As promised....
After weighing it and calculating with the amounts boiled so far.....
Coleman 100 gr butane/propane canister when full weighs 190 gr, empty it is 90, or at least the other 3, now empty, ones were.
After this weekend it comes in at 160 gram and a total of 6 half liters brought to a boil.
190 - 160 = 30 grams -> 30/6 = 5 gram per half a liter (pint-ish) of boiling water
100 grams of usable gas means 20 times half a liter, means 10 liters, not the stated 12.....
But the average figure when completely tested with this gas canister might change. Optimal conditions, water temp, wind etc are all a factor here. Not complaining, just measuring....
If I go for boil in the bag meals and 1 cup of coffee that equals (about) half a liter, which is not always the case, e.g. a cold breakfast or lunch....., it should last me long enough for most of my purposes....
O yeah and a friend of mine did use his Jetboil on an open fire, as a 'test for survival circumstances' and it went through unscathed.....
Grtz Johan