Fuel in "8oz" size Isobutane canisters

Two things you wrote, Jerry

“–propane is less useful because it boils off.” So then you give Hikin’ Jim a +1 for suggesting that having some propane in the canister is a good thing? So where do you actually stand, propane good or propane bad?

“–Maybe experiment running at full speed.” It could be done, but it would be silly for me to do that. I always set my flame throttle between medium-low and medium in the field, for fuel efficiency. So that’s what I want to do for this test, to mimic real world conditions. But if I wanted to do the test in the shortest possible time, running the throttle at full bore would probably be the way to go.

@Jim… My patio sits at 5440′ outside Boulder. My calculations indicate that iso-butane should vaporize at about +2.3* F at that altitude. I found a chart that says it vaporizes at +3* F at 5000′, and I interpolated it to be + 2.3* F for my elevation. If that’s true, I might not be able to reach the shutdown temperature, unless self-cooling of the canisters plays its A-game. It might drop below +10*F Tuesday night, but likely not. I will post my results once I’m done with the test, probably in this thread.

My main interest is to learn whether the Olicamp fuel indeed performs the same as Jetboil’s. I also want to report back to the buyer at my local sporting goods store. He chose to drop the Jetboil line of fuels in favor of the Olicamp brand, and I want to let him know how I think they compare.

This is all discussed, with graphs, at The Effect of Cold on Gas Canisters right here at BPL.

Cheers

Gary,

Just as a quick ballpark estimate (with apologies to Roger and Stewart and their far more precise calculations), ? you can deduct about two degrees Fahrenheit per 1000′ above sea level or about 1 degree Celsius per 300m from a given boiling point.

Sounds like you’ll be about maybe 10 degrees Fahrenheit above the boiling point of isobutane. I would think that you’d still see the effects of the temperature on canister pressure, particularly when you factor in canister cooling.  One thing you could do is to run the stoves continuously, not turning them off in between boils.  This would induce maximum canister cooling.  If one or the other maintained good pressure significantly longer, that would be the better brand — assuming that you were able to set the rate of burn the same on both.  To really do it right, you’d have to run through multiple canisters, but if one or the other truly came out ahead, you’d probably be reasonably safe in assuming that brand was better based on just one canister each.  The fly in the ointment is that the blends may vary batch to batch.  Still, an interesting experiment, and Olicamp has publicly posted their mix (75/25), so at least Olicamp should be reasonably close to their stated percentages.

HJ

It seems to me that canister gas is only slightly better than 95% ethanol for heat value once you figure in the weight of the can. Of course if you place it in a pot of water, then you cannot cook with that pot, either. Bob’s Strip will also add weight to a can along with any attachments. Dunno, it all looks like it is starting to break even at 32F and below.

Bob’s metal strip will work better at colder temperatures, but beware.  Too much heat, and KABOOM!

LOL, well I am familiar with the legendary Alpine Bomb!

But I have tested my setup in conditions that you would swear would cause an explosion and the stoves operated at a safe temperature, although they were starting to get uncomfortably warm and approaching the DoT mandated “safe” temperature of 122°F (50°C).

Those conditions were 80°F ambient, MiniMo and BRS running at full throttle for 30 minutes straight, canisters inside the cozies. I monitored the canister temps with 2 cooking thermometer probes inside the cozies and cinched close to the canisters. I also did regular “touch tests” of the tops of the canisters as well.

Bottom line, there is no way in heck these things are going to explode when used at temps of, say, 45°F and lower.

If you run it at full speed, you can see the effects of cold better, but either way works.  There’s an intermediate low temperature range where the stove works fine at low speed, but slows way down if you try to run at high speed.

If I’m using butane that costs $1.25 for 8 ounces and I can fill my canister to the amount I need, there’s rarely a time it matters if I’m running slower for better efficiency

I was just agreeing with Jim in general.  And everyone else : )

Propane is okay, but the amount of N butane is more important for determining the lower temperature limit.  If you’re going to use most of the canister by the end of a trip and you still want it to work, most of the propane will have boiled away so your lower temperature limit will be determined by the ratio of iso and N butane.  Propane works great on the first part of a trip or in inverted stove.

