10 November 2005

Cartridge Versus Liquid Fuel Stoves

Cartridge Versus Liquid Fuel Stoves

Cartridge Versus Liquid Fuel Stoves image

If we ignore other stove types such as the Trangia, which runs on methylated spirits, and weird stoves that run on gel, Hexamine and rabbit droppings, stoves can be split into two types. Cartridge stoves run on a removable, self contained gas cylinder such as Epi-Gas, Coleman butane/propane and MSR IsoPro, were the liquid gas is held under pressure and is released as in gas form into the stove. Liquid fuel stoves burn use conventional combustible fuels like paraffin, petrol and white gas, with the fuel being pressurised once the stoves fuel tank has been filled. Both stoves have their strong and week points, and this article is designed to help the user decide what system will work best for them.

FOR

Cartridge stoves light instantly and give a full power flame from the word go. They pack up small, weight nothing and hide away in you pan set until needed. They are cheap and simple and the gas can be found in any camping shop. The gas cartridges don’t leak and unscrew with no hassle for packing, plus once used they weight nothing, and once stamped flat take no room in your pack. It is also safer to use in confined cooking spots, both due to lower CO poisoning risk and a more predicable flame (no priming flare up).

Liquid Gas stoves are tough and dependable once mastered. They produce a consistent heat output in any conditions, pumping out a constant flame that will not decrease as the fuel source empties. Although complex they can be repaired in the field and many burn anything from the go juice in your car to dry cleaning fluid.

AGAINST

Cartridge stoves and the gas they use are too easily effected by cold and altitude. The canisters can become damaged, or be faulty, either through manufacture or through tampering, meaning you can never be confident in your fuel supply. If the stove breaks you can’t mend it. The heat output drops of as the cartridge looses pressure and can be painfully slow in bad weather.

Liquid Gas stoves are heavy, bulky and over complex. They can be dangerous due to flare ups or fuel leeks and spills. They are dirty and a pain to prime. They require patience and skill to use safely and effectively. They can be poisonous in confined spaces.

THE EVIDENCE

PRICE

Liquid gas stoves are considerably more expensive then cartridge models, with some being over 400% dearer! The higher cost is due to the increased complexity of design and construction. This also translates into a longer life span - with parts back on most brands meaning you can repair and upgrade the model as time goes buy. Cartridge stoves are simply an open and close nozzle, not that dissimilar to a blow torch fitted with a pan supports, and are with a few exceptions are very simple and low tech. Spare parts are almost unheard of so when it stops working you simply buy another one.

FUEL AVAILABILITY

Resealable gas cartridges as always available in any western camping store, and most fit all stoves. Once off the beaten track you may still be able to find gas but it is often of a more exotic verity - like gas canisters for paint strippers and blow torches. Having a stove with a universal attachment is crucial if your going of the beaten track, and even then don’t count on warm dinners. The blue Bluet non resealable gas cartridges are very common all over the world but are limited to the specific Bluet stove and are of limited value for anything other then the most pedestrian camping, both due to the type of gas used and the design , i.e. once attached it must remain on the stove until empty. Go Gas make an adapter so you can convert Bluet cartridges to fit a standard resealable cartridge stove - which also allows you to remove it for packing. For fuel availability, the liquid stoves win the battle hands down, especially the high quality multi fuel units. Paraffin/Kerosene and petrol can be found wherever you can find people, and White gas can also be found just about anywhere with a bit of searching (find out what it’s called first in your country of destination). If the fuel does not come packaged for stoves then it’s worth filtering it before you run it through your stove as there may be particle matter in the fuel that may block you stove. Some stoves like the MSR XGK-II seem to burn just about anything and I even met one guy who clamed he’d used pig fat! If your stuck without the correct fuel, or are forced to use dirty fuel (unleaded petrol, contaminated fuel) then try running the stove anyway but clean it as soon as it’s cooled down. Some stoves designed to only use White gas may work on other fuel types - JUST BE CAREFUL AND CLEAN THE STOVE AS SOON AS YOU CAN.

The new hybrid stoves that will take both cartridges and liquid may be worth considering, but personally I prefer dedicated models and so far the models on the market don’t compete with either the best cartridge or liquid gas models, and in my eyes are just a middle of the road compromise.

EFFICIENCY

With a full cartridge of gas, sitting on your kitchen table at sea level, a cartridge stove is faster then the best liquid stove, especially if you were to take into account the amount of time it takes to prime the liquid stove. Unfortunately in the field this does not seem to be born out. Once the weather gets nasty, or when the canister is half full, then the liquid gas wins out - due to it having the same efficiency throughout the life span of it’s fuel supply. The major difference accurse when it gets cold, with the Cartridge stoves loosing performance rapidly as the temperature drops, up to the point were it ceases to work all together.

RELIABILITY

A good quality Cartridge stove using quality cartridges should keep working for many years. A pricker (always carry two) is the only tool needed for maintenance, and care must be taken that it is always clean and dry when stored. Unfortunately when it stops working it stops working for good. If your camping in the Lakes this is just annoying, if your half way up some major Alpine face in winter, as has happened both to me and three other people I know, it can be extremely traumatic. Because of their low weight some climbers may chose to take two burners, which is ok as long as you don’t find your canisters are the problem. Several climbers have had trouble in the former Soviet Union, Nepal and India, with faulty gas. The cause seems to be people refilling half used canisters with water instead of gas. The gas floats on top of the water, and works until there is only water left. A good quality Liquid gas stove is highly field maintainable, with spare parts and maintenance kits available for those venturing far from home. By getting to know your stove you can build a great deal of confidence in it’s performance. It’s well worth practice stripping down the stove to see how it fits together and more importantly how it works. Like a soldier with his rifle, your stove is your best friend, and like a soldier you should look after it if you want it to look after you.

