|A G-Works R1 Gas Saver adapter can help one avoid paying the "convenience charge" of small canisters.|
|A 100 gram canister of gas often retails for $4.95. That's a nickel per gram.|
|440 gram canisters for sale for $7.72|
Well, you can pay the big canister rate for small canisters. Yes, that's right, you can. You just need a G-Works R1 Gas Saver. The G-Works Gas Saver basically hooks up two canisters. When your 100 or 110 g canister runs out, you refill from a 440 or 450 g canister. Thus, you pay the 440 g rate for the convenient 100 or 100 g size canister.
You can also custom fill canisters to exactly the amount of gas you need for a given trip. Say you need approximately 12 ounces of fuel (about 340 g) for a given trip. Well, gas is only sold in the US in approximately 4, 8, and 16 ounce sizes (roughly 110, 220, and 450 grams respectively). If you want 12 oz of fuel, you have to buy 16 oz and carry an extra quarter pound of dead weight. Yes, you could flare off the gas, but that's kind of a waste.
Or, you could carry one 8 oz (about 230 g) and one 4 oz (about 110 g) canister, but remember a 100 g canister of gas weighs 200 g full and 100 g when empty. In other words, the canister weighs as much as the fuel. So, by carrying two canisters, you're carrying a lot more steel, and you're really not saving much weight by carrying one 4 oz and one 8 oz canister when compared to carrying a single 440 or 450 g canister.
For example, I took some full canisters, and put them on a scale:
|Size||Weight when full (g)||Weight when full (g)|
The difference between carrying 16 oz of fuel vs. 12 is only 33 g (1.2 oz) because of the weight of the canisters. The weights between brands of canisters may vary, but these weights should be illustrative. So, carrying 4 oz less in fuel saves me only about 1 oz in actual weight because of those darned steel canisters.
But what if I custom fill an empty 16 oz canister with 12 oz of fuel? The weight of the canister does not change, and any reduction in fuel equates to an actual one-to-one reduction in weight. If I fill with 4 oz less of fuel (113 g), I carry 4 oz less pack weight. Yes, a bit of fuss to save a quarter pound, but remember that if the average backpacker (who carries something like 80 to 100 items in their backpack) could save just 2 oz on average per item, their pack would weigh on the order of ten pounds less overall. Ounces are worth shaving wherever you can. And if you're already using the G-Works adapter to pay the 440 g rate for 110 g canisters, why not not save a few ounces of pack weight while you're at it?
Refilling canisters could be dangerous, very dangerous. I'm talking about permanent injury, loss of eyesight, disfigurement, and even death.
You will note that I am not a lawyer. I don't work for any company that could get sued here. I'm not some ninny in an office who doesn't give a dang about whether you live or die in the back country so long as his company can't be sued. I am just a fellow lover of the wilderness. Any warning I give you is realistic and sober. My warnings are not overblown silliness as are so many of today's legal warnings. I'm giving it to you straight. If you ignore me, you're a dumb ass, and I have little sympathy for you. Don't come crying to me if you didn't heed my warnings.
In my original post on refilling gas canisters, I listed a series of precautions. Read my original post on refilling gas canisters if you are thinking about refilling canisters of your own. Please do your homework before you try something like this. If you do try this, there's a certain danger to it, no matter what. You're working with highly flammable, explosive gasses. You've been warned.
Transfer from Like to Like
Not all canisters are created equal. Some are stronger than others. When you take canister gas from one canister and transfer it into another, you want to make sure that the receiving canister can handle the resultant pressure. The ideal way to do this is to "stay within the brand." By "within the brand," I mean transferring Jetboil to Jetboil, Primus to Primus, etc. If you transfer gas from a larger canister to a smaller canister of the same brand, you already know that the smaller canister can handle the pressure from that blend of gas. Note: Some companies, Primus in particular, have different blends: Summer blend, winter blend, etc. For companies with different blends, use a donor canister of the same blend as the receiving canister originally held.
If you can't find a donor canister of the same brand as your receiving canister, you can check on the company's website what blend (percentages of propane, isobutane, and n-butane) the canisters held to insure compatibility, but it's best to stay within the brand if you can. Note that some companies do not publish their blend's percentages and that percentages can change over time.
