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Butane Can Leakage

5720 Views 4 Replies 4 Participants Last post by  Semper Vaporo
Has anyone else had problems with valve stem leakage in the nominal 8 oz Korean butane cans? I have tried two different brands now, one with a flat valve tip and one with a rounded tip. Both sometimes spew liquid butane from around the valve steam when the valve is pressed. Once the stem is chilled by evaporating butane, (usually when the top adapter seal is initially crooked when charging an engine) the leak will usually continue when the valve is depressed until things warm up thoroughly. I assume something in the packing is shrinking and allowing leakage. They have not yet leaked when the can is in it's horizontal, notch up, stove position.

Is there a certain position of the valve travel when a seal occurs? I have not been able to find a repeatable pattern yet.

Also, I see that although the Accucraft adapter is designed for these cans, the adapter seal is worse than the fit going direct to Miss Ida. It seems the nipple end of the adapter is slightly larger than the engine tank fittings.
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George, you have come up against one of the weakest areas in the whole hobby. I've tried all kinds of different cans and adaptors some have advantages over others. I would recommend keep trying various combinations until you find something that works for you. I've even seen variations in one manufactures cans from one run to the next (including the primus isobutane). I'm sure others can give their two bits. You will find that there is often a fair amount of leakage, which is why we need to stop fueling long before the alky burner comes rolling our way.
Dave's right. Latest SitG has an article/review different can adapters, some better than others. Technique with cans can help. No great loss to loose some gas. Just fill your tank in a open area, with the wind blowing away from the tank, do not block the wind with your body. Best, gas fill away from the running track, last before carrying loco to the running track.
My question had little to do with adapter issues. The leakage I saw was clearly internal to the can itself, since it continued when I used a piece of rubber to tightly seal the tip while depressing the valve. No engine was then involved nor any adapter. I had already determined that this style can has an internal 90 degree bend which allows only gas to flow when horizontal with the notch up in the portable stoves that use them. So they never deliver liquid when installed in the intended stoves, which I also have. Therefore the manufacturers probably do not test for seals with liquid delivery. I have not seen this with either the 6 oz lighter fuel cans (King, Lucienne, etc.) or with the promix Lindahl style cans. But then both of those style cans are sometimes or always used for liquid delivery.

At first I thought it was just the usual alignment caused leakage when everything is not lined up perfectly or a seal is dirty, but this is different. In all cases thus far, the valve leaked ONLY when depressed and all cans worked properly later after warming up. And yes, all tests were made cautiously in clear air. I still remember from 50 years ago what can happen if a propane torch is cross threaded - no damage or injuries, but far too much excitement.
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I had a can of cooking oil spray leak after just one use, but since I don't use it often, I didn't know it until nearly a week later when I opened the cabinet and discovered the 1/8" of oil on the shelf and the one below and several cardboard boxes of baking soda, rice, macaroni, etc. were soaked in "butter flavour" oil.

As for your problem it does sound like maybe there is moisture in the gas that is freezing at the valve seat and holding the seal open, but that seems like it might be self perpetuating in that a leak would just keep the area cold and the frost would never melt to allow the seal to be made.

If you put your hand over the area to warm it, does it re-seal occur sooner?
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