WEIGHT & BULK

If you want a light weight stove then cartridge stoves win. Stoves like MSR’s Pocket rocket (86g), Coleman Micro (146g) and the Primus Alpine Micro ( 116g) weight less then a couple of carabiners, yet burn hot and efficiently. The other bonus with the micro burners is they are tiny, fitting into a large match box, meaning you can pack them away in a minimalist pan set along with some compact food, lighter, spoon etc, a boon if your taking one along for unplanned stops, or when you need to pack everything away in a small rucksack if your moving fast - running, or climbing. Take a few minutes to see how you stove fits together as most systems can be dismantled, both to aid packing and to allow you to retro fit them to hanging stoves or remove unwanted windshields etc. Liquid gas stoves on the other hand are on average twice as heavy and three times as bulky. The comparative weight of liquid versus gas is actually pretty much he same. The two main differences are that cartridges a far bulkier and must be packed in and out.

ENVIRONMENTAL FACTORS

ALTITUDE

The higher you go the lower the atmospheric pressure. This will effect your stove. With a cartridge stove, which is basically a gas held under pressure, the drop of pressure will cause the gas to bleed out more forcibly. Firstly this has the advantage that you will get a slightly better burn time (if you remove any other negative variables like temperature) and the canister will show a slight increase in performance through it’s life span. On the negative side you can experience ‘blow out’, where the flame is either impossible to ignite, ignites incompletely, or just goes out mid burn for no apparent reason. This is caused by either too much pressure or a lack of oxygen. Blow outs are both frustrating and dangerous. The lack of a flame means that gas is leaking into your atmosphere - which is both toxic and potentially explosive if it is not stopped quickly. On a committing climb you are also faced with the nightmare scenario of loosing large amounts of your fuel, which in the long term means a loss of food and more importantly water if snow has to be melted. As the pressure inside the cartridge drops then blow out should cease - unfortunately by then you’ll have lost gas. Partial ignition or ‘blow out’ may also be caused by a lack of oxygen getting to the flame (a common problem with hanging stoves that feature ventilation holes more suited to sea level use). This is solved by improving ventilation to the flame and increasing the combustion area - the distance between the flame and the pan. This should only be a problem with hanging stoves and usually requires the lifting of the pan supports or drilling more ventilation holes.

With a liquid fuel stove the lower pressure will also result in ‘blow outs’, but this is more easily solved by lowering the pressure in the fuel bottle by reducing the number of pumps when pressurising.

COLD

The cold is the killer of Cartridge stoves. Butane won’t work below -1C and mixtures (Iso-Butane & Butane-Propane) produce weaker and weaker flames as the temperature drops. Also, the cartridge becomes colder and colder itself as the fuel leaves it, compounding the gases inherently poor cold performance. The only way to combat this is the keep the cartridge warm. This can be done in several ways, some safe, some not so safe. The old favourite was the heat exchanger method, were a piece of flat copper went from the flame to the canister. The problem with this, apart from the bleeding obvious, was it directed heat to a very small area, and although effective, was both dangerous and hit and miss. The main drawback though is that the canister can get so hot - you could hear the gas boiling - that the rubber seal in the canister could deform, causing the canister to loose all it’s gas when unscrewed. A better system is to dip the cartridge into the pan of water your warming, every few minutes. The water only needs to be above freezing to be effective, and once dunked, the stove will fire on all cylinders for several minutes. This has the bonus of being simple, pretty safe and requires no modifications. Some people recommend shaking gas cartridges that contain a cold weather mix, as the gas that performs better in the cold burns off faster, and mix separates. Whether this is true or not I can’t say. Other ways to improve performance is to use a windshield which will trap heat around the canister, heat pads, either disposable or re-usable, which can be applied to the base of the cartridge or simply holding the canister in your hands.

Good quality liquid burning stoves are not effected by the cold until the temperature drops below -20C - at which point impurities may develop in the fuel, clogging the stove. Therefore anyone venturing into really cold conditions must use a stove that is clog resistant and easy to clean and maintain. Saying that you’d be hard pressed to be cooking in that temperature while in tent, plus once the stove is lit the temperature will soon rise. Paraffin is not recommended for cold use as it leaves an oily deposit in the fuel line, and requires careful priming, a real chore in the cold. Again, remember that when judging what stove to use, that cooking inside a tent or snow hole will make an enormous effect on the ambient temperature.

THE VERDICT

So what’s the best stove to buy? As usual there is no answer - only more questions. The only real option is to have both types of stove and use whatever best suits your trip. Cartridge stoves are most efficient for use at low to medium altitude, in hot to moderate (0C) temperatures in for minimal use (not expedition cooking). Liquid Gas stoves are idealy suited for long term use in any conditions and at any altitude. Below is a brief user profile of what stove I think best suits the most common situations.

LIQUID GAS USER TYPE: Expedition. Alpine/Snow & glacial. Exploration. Trekking. Winter or long distance backing.

CARTRIDGE STOVE: Alpine/Rock & fast and light. Competition. Emergency. Short backpacking trips. Big Wall.

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