Has anyone any experience of these?
http://www.primus.eu/Templates/Pages/3_cols_white_middle.aspx?SectionId=5888
Any idea where to buy in the UK, and
will it fit the small refillable gas canisters that are available.
You haven't said which cannisters, nor which gas. You will probably want butane, but some burners will burn several different fuels including different gases. Different gases come in different bottles. There are many different sizes and types of thread, it's a bit of a minefield, but there are also many adaptors available so you'll probably manage somehow. Some gas cylinder styles have appeared on the market for a time and then disappeared, if you've owned a gas blowlamp you'll probably know about that already. Best to find a supplier of the cannisters that you think you'll be using and ask them what they think of the particular one you plan to use. Some varieties have been around for decades and will likely be around for decades more. I have a double burner gas stove that's well over 40 years old, it takes 907 style cylinders (2.75kg of gas) which you can still buy in most parts of Europe, and it also fits a nice compact single burner that I have, very much like the one you linked to -- although I don't know if the one you linked to will fit it. If the supplier says it will fit a 907 you're home and dry.
I don't really know much about refillable gas canisters, but given the price of parafin/aspen or small gas canisters, this looks like a good, uncomplicated, everyday camping solution.
Generally speaking gas will be a bit more expensive than paraffin for the same amount of heat, but unless you're camping for many months the cost of gas cooking won't be an issue. If you're using it for heating or for boiling large quantities of water (for a troop, or for a few hot water bottles) then the cost might start to make itself noticed. There's a good comparison
here but bear in mind that you pay a lot more for gas in small containers than in the sort of volumes that they use for home heating so treat the figures with caution.
At low temperatures, some gases burn better than others. Butane is notorious at freezing temperatures, because pure butane boils at just under the freezing point of water. So if it's frosty, your butane will stay in the bottle as a liquid instead of coming out of the bottle as a gas. When a liquified gas boils (as it must, to get out of the bottle) it cools the remaining liquid gas. The faster you use the gas the more it cools the liquid in the bottle. That means that even at temperatures which are warmer than the boiling point of the gas, using the gas quickly might cause the liquid in the bottle to sool so much that it behaves as if the ambient temperature is colder than it really is. You will sometimes see frost form on the outside of the bottle, from the bottom of the bottle to the level of the liquid in it.
Propane and mixtures of propane and butane are better at low temperatures because propane boils at a much lower temperature than butane.
The regulator, piping and gas burner need to be designed to work with the gas or gas mixture that you're using or they could be dangerous.
