View Full Version : Refilling Gas Canisters
hikin_jim
01-20-2012, 02:39
Of course it's possible to refill backpacking type gas canisters. But what are the real risks? What are the practicalities? Is it even worth it?
https://lh3.googleusercontent.com/-3tuSvq96X5U/TxjuUuhcY8I/AAAAAAAACmI/u1yEMuenor8/s800/P1090679.JPG
Please join me as I explore Refilling Gas Canisters (http://adventuresinstoving.blogspot.com/2012/01/gas-canister-refilling.html)
HJ
what about refilling them using 100% propane from a large out door grill canister.
4eyedbuzzard
01-20-2012, 18:32
what about refilling them using 100% propane from a large out door grill canister.They would likely rupture (and explode if an ignition source was present) as propane boils at -44° F. Butane boils at 31° F for comparison, isobutane at 11° F. The pressure would be too much for the canisters to handle.
bamboo bob
01-20-2012, 18:34
but why would you bother?
With the right connectors you could theoretically refill propane into the propane coleman canisters, but would it be worth it? Maybe you could get your local propane supplier to do it since they have a little more experience with it.
Slo-go'en
01-20-2012, 18:46
Is it even legal? Not that that matters much...
On the practical side, with the system pictured above, you'd never be able to completely transfer all the gas from one canister to another because the preasures will always end up equal between the two. If the volumes of the two cansisters are the the same or roughly equal, you'll end up with two half full canisters to start and it goes down hill from there.
hikin_jim
01-20-2012, 19:30
what about refilling them using 100% propane from a large out door grill canister.4eyedbuzzard is correct. Propane has quadruple (at 70F) the vapor pressure of butane. A BP'ing type canister can't handle it.
HJ
hikin_jim
01-20-2012, 19:32
but why would you bother? Why bother to fill with 100% propane? Cold weather performance. But let me stress that you can't. A BP'ing canister can't handle 100% propane. WAY too high pressure.
But if you could, it would work a lot better. Butane stops vaporizing below 31F. Propane continues to vaporize down to -44F. HUGE difference. That's why a lot of people use white gas for cold weather. Canister gas has problems.
HJ
hikin_jim
01-20-2012, 19:37
Is it even legal? Not that that matters much... The Dept. of Transportation regulates interstate commerce. Their regs forbid (as I understand it) transport of refilled canisters of this type. Therefore, it would be illegal to transport across state lines.
On the practical side, with the system pictured above, you'd never be able to completely transfer all the gas from one canister to another because the preasures will always end up equal between the two. If the volumes of the two cansisters are the the same or roughly equal, you'll end up with two half full canisters to start and it goes down hill from there. Well, actually, that's not quite right. Think about it. The majority of the fuel is what? It's liquid. If it were two tanks of vapor, then what your saying would be absolutely true. You'd get equalization, and then transfer would stop. However, with liquid it's possible to transfer far more. I've been doing it for about two years. Normally, I can transfer all but a few grams.
HJ
I have a friend that made a valve system to fill backpacking canisters with whatever the fuel is that comes in 1lb Coleman canisters. He'd have the backpacking canister on the bottom and Coleman on top but inverted and would guesstimate when the bottom one was full. That worked great until one day his wife's pack exploded while hiking in the heat of the sun. Thankfully, she wasn't injured and is not a cripple.
My suggestion: pay the $4.
4eyedbuzzard
01-20-2012, 19:49
I have a friend that made a valve system to fill backpacking canisters with whatever the fuel is that comes in 1lb Coleman canisters. He'd have the backpacking canister on the bottom and Coleman on top but inverted and would guesstimate when the bottom one was full. That worked great until one day his wife's pack exploded while hiking in the heat of the sun. Thankfully, she wasn't injured and is not a cripple.
My suggestion: pay the $4.Wow. She's lucky. Sounds like he filled it with pure propane. You would think people clever enough to make adapters and such would know better.
Wow. She's lucky. Sounds like he filled it with pure propane. You would think people clever enough to make adapters and such would know better.