Basically though, if you transfer from like to like, you minimize the risk that the receiving canister can't handle the pressure.
Custom filling/refilling is actually fairly simple. I'll list the instructions below.
Before you start, weigh the empty canister. The weight of the canister + the amount of gas the canister originally contained is the maximum safe total weight of the canister. For example, if your receiving canister weighs 116 g when empty and originally held 220 g of fuel, then your maximum safe weight is 336 g (116 + 220 = 336). The amount of fuel your empty canister originally held should be printed on the label of the canister. If you can't read the label, get a different canister. Only use canisters in good condition when refilling.
|My receiving canister weighs 116 g when empty.|
1. Place the donor canister into a pan or pot of warm water. I said warm water, not hot water. Do not immerse a canister into hot water. Hot water could cause the internal pressure of the canister to exceed the rating of the canister which could cause the canister to burst. Do not put the canister in the pan while the pan is on a stove. What if you left the stove on for a minute and got distracted? Take the pot off the stove, and then put the canister into the warm (not hot!) water.
2. Prepare an ice bath in a container that can hold the recipient canister and some water with ice. You don't want the level of the water to exceed the height of the canister. Keep the connector and Lindal valve area of the canister dry.
3. Close the valve on the G-Works Gas Saver adapter.
4. Screw on the empty receiving canister to the Gas Saver.
5. Take the donor canister out of the warm water, dry it off, and screw the donor on to the other connector on the Gas Saver.
6. Place the receiving canister into the ice bath taking care to keep water out of the connector and Lindal valve area.
|A G-Works Gas Saver properly hooked up with two canisters.|
The donor canister is on top. The receiving canister is on the bottom, in the ice bath.
Take care to keep water out of the connector and Lindal valve area of the receiving canister.
When you open the valve on the Gas Saver, you should hear gas flowing from the full donor canister into the empty receiving canister.
8. After you've let it run for a minute or so, close the valve, take the receiving canister off the G-Works adapter, and weigh the receiving canister. While you're weighing the receiving canister, put the donor canister back into the pan of warm (not hot!) water. Repeat steps 6, 7, and 8 until the receiving canister is full. Do not exceed the maximum safe fill weight of the canister.
|Success! My canister which weighed only 116 g when empty is now clearly full of gas,|
BUT my maximum safe fill weight is 336 g. I need to vent or burn off 10 g.
That's really all there is to it. With the above described techniques and the G-Works Gas Saver, you can refill or custom fill smaller, lighter, more convenient canisters using larger, cheaper (per gram) canisters.
Be safe and read all the cautions, please. This is good stuff, but you do need to be careful.
Take care and happy stoving,
Appendix I – Custom Fuel Blends – DANGER
Danger. We now depart from anything that might be considered reasonably safe. You're completely on your own here if you do this. I'm not recommending this to you; I'm just saying it's physically possible. Just because you can do something doesn't mean that you should. Note that I myself have not done this. I think it's just too danged dangerous. Try it at your own risk.
What am I talking about? Well, remember my recent post on the other G-Works adapter, the G-Works Propane adapter? With that propane adapter and the G-Works gas saver adapter, you could add propane to a backpacking canister.
Why would you do this? Well, for cold weather. Recall that propane is your best fuel for cold weather. In the US, the most propane content you can get in a backpacking canister is about 25% or 30% depending on whether it's mixed with isobutane or n-butane. You could boost that percentage to 35% or 40% if you combine the G-Works propane adapter with the Gas Saver adapter. No, I don't have any photos of this combination. This is potentially quite dangerous and I have not tried it.
If you do add additional propane to your backpacking canisters, add the propane last. Why? Well, if you add propane to an empty canister, then, at least for a while, you've got 100% propane in there. That could be bad, very bad. Those little lightweight (comparatively) backpacking canisters cannot handle the high pressure of 100% propane. DON'T DO IT. I'm not sure you should add propane to a backpacking canister at all, but if you do, add the propane last, after the canister has a factory blended fuel mix in it.
Never fill a backpacking gas canister with 100% propane.
|A stove and pot destroyed by a canister filled with 100% propane.|
Note how the canister has burst.
NEVER fill a backpacking type canister with 100% propane.
|A stove and pot destroyed by a canister explosion.|
NEVER fill a backpacking type canister with 100% propane.