 Propane works great on the first part of a trip ….
I dunno about that as a general restriction. IF you can quickly get the canister to above 5 C every time then I think there will still be a reasonable bit of propane left at the end of the trip. But that does require some careful use and monitoring. If you start off with the canister warmer than the ambient – kept in pack or under quilt for instance, then you have a very good chance.

Cheers

Yes, Jim, the water does indeed boil at 201* F at my house (5440′ elevation).

For my upcoming test, I will set the flames at medium-low to medium, and I will let them run that way until one of them falters, or they both run out of fuel. I won’t be boiling any water. The key variable will be getting the flames of both stoves set exactly the same–probably a bit hard to do. We’ll see. Come to think of it, maybe I should do one 2-cup boil with each stove at first, to check the flame settings. Same stove and the same pot/lid (I happen to have two of each). If the boil times are significantly different, I could adjust one of the stoves and do a second boil. It shouldn’t take more than 3 boils to get the 2 stoves dialed in. Then I can get back into the house to warm up, and let the stoves burn.

By the way, I completely agree with what Bob says about the efficiency and safety of the Moulder Strip. When he first introduced us to his concept, I immediately made my own copy to try out. We collaborated extensively, traded parts, and each tweaked our setups in various ways. I haven’t “enjoyed” a sub-zero F day since I did my final modification, and I am looking forward to having a few come real soon. Late December is our local “muy frio” season. It’s funny, but I used to despise -15* F here, but now I get all excited when it happens. It gives me a chance to test stoves, winter clothing, etc. from the comfort of home!

ha, ha,…

same here, I always look forward to cold temps

except it’s maybe 20 F here

One more time, just for the Stovies…

Lol

Jim – do you have a good source for the Olicamp fuel?  I took a chance and placed an order with 21st-century-goods.com over a week ago and have yet to see any progress on the order or get any response to my emails.  Most of the online sources I have found look shady.

I typically don’t buy on-line because they want to charge so much for shipping, so I can’t recommend a site based on personal experience.  Liberty Mountain is the wholesale distributor of Olicamp Rocket Fuel.  You could call them, 800.366.2666, and ask for a retailer in your area or for a reputable on-line retailer.

HJ

Before I head out I calculate the number of boils we’ll need and then grab my current “in use” fuel canister and weigh it to determine the remaining amount of fuel and calculate how many boils it contains.  This lets me know whether I should bring another canister along or not.  Calculating boils per ounce and boils per canister at various temperatures, wind conditions, and altitudes using a JetBoil and JetBoil or Snow Peak fuel I get about 3.2 boils per ounce of fuel.  I’ve tested various other stoves that aren’t as good at wind protection and heat transfer and discarded them all in favor of the JetBoil.  Alcohol stoves with wind protection are good weight ratio at 3 days or less but I just use the JetBoil anyway since it boils water much faster.  On trips > 3 days the weight ratio is better with the JetBoil (Titanium).

<p style=”text-align: left;”>On trips > 3 days the weight ratio is better with the JetBoil (Titanium).</p>

as long as you are only talking about fuel weight and not total weight, sure. My 2 cents.

but I just use the JetBoil anyway since it boils water much faster.
Sometimes the power, speed and convenience of a canister stove outweighs (sorry about the pun) any slight weight penalties. HYOH.

When we stop for food, my wife wants her coffee NOW, not in half an hour.

Cheers

I’m impressed with all the math and calculations but have gravitated to a dumbed-down protocol.

Years of experience with MSR fuel and the Pocket Rocket stove has shown that my wife and I will use about 1 ounce of fuel per night on the trail.  I up that to 1.5 ounces for a margin of error.

So, for example, a 4 day trip would have 3 nights.  3 X 1.5 =4.5 ounces.  I then fish through our used cannisters and use the lightest one that has 4.5 ounces or more (net) of fuel.

We’ve never run dry and I don’t mind a little extra weight in this area.  Some extra instant heat could be a life saver.