Thread: refill your disposable canisters

Originally Posted by ROKTOY

https://www.elgas.co.nz/resources/el...pane-vs-lpg-nz

Thank you

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Originally Posted by GWH

Yes you do, I believe that LPG has a even more favorable mix of the two, like 60/40

You can get a mix from Filling Stations (not petrol stations) called propane plus!

Originally Posted by scottrods

I don't understand why you would do this?
Surely the canisters are a mix of butane and propane to work at altitude, but you don't get that mix from LPG.

I couldn't tell any difference between a can of "high altitude" mix and a can I filled myself and used @ 1700mASL in the snow.

Anyone got a link to a recommend filling adaptor?

so where do you get your hands on one of these? and maybe not a total cheap arse one but medium quality?

Originally Posted by birch

so where do you get your hands on one of these? and maybe not a total cheap arse one but medium quality?

Look back through the thread, a few including myself have posted up links.

cheers

Ok so I never had much luck with my one as it wouldn’t thread into the LPG cylinder enough so gave up on it.

Then today I stumbled upon this and have ordered one, will report once I’ve tried it. https://www.mtn.co.nz/product/gas-ca...refill-adaptor

Hi guys, I haven’t read though the whole thread but can I suggest you put the empty can in the freezer before filling. (Stuff moves from hot to cold) law of physics. And yes the full bottle needs to be upside down to get liquid out. Be very careful not to over fill as it needs space to expand.

Refilling camping canisters with LPG is extremely dangerous. There is a very good reason LPG and 100% Propane are stored in heavy steel vessels.

DO NOT DO WHAT THESE GUYS ARE DOING!

There are 3 main gases we use for cookers. n-butane, Isobutane and Propane. They all have different properties and we use them in different situations.

The boiling point of the gases are:
n-butane = -0.4C
Isobutane = -11.7C
Propane = -42C

As you increase the gas temperature above the boiling point of the gas the pressure inside the canister rises. At 20C n-butane is still pretty harmless and can be contained inside a plastic Bic lighter, you could not do this with 100% Propane. Have you ever seen one of those green steel gas canisters that Coleman makes? That's 100% Propane. That is what is needed to contain that gas.
So n-butane is no good for our needs and 100% Propane is no good due to the heavy steel vessels we would need to contain it. What we use is a mixture of Isobutane ( a chemically rearranged n-butane which lowers the boiling point) and Propane. A lot of gas canisters don't list the mix ratio anymore but it's around 80/20.

LPG in New Zealand is typically 60/40 Propane and Butane.

What happens when you fill a camping canister with LPG and your pot of boiling water overflows onto the canister below? Or you use a windshield around your cooker? These canisters are not designed to withstand the pressures of the higher ratio of Propane. You are literally risking your (or whoever is near the stove) life doing this guys. Youtube has some examples of what a camping canister explosion looks like - Do you really want to risk it?

The only way you should refill your camping canisters is with the same blend of gas it originally had in it. Since most manufacturers don't list the blend anymore the only real way to minimise the risk is to transfer from the same brand to the same brand eg. MSR to MSR. It's generally cheaper to buy gas in the larger bottles so this really the only reason to be doing this, or you want a custom amount inside a canister instead of two small ones you could take a 3/4 full larger can and save on the weight of the can material.

The correct way to do the gas transfer is to weigh your empty canister first and record the weight. Say it was a 230g canister and the empty canister weighed 150g. You would fill the canister until it weighed 150+230=380g this is the safe amount. Do not overfill. Put your donor canister (of the exact same blend of fuel) in warm (NOT hot) water and your receiving canister into an ice bath. Once the donor canister has warmed up you invert it and using the adapter you start to fill the receiving canister which is still in the ice bath. Let it fill for a minute or so and then weigh the receiving canister. Repeat until you reach your safe fill value. If you exceed the safe fill value vent the excess off outside or use a stove to burn it off.

I can post some links to further reading and a suitable adapter if anyone is interested to learn more. I would recommend any of you that have filled your canisters with LPG to vent them off.

Here's a picture taken from Kiwicamping website showing some typical vessels for the gases mentioned. Note the LPG and the 100% Propane are in heavy duty steel vessels.


Here's a video showing how camping style canisters are manufactured and tested. Note how they are tested in 52C water. Take a look on a canister some time it will state do not use them above 50C for Isobutane. https://www.youtube.com/watch?v=81lwc0L8Tfw

And finally a report of someone being injured by using a windshield around a gas cooker ( Can only assume it was regular Iso/Butane mix gas). The likelyhood of this happening is greatly increased with a higher percentage of Propane. Don't let it be you, your family or friends for the sake of saving a minimal amount of money.
https://worksafe.govt.nz/topic-and-i...burn-injuries/

Originally Posted by K95

Here's a picture taken from Kiwicamping website showing some typical vessels for the gases mentioned. Note the LPG and the 100% Propane are in heavy duty steel vessels.
Attachment 135432

Here's a video showing how camping style canisters are manufactured and tested. Note how they are tested in 52C water. Take a look on a canister some time it will state do not use them above 50C for Isobutane. https://www.youtube.com/watch?v=81lwc0L8Tfw

And finally a report of someone being injured by using a windshield around a gas cooker ( Can only assume it was regular Iso/Butane mix gas). The likelyhood of this happening is greatly increased with a higher percentage of Propane. Don't let it be you, your family or friends for the sake of saving a minimal amount of money.
https://worksafe.govt.nz/topic-and-i...burn-injuries/

Im not condoning refilling any disposable canister, but that work safe report tells us nothing.
What a waste of time, what can we learn from this incident?

Originally Posted by 2post

Im not condoning refilling any disposable canister, but that work safe report tells us nothing.
What a waste of time, what can we learn from this incident?

It's an example of how explosions and injuries happen. Most of us have used windshields with upright canister stoves before and got away with it. Using LPG inside a canister increases the likelyhood of an explosion by lowering the temperature at which it will explode. That's the takeaway.

A chart of Propane pressures means nothing because we don't know at what pressure the canisters will explode. They are tested with a certain mixture of gas at say 52C and labelled not to be used above that temperature. Putting a different mixture of gas in there invalidates that test.

The work safe report says the stove fuel was LPG but the gas canisters was butane.
What was it?
The only learnings we can take from it is don’t use portable stoves if you are an idiot of work for worksafe.