Carl-

Honestly, I could not even tell you where I would try and go to buy pure butane or propane-butane (isobutane) mix here in town.

Supposedly Asian food markets and camping shops have it for stoves but, neither around me do.

So, with that said, I check Wal-Mart (largest US retailer) to see what they have. Apparently, they do have it for torches? And apparently at my local store (it is next door to my meths/alcohol supplier)

http://www.walmart.com/ip/Ronson-Multi-Fill-Butane-42g/17133680

...and my Meths supplier has it so.

http://www.lowes.com/pd_332077-717-1764293_?PL=1&productId=3340980

Did not know of the torch use, most are pure propane or (perfect for silver soldering!) MAPP gas.

Now, the quality or grade....or if it is PURE butane, I will go over and check sometime this weekend.

OK, MSDS for each of the two, for the Ronson brand:

http://www.ronsonusa.com/pdfs/msds/Ronson_Butane_03012010_MSDS.pdf

Chemical abstract # 68476-86-8 = a mix of butane and propane.

Now for Bernz brand:

http://www.bernzomatic.com/Portals/8/Resources/2011-MSDS/Eng-Butane-MSDS-6-11-11.pdf

The first CAS is for Butane, but the second chemical abstract # 75-28-5 is isobutane (isomer/compound) of butane.

So neither are pure butane....

I suspect most "Butane" fuels are mixtures. A fuel doesn't really need to be pure, it just needs to burn cleanly. Most seem to be 75%-80% butanes with the balance mostly propanes. And the propane would make it burn a little hotter.

The Bernzomatic is pure butane- it is a mixture of two isomers of butane. An isomer is not a different compound; it is the same specie with a different molecular arrangement, but it's still butane.

The "problem" with mixtures was not purity (excluding cold weather operations) involving propane, but increased pressures and tank failures.

Case in point Accucrarft: http://www.accucraft.com/manuals/Accucraft%20Fuel%20Tank%20Recall.pdf

And RH here: http://www.roundhouse-eng.com/tech.htm#gas

Back about five plus years ago there were some interesting failed tank photos posted on some of the forums.

The positive to all this is the problem has been identified and the tanks improved accordingly to allow for the mixed gasses, at least by these two builders/importers.

Paul, another thought for a DeWinton type loco: there is another geared live steam loco that has had some positive reviews by owners and press, the Mamod Brunel:

http://www.youtube.com/watch?v=JHmlCPxFo1o&feature=player_embedded

The reviewer, Chris Cairns, used to post on the Mamod forum regularly and has quite a collection of Mamod and Jane/Janet locos.

Now, as he points out in his review, the problems identified (single bung in boiler and sightglass location) have been changed. Case in point is the old review:

http://www.mamod.co.uk/downloads/Garden_Rail_Brunel_Review.pdf

Positives over the Max would be fixed cylinder and reversing ability (slip centric however, so one has to move the wheel to swap directions), sight glass, pressure gauge and ceramic gas burner from the factory, (Max these are options) and an additonal bung where one could add a goodall valve (and a proper pop safety valve!) from Dream Steam or PPS.

http://www.dreamsteam.co.uk/mss-mamod-upgrade-parts.html

http://www.pps-steam-models.co.uk/index.htm

Downfalls like the Max are being oversize/scale for a DeWinton in G/16mm scale and the tiny lubricator on the cylinder itself.

Downfall unlike the Max is the cylinder on the outside Vs inside as on a proper De Winton.

May be another option, but it is a bit more in price...but with more kit.

Thanks again for all the information guys! Cant't say it makes it easier to choose but at least I know some
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