stand to the other has quite a bit of surface area compared to the amount of fuel flowing down the line. Given the length of the line, there's plenty of time for liquid propane to warm up enough to vaporize. Today, it was nice weather here. Probably 50F/10C when I was testing, maybe slightly warmer. All the heat in the world if you're propane and are willing to boil below -40 on either scale.

I did feel the canister, the fuel line, and the adapter I was using. The fuel line and adapter were quite cold. The canister was cold, but not as cold as I would have expected had vapor feed been occurring. The canister by the way was propped up by rocks. I am certain that liquid feed was occurring.

Again, I believe the lack of flaring is due to the use of 100% propane in relatively warm weather. In colder weather, I believe heat would have to be conducted from the burner to the fuel for proper vaporization. How cold would that be with 100% propane? I'm not sure. Perhaps Stuart, David, or Roger would have an insight here.

HJ
Adventures In Stoving

Edited by hikin_jim on 01/11/2012 01:50:22 MST.

David: Are there retail-level, liquid-feed propane tanks? Like 20-, 40- or 100-pound sizes?

Jim: I honestly don't know. I don't think even I could fit one of those in my backpack, so I haven't investigated them.

My interest is in refilling with 100% propane at home, not BPing with large canisters. :-)

Jim

You have perhaps forgotten one important point: the _only_ reason to run a stove with an inverted canister is to prevent the propane part of the normal propane/butane fuel mixture from being used up more quickly than the butane part. Well ok, it also avoids evaporative cooling of the canister contents, but that is a relatively minor issue and easily overcome.

So, when you have a canister of 100% propane, there is absolutely no need to have the canister inverted - there is no mixture and no component to use up faster. Evaporative cooling is a non-issue with a BP of -42C.
Use the canister upright and it should work perfectly with no chance of a flare up.

BTW, what kind of adapter did you get for the canister?

>"the (fuels) expand greatly (over 200X as I recall)"

I love the number 231. I teach it to junior engineers. Because:

231 cubic inches is a gallon

2.31 feet of water column equals one psi

231 mph was the world record wind speed at ground level set on Mount Washington in 1934.

Now I have another reason.

Fuel gases expand about 231 times from liquid to vapor.

Specifically, using vapor densities from Perry's Chemical Engineering Handbook and liquid densities from Roger Caffin's site on fuel efficiency:

iso-butane expands 225 times
n-butane 233 times
propane 266 times

They are slightly different because the size of the molecule doesn't effect its volume as a gas - only the number of molecule does. But the larger molecules do take up more space in a liquid. Expansion ratios are based on atmospheric pressure and standard temperature. Typically our fuels are colder than that which will increase liquid density a bit and increase gas density somewhat more.

Hi Stuart

> when you have a canister of 100% propane, there is absolutely no need to have the
> canister inverted - there is no mixture and no component to use up faster.
> Evaporative cooling is a non-issue with a BP of -42C.
Of course, if you are sitting at -40 C it might be worth while using liquid feed (ie canister inverted) to prevent the canister from cooling down! Allowing a bit of radiant heat to hit the canister could also be 'useful'.

My understanding is that there are places, like Finland, where one has to cater for -40 C. Hum ... a bit cool.

Cheers

>"there are places, like Finland, where one has to cater for -40 C"

And like my house. We've had -41C. But I wasn't camping.

I do notice the propane-fired grill doesn't get as hot at -20F (-29C). Certainly there are more losses off the sides and top. But I think I've also got a lower flame, although it could be a fuel/air ratio issue as well. Anyway, I've learned that below -20/-29, it's just easier and mroe comfortable to cook dinner inside.

Fairbanks usually sees -40 each winter. And -50F sometimes. That's just crazy, stupid cold.

I know people who've been camping in -40 and a very few who had -50F during an Iditarod dog mushing race. Except at that point, it wasn't a race, it was about survival.

And Roger, I know you're not too keen on alcohol stoves, but they use bigger versions to melt ice for the dogs. I'll be asking to see their rigs.

HJ said:
"Poor Alan..."
That's OK. I wonder if the little 170 cans could hold propane and meet regs, but maybe more conventionally thick walls: probably no market anyway.

HJ said
" How hard is it to run a tube up the column (from a manufacturing standpoint)? Looks tricky to me"
" also have a concern that having the preheat tube inside the mixing chamber will change the dynamics inside the chamber. "

Roger Caffin said
"That one I can answer. Yes, very likely. That mixing chamber looks so simple ... It AIN'T!"


A simpler alternative would to be to just run the preheat tubes close to the outside of the conventional burner column, so that they are tucked in, and braced against it, rather than more exposed to knocks out on their own.

That cheap $16 remote stove (with tubing of unknown quality) seemed to use the pot stand to protect the tubes, which seemed neat. Some branded remote stoves seem to have more preheat tubing that would seem necessary (e.g. the primus spider): surely that's just extra weight?

Hi Roger

"Of course, if you are sitting at -40 C it might be worth while using liquid feed (ie canister inverted) to prevent the canister from cooling down! Allowing a bit of radiant heat to hit the canister could also be 'useful'."

As I alluded to, there are other ways to overcome this, such as convective heating :-0

But I admit it: I am soft, I don't go camping when it's -40C

Stuart Robb wrote: > You have perhaps forgotten one important point: the _only_ reason to run a stove with an inverted canister is to prevent the propane part of the normal propane/butane fuel mixture from being used up more quickly than the butane part. Well ok, it also avoids evaporative cooling of the canister contents, but that is a relatively minor issue and easily overcome.

Stuart Robb wrote: > BTW, what kind of adapter did you get for the canister?

Edited by hikin_jim on 01/11/2012 11:38:10 MST.

Fuel gases expand about 231 times from liquid to vapor.