New to this site and really enjoying the wealth of information here. Just read Will Rietveld's stove performance comparison and a couple of points have struck me.

Firstly no comment on apparent higher gas use by remote rather than integrated gas stoves. My own experiments , I haste to say crude in comparison, have lead me to believe that very small burners that direct their flame mostly upward are more efficient at heating our small pots rahter than do-nut ring type burners, this may explain the differences here.

In a constant search for lighter weight I have been using the narrow tall gas canisters that are designed to fit into Asian table top gas stoves. These are lighter by 1 to 2 oz c.f. conventional canisters and contain the same amount of gas, and can now be bought c blended fuel. They are also cheaper. Kovea make an adaptor to use thes canisters if you have a stove designed for remote Lindel valve canisters, but it is heavy.

I have been experimenting c stove building and have made a fitting to tap directly into these canisters. The device weighs 1 oz and includes a metering valve which brings the whole weight to 4 oz for remote canister stove , 4.5 oz if pre heating tube fitted.

However I think the most stunning gain is the filling of the "non-refillable" canisters. This is easily done and has enormous advantages.

Firstly there are never any more partly used canisters . There is an endless supply of used once nearly new empty canisters from other backpackers. The price per canister drops to 40 or 50 cents per fill and means gas becomes a very economical fuel. For shorter trips only the fuel needed needs to be carried i.e intentionally part filling the canister. If your BBQ bottle contains blended [ propane + butane ] fuel then cold weather performance is on a par c commercial cartridges.

With what do you refill them?

They can be refilled from your BBQ gas bottle. Need to make an adaptor up which is a one off cost but after that its a winner all the way.

I'm not sure I follow... are you filling isobuate/propane cannisters direct from a propane tank for your grill? How do you control the fill rate and heat? How do you make sure you don't blow up the cannister? Do yo invert the grill tank to ensure liquid fill? Or have I completely misunderstood you?

Mark

Can you explain what you mean by a fitting to tap directly into the canisters?

Is this a valve that is puncturing the canister, i.e. tapping in through the metal sides or is it an attachment that is connecting in some way to the existing valve mechanism?

Hi Mark-

Sound like some you've got some cool ideas!


One caution though...

I'm not sure where you're located, but here in the US, BBQ bottles contain pure propane. Due to propane's much higher vapor pressure than butane, it is *EXTREMELY DANGEROUS* to refill a canister designed for butane or propane/butane blend with pure propane.

Please be careful out there.

Cheers,

-Mike

Edited by MikeMartin on 07/23/2006 15:07:34 MDT.

Dylan, Scott, Summit CO, Mark is clueless as to what it takes to do this and it is way to dangerous to even think about. If you are thinking about this as a way to save a small amount of money you better make sure you have really good medical and burial insurance. You will need it.

You are playing with a bomb.

I can show you just enough to see it can be done but I don't think any of you all have the machinery or the skills to make the necessary fittings. If you were that smart you would never go there.

Bill,

I had no intension of trying to refil a canister. I use an alcohol stove and have done for years and have no intention of changing. It did strike me as extremely dangerous although I have no experience / data to quantify that thought other than common sense.

I asked the question because I couldn't visualise what Mark was describing other than getting the idea about refilling the canister. I'd still like to know what mark meant about tapping.

I'll definitely be keeping my arms and legs attached to my torso though, thanks very much.

Hi Scott,

It is a interesting question and one that was talked about here within the last year.

It is just one of those things that is so dangerous that I wanted to get the notion out of some ones mind before they came up with a scheme they thought might work and have a terrible accident.

I am surprised Roger Caffin didn't beat me to a reply.

Mark might be thinking that by tapping on the bottle he would hear a difference in the sound at the full line.

Bill,

That is kind of what I was figuring... that he was on a path to a possible BOOM. (onto shrapnel hitting something, sparking, suddenly you have a FAE... then the main tank starts burning till you get a bleve and you loose the house too).

Impressive work you've done there. I could get my friend to machine something similar but I use esbit. Seems like it might hold to some extent unless it got warm (as during filling). Seems quite dangerous though because AFAIK stove cannisters don't have rupture discs... I'd be curious to know more of your experience(for the sake of knowledge).

I was also wondering about the brunton fuel tool that someone mentioned for filling refillable lighters from near empty isobutane/propane cannisters... in theory it would virtually all isobutane, but the isobutane has a higher vapor pressure than the butane but nowhere near the difference between butane and propane. Seems that it would hold unless it got warm... then POP. I'd be less worried about a cracking plastic case but then you'd lose your lighter.

Edited by Summit on 07/23/2006 21:35:02 MDT.

Summit CO,
I didn't make what you see in the picture.

I like the safety and dependability of my store bought gas canisters. My preference is the Coleman PowerMax canister with one of my lighter weight Xtreme Stoves. The PowerMax is a lighter canister and the empty aluminum canister can be used for a number of different things.

My latest stove is a wood / PowerMax powered combo stove. Safe, dependable and light enough.

I think the way to check that the proposed system is sound, is by holding a lighted match along all the junctions, seams, and fittings. I think it is also an effective way to not pass on your genes to another generation.-Scott

Thanks Mike for pointing out that BBQ gas in the Usa is nearly 100% propane. I live in the Southern Hemisphere and LPG [liquified petroleum gas] is predominantly butane.

