In a perfect world, all backpacking stoves could use Coleman’s PowerMax fuel canisters (cartridges). These aluminum canisters have the best ratio of canister weight to fuel. Compare, for example, MSR’s IsoPro fuel in the 113 gram size, where the metal canister equals 50.0% of the full canister gross weight, versus Coleman’s PowerMax 300 canister (which allegdely contains 11.1 ounces of fuel), where the metal canister equals only 19.9% of the full canister gross weight. There is also PowerMax 170, which contains 6.0 ounces of fuel, and has a corresponding ratio of 26.8%. PowerMax canisters contain 60% butane and 40% propane in liquefied form, and have a tube inside which extends towards the bottom for drawing out the mixture in liquid form. PowerMax is intended to work only with Coleman’s Xtreme, Xpert and 2 burner Xpedition stoves. These stoves incorporate proprietary hardware which changes the liquefied gas to a gaseous vapor for combustion. Compared to most stoves which use ordinary butane/propane canisters, the PowerMax design allows the stove to perform in subfreezing weather without a performance degradation due to the drop in vapor pressure inside the canister.
Can PowerMax canisters be used with ordinary canister stoves? An intriguing bit of information at the Zen Stoves Website at http://zenstoves.net/Canister.htm#CanisterAdapters hints that this may be possible. “Markill [now Vaude] makes an adapter for the Campingaz CV line that may also work with the PowerMax canisters. Just beware that if you use the PowerMax canister, fuel will come out in liquid form, which may be dangerous depending on your stove.” Vaude’s “Adapter für Ventilkartuschen,” weighs 75 gram (2.6 ounces) and was (and may still be ) known as model number 92497. It also allows CampinGaz CV 270 and CV 470 cartridges to work with any stove which uses the EN 417 Type 2 standard cartridges.
There are several issues here, though. The first is whether the adapter can safely attach in a leak-proof way onto the PowerMax. The second is whether it will work with any stove which has a pre-heating tube or functional equivalent. The pre-heating tube is a metal tube in which the pressurized liquid fuel flows inside. The tube is arranged to go through the stove’s flame, so the heat changes the fuel flowing inside from a liquid state to a vapor state. At least two non-PowerMax stoves with pre-heating tubes have been successfully converted for use with the PowerMax cartridges:
MSR Wind Pro stove modified to use Coleman Powermax fuel cartridges
http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=1756&disable_pagination=1
MSR Rapid Fire stove modified to use Coleman Powermax fuel cartridges
http://www.backpackinglight.com/cgi-bin/backpackinglight/xdpy/forum_thread/1702/index.html
Could PowerMax canisters be used with Coleman’s new Fyrestorm stove, which uses ordinary, but inverted butane//canisters so that the fuel is drawn out in liquid form? Bill Fornshell, I believe, seemed to think this could be done, but only if the hardware from a PowerMax stove which used to change the fuel from a liquid to a vapor were added. Could the Markill adapter also be used with a Primus OmniFuel to burn PowerMax fuel? I am not sure if the OmniFuel has a conventional pre-heating tube arrangement, but it has the functional equivalent.
And finally, what about the danger of lighting the stove? Presumably, when the fuel first comes out of the jet, it is in liquid form, because it has not yet been heated to a vapor in pre-heating tube. Is this problem overcome by simply being very conservative about opening the valve? How did the modification of the Rapid Fire and the Wind Pro handle this problem?
In view of the fact that Coleman has said PowerMax fuel will continue to be sold notwithstanding rumors of its demise, and the fact that the empties can be easily punctured with a tool and recycled, this fuel offers backpackers an advantage in weight and performance and safety (compared to gasoline stoves) which is unmatched.