He wasn't called The Professor ('95,'00) for nothing. or maybe he was! ;)
You can punch holes in the old ones and recycle with scrap metal which is probably the "greenest" thing to do with them - if you like re-fillable, I would suggest just using a liquid fuel stove, but it is a cool idea.
hikin_jim
01-20-2012, 20:23
Wow. She's lucky. Sounds like he filled it with pure propane. You would think people clever enough to make adapters and such would know better.Yes, she was lucky. Maybe I should mention:
Do NOT fill backpacking type canisters with 100% propane under any circumstances.
HJ
yes, she was lucky. Maybe i should mention:
do not fill backpacking type canisters with 100% propane under any circumstances.
hj
you scared meeeee!
hikin_jim
01-20-2012, 20:47
you scared meeeee! Good! :)
Seriously though, refilling backpacking type canisters with 100% propane IS scary. The lightweight steel can't contain the pressure of propane. At 70F, propane has quadruple the pressure of butane. You need a big, heavy-duty steel container like the 16.4oz/465g Coleman containers. 100% propane + backpacking type canister = KABOOM. Not good.
HJ
Seriously ppl dont hurt yourself over saving a few cents.
hikin_jim
01-21-2012, 01:03
Seriously ppl dont hurt yourself over saving a few cents. Refilling with 100% butane is reasonably safe if your careful -- as safe as working with white gas for example. Refilling with 100% propane is extremely dangerous if you're putting that propane into a backpacking type canister.
HJ
Slo-go'en
01-21-2012, 14:19
Well, actually, that's not quite right. Think about it. The majority of the fuel is what? It's liquid. If it were two tanks of vapor, then what your saying would be absolutely true. You'd get equalization, and then transfer would stop. However, with liquid it's possible to transfer far more. I've been doing it for about two years. Normally, I can transfer all but a few grams.HJ
The reason it's liquid is because it is under considerable pressure. Gas can be liquified in two ways - make it really cold or put it under a lot of pressure. Unless a mechanical pump is used, transfering a gas from one container to another will continue only until the pressures are equal in both. The gas will remain liquid as long as the pressures remain high enough in both containers.
The gas container is "empty" when the pressure of the gas inside the container is the same as the atmospheric pressure. That's why throwing an empty gas canister into camp fire isn't a good idea. There is still some flamable gas inside and once it gets heated up by the fire, the canister can explode, creating a nice little fire ball.
Slo-go'en is right, once the pressure equalizes, the filling stops. However, just chill the canister being filled (ice water bath is best) and warm the filling canister (in the sun perhaps). With a little patience, you can get a canister 80% to 90% filled. Okay, a lot of patience!
hikin_jim
01-21-2012, 16:02
The reason it's liquid is because it is under considerable pressure. Gas can be liquified in two ways - make it really cold or put it under a lot of pressure. Unless a mechanical pump is used, transfering a gas from one container to another will continue only until the pressures are equal in both. The gas will remain liquid as long as the pressures remain high enough in both containers.
The gas container is "empty" when the pressure of the gas inside the container is the same as the atmospheric pressure. That's why throwing an empty gas canister into camp fire isn't a good idea. There is still some flamable gas inside and once it gets heated up by the fire, the canister can explode, creating a nice little fire ball. Well, all I can say is that when I transfer from a 227g canister, when I weigh the canister afterwards, it's usually about 220g lighter and the receiving canister is 220g heavier. Maybe the gas didn't read the science text book? :)
HJ
Wise Old Owl
01-21-2012, 16:20
Nice find Hiking Jim, what stops me is the fiddle factor and the mention of hours.... I just don't shoot through the canisters that fast.
However I do refill the mini Propane cansisters and carry pressurizing caps to prevent leaks. I use an old Propane cylinder that I have not thrown out and a beer refigerator to chill the small cylinders. I use them for campgrounds for the last 10 years. They make power outages a thing of the past, cooking inside the house with a window open. I figured out how to get past the OPD law and I am happy.
I would never put propane into a butane cylinder.
Wise Old Owl
01-21-2012, 16:23
but why would you bother?
