Question about canister fuel.

Hi Thomas,

This page from Roger Caffins FAQ site has some good information about canister pressures, temperatures and volumes

http://www.bushwalking.org.au/FAQ/FAQ_Mixtures.htm

Tony

Thanks a lot man. I've got a really slick UL remote canister stove idea I've been tossing around and I'm trying to figure out the viability of my idea.

> I've got a really slick UL remote canister stove idea I've been tossing around and I'm trying to figure out the viability of my idea.

Well, this is THE place to talk about it!

Cheers

I want to make a single 6061 AL block as the base for the burner itself. I'm thinking about running a line into the block. From there feed into the block then out the other side into a preheat tube that'll loop over the burner then back up the center to the jet. Anyone have suggestions for a really lightweight line that's resistant enough to heat to run it straight into the block and inside of the windscreen? I'm leaning towards seeing if a bicycle hydraulic line designed for a DOT system will work. I'm trying to find heat specs on various lines I have access to as well as get an idea of what temperatures it might be subjected to. My stand design is a neat triangulated setup that I want to make out of Ti rod. I'm thinking about replacing one of the supports with a Ti tube to get the line further away from the stove. It would be great if I could integrate those 2 pieces together if I had to. Ideally though I'd find a really light line that I could run straight to the block.

Hi Thomas

Sounds good. Can I suggest you wander through the MYOG sections looking for postings by Tone Beasley, Bill Fornshell and myself – this will bring you up to speed over what several of us are doing along those lines. This applies to both stoves and pot stands.

This is NOT meant to be a damper on your efforts – rather it is meant to add just a wee touch of competition!

A suitable material for the preheat tube, if I understand you correctly, would be so-called 'flexible' SS hypodermic tubing.

Cheers

I've read some threads by you guys. I'm not talking about the preheat tube. I'm trying to figure out a good material for the fuel line itself.

Thomas,

You might investigate thin-walled fuel injection tubing. It would seem to have the appropriate characteristics without being too stiff or too heavy.

Anyone know of any heat and solvent resistant silicone tubing? I think that would be a really good option.

I found a nice PTFE tubing I think will work.

Here's the specs:

PTFE
Hardness, Shore D 50-65
Tensile Strength, psi 3000-5000
Elongation at Break, % 200-400
Brittle Temperature <-400°F
Max. Continuous Op. Temp. 500°F

It's also almost totally inert and resistant to all industrial solvents.

I don't think the bottom 2 inches inside the reflector would break 500 degrees. Will it?

Hi Thomas

Don't use silicone tubing. It doesn't like liquid butane or propane.

Go for 1/8" Tygon PTFE or PFA tubing. There are equivalents as well, from Cole Palmer etc. Jacket in fine SS braid.

Design so the tubing does not get that hot – and watch out for the O-rings too.

Caution: the tube will get warm: make sure it can't blow outwards and leak at the junctions.

Cheers

Any particular reason to use a SS braid PTFE instead of a plain PTFE hose?

> Any particular reason to use a SS braid PTFE instead of a plain PTFE hose?

Ah – slight misunderstanding here. You can't buy PTFE tubing in 1/8" size with SS braid over it (afaik). The smallest you can buy is 1/4". That size is routinely available for fuel injection on cars, but it is very heavy and stiff. It has been used by several stove vendors, but many people have commented that the result makes the stove wiggle around at the end of the hose.

What I was suggesting is that you get the 1/8" PTFE (or FEP or PFA) tubing and sheathe it with some SS braid. I had to buy the SS braid from China, custom made, but you might be able to find something in the USA.

WHY use it? Two reasons, and underlying both of them is the danger from a gas leak. You haven't lived until you have experienced one: extremely dangerous. Paranoia is excellent.

The first reason is to avoid any cuts and other damage. All three plastics are tough in tubing form, but accidents can happen. Note that even PTFE is not immune to melting on a bit of red-hot stove.

The second reason is that having SS braid over the tubing and crimped onto the connections at each end gives a degree of security against the connection failing. The tubing is held in place.

Cheers
Roger