However you can buy the " Asian " canisters [ does anyone know their proper name? ] with a blend of 70 butane 30 propane and these canisters are structurally identical to those containing butane only. I suspect that these canisters can cope with a higher percentage of propane but we need a physicist to comment on the partial and total pressures of a gas mixture.

I'm sorry I chose my words poorly when I talked of tapping into the Asian canisters. I have made a stainless steel fitting which clips into the top of these canisters and then rotates 90 degrees to lock. The spigot on the canister seals to the underneath of this with an 0 ring and on top I have mounted a miniature needle valve [ Clippard mnv 4 k ] which is much smaller and lighter than anything the manufacturers use.

There is a big variation in canister cost down here. Powermax cost $15 Lindel valve canisters $7 and Asian $2-3 . I see little point in using Powermax as both the last two types of canister give identical performance to Powermax when inverted. From the recycling point of view there is no difference either as steel is recycled here also. I have fitted my liquid feed stove with a clear hydrocarbon-safe hose from a Hobby shop, and when I invert the canister can watch the liquid flow through the tube . Cool !!

I made the pre-heat tube out of 1/8 inch refrigeration copper capillary tubing. This is very thick walled and seems to work well. I wondered why manufacturers used a stainless wire in the feed tube and concluded it was to reduce the internal volume of the feed tube to reduce wasted fuel. Does any one agree? My feed tubes are too small and therefore do not require this by my calculations there is less than a gram of LPG in the tube.

I've been filling canisters for about 5 or 6 years now. The picture posted by Bill for the device is essentially correct but has two mistakes. Firstly the connecting tube is too long- 3 to 4 inches is plenty and the canister is in the wrong position. It ,along with the tube needs to be rotated 180 degrees so the canister is BELOW the BBQ bottle. Gravity then does the filling. To do this means you must place the BBQ bottle upside down on the side of a bench.

I fail to see where the danger is . The BBQ bottle cannot explode , nor can the canister provided you do not overfill. There is a minute amount of leakage when filling but no more than occurs when attaching your stove. There is no heat generated of course the canister cools slightly due to the slight gas leakage. I use electronic scales and knowing the cylinders empty weight can fill to within 2 grams.

I was initially concerned at the possibility of hidden internal corrosion. I cut a few empty canisters open and found they are VERY heavily plated inside. I therefore use the premise that if the outside is in good condition then the inside is almost certainly even better .

Ther is a setup cost in making the filling adaptor of course. The thread on the Lindel valve is an oddball no doubt carefully chosen that way by the manufacturers, I think Roger Caffin on his Australian site identified it but as no taps are available it doesnt matter as any machine shop can match it. The cost of the LPG drops so sharply when purchased in a BBQ bottle that the canisters almost become free for life [ albeit a tragically short life as opined by members of this forum ]

When I can persuade my son to teach me how to post pictures I will do so if anyone is interested.

Hi Mark, You said one thing that might explain why you are doing this. The fact that you have to pay $15 for the PowrMax canister when I can buy them everyday -$2.99 for the large - 300 gram size.

For me the deciding factor was cheap price and safety vs cheaper price and dangerous.

I have a tap and die set that match the thread on the Lindel valve.

Edited by bfornshell on 07/24/2006 16:09:50 MDT.

Mark, Is this more like you are talking about. This is just a cut and paste version of the other picture.

Edited by bfornshell on 07/24/2006 17:32:13 MDT.

The stainless wire inside the preheat tube was explained to me to be a cleaning/clog-clearing device; like a pipe cleaner.

My stove seems to perform the same with or without this wire.

On a similar note, has anyone developed an adapter to allow 1-lb or 20-lb propane bottles to be used with remote canister stoves? Going car camping with the gf for a week and not looking forward to burning up all that expensive butane!

thanks
Brian

Will the cannister stove handle that?

You'd better leave the cannister stove on and control the flow from the regulator/valve on your propane tank so you don't ever fully pressurize the stove's tubing and blow a fitting/gasket/valve.

"Thanks Mike for pointing out that BBQ gas in the Usa is nearly 100% propane. I live in the Southern Hemisphere and LPG [liquified petroleum gas] is predominantly butane.

However you can buy the " Asian " canisters [ does anyone know their proper name? ] with a blend of 70 butane 30 propane and these canisters are structurally identical to those containing butane only. I suspect that these canisters can cope with a higher percentage of propane but we need a physicist to comment on the partial and total pressures of a gas mixture."

I'm too lazy to run the exact numbers, but what you're indicating is essentially correct. Pure Butane has a significantly lower vapor pressure than an iso / but mix. So, if a canister is capable of dealing with iso / but it should handle pure but just fine.

"Mark, Is this more like you are talking about. This is just a cut and paste version of the other picture."

Bill, I believe you have that correct. The reason it would need to be that way is to ensure that the canister fills with liquid butane rather than vapor butane.

Just like water, liquid butane will 'seek it's own level'. So, the original pic won't force liquid into smaller tank unless the liquid level in the tank is higher than the small tank (well, technically it will force liquid but that liquid will vaporize as it 'climbs' the fill tube). Basically liquid will climb to whatever level in the fill tube matches the current liquid level in the tank.

In the case of the inverted (small tank much lower than the big tank) pic, the entire small tank and tube is below the big tank and therefor will be full of liquid.

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