My guess is that you don't go on a extended hike with a slightly used cylinder.
hikin_jim
01-23-2012, 13:41
Slo-go'en is right, once the pressure equalizes, the filling stops. However, just chill the canister being filled (ice water bath is best) and warm the filling canister (in the sun perhaps). With a little patience, you can get a canister 80% to 90% filled. Okay, a lot of patience! I thought of an analogy that may be helpful: think of two bottles of water, connected by a hose. Put the two bottles next to each other, with both bottles right side up, and nothing flows. Now turn one bottle upside down and suspend it above the other bottle. The water flows from the upper bottle to the lower. Why? Gravity. Yes, there is air pressure in the lower bottle that blocks the transfer to some degree, but what happens in practice is that the air is able to bubble up through the liquid water, and so the transfer works fairly well.
In like manner, if you had two gas canisters side by side, both right side up, no transfer would occur if the vapor pressures were equal. But suspend one above the other like so:
https://lh3.googleusercontent.com/-3tuSvq96X5U/TxjuUuhcY8I/AAAAAAAACmI/u1yEMuenor8/s800/P1090679.JPG
and the liquid will flow one from another. The vapor will bubble up through as the liquid flows, much like the water example, above. In actual practice it differs a bit from brand to brand because of variations in the internal vapor feed tube. With the brand shown, Mega1, it works as described (liquid flowing).
HJ
hikin_jim
01-23-2012, 13:42
My guess is that you don't go on a extended hike with a slightly used cylinder.It is really super convenient to be able to top off a canister. A canister with only 1/3 left isn't really suitable for the trail. With refilling, I just top it off, and the canister is as useful to me as the day I bought it.
HJ
But does it stay liquid during the transfer, because it seems like it wouldnt. I agree with the poster that said the empty chamber would cause the liquid to become gas, just as it does when released out of the bottle into the air.
hikin_jim
01-23-2012, 15:15
But does it stay liquid during the transfer, because it seems like it wouldnt. I agree with the poster that said the empty chamber would cause the liquid to become gas, just as it does when released out of the bottle into the air.Hi, Tomp,
I know that if I hook things up and leave it overnight, I've got a full canister in the morning. That's with Mega1 brand.
With some brands (GasOne), I've had to put the receiving canister in the freezer and warm the donating canister to get it to work properly.
Perhaps it will vary with conditions. Certainly butane will remain liquid if the temp is <32F. I haven't tried cold transfers yet though.
HJ
RetroGear
01-23-2012, 17:36
I have a friend that made a valve system to fill backpacking canisters with whatever the fuel is that comes in 1lb Coleman canisters. He'd have the backpacking canister on the bottom and Coleman on top but inverted and would guesstimate when the bottom one was full. That worked great until one day his wife's pack exploded while hiking in the heat of the sun. Thankfully, she wasn't injured and is not a cripple.
My suggestion: pay the $4.
So, is she still his wife? Or his ex-wife? :)
Seriously, it isn't worth it to save a measly 5 bucks. One, I almost always hike when the temps are <60, and usually <40, so butane isn't a great choice; two, even though most of the backpacking canisters are made and filled in Korea, I can pretty much assume that they know more about filling canisters than I do; and three, if I do have a kaboom (and assuming I wasn't negligent myself), I can sue the Korean manufacturer, the importer/relabeler (such as MSR), and the store I bought it from.
I stopped using canister stoves because it frustrated me not knowing whether my canisters were half empty or completely empty or whatever. I'd try to mark them after each trip (# of uses) but that got annoying so I just switched to alcohol stoves. To me not knowing whether canisters were full or not was much more of a hassle. I can understand why someone might want to refill them but I don't think it's worth it. If you do, follow the other guy's friend's example and have a buddy .. or your spouse... carry the stove.
hikin_jim
01-23-2012, 18:12
I stopped using canister stoves because it frustrated me not knowing whether my canisters were half empty or completely empty or whatever. I'd try to mark them after each trip (# of uses) but that got annoying so I just switched to alcohol stoves. To me not knowing whether canisters were full or not was much more of a hassle. I've actually got some ideas on that: How much gas do I have left? (http://adventuresinstoving.blogspot.com/2011/07/how-much-gas-do-i-have-left.html)
HJ