Monday, February 4, 2008
Survival gear: The indespensable backpacking stove
I've always liked backpacking stoves.For me, they're basic equipment. Although I have and use larger, two (or more) burner camp stoves, I can make due with a good single-burner backpacking stove, and because of its compact size, it's more likely to be at hand when I need it.
Backpacking stoves are different things to different people. Most backpackers either use some kind of fuel cannister stove, or a super lightweight stove that burns alcohol (liquid or gelled) or fuel tablets. The super lightweights have their place, and were I embarking upon a long-distance trek I would probably use something like that. Also, such stoves, especially the tablet type, make good emergency survival stoves for a fanny pack or similar that is loaded with items intended to keep you alive for one or two days if, say, you are stuck in your vehicle during a blizzard.
I've used both tablet stoves and homebuilt alcohol stoves in the past, and they work fine for their intended purpose.
Butane cannister stoves I have no use for. They don't work in extremely cold weather, the cannisters are expensive and bulky, and you still have to pack the cannisters out and dispose of them when they are empty. On the other hand, they are convenient and both the stoves and their cannisters store well without degradation over time, so they may meet some people's needs perfectly.
Propane stoves are another matter. They are similar in design to the butane stoves, but they use cheap, standard 1 lb propane bottles that are available everywhere and used for a variety of different portable appliances. They are also refillable, with the proper adapter, from a standard 20 lb bulk tank; which makes them even cheaper. Just be aware that it's illegal to transport them after they've been refilled. I use refilled ones at base camp, and only transport new ones and empty ones. I also discard any that begin leaking through the valve, or show any signs of rust.
For a bug-out stove, a stove for living out of a rucksack for extended periods, or one to keep in the truck, the best are the pressurized, liquid fuel stoves. They are the most robust of the backpack stoves, and work on the same principle as the larger multi-burner camp stoves. The best of these can be used on a three-times-daily basis for years, with only minimal maintenance.
There are two broad classifications of this type of stove; those which must have air pumped into the tank for pressurization, and those which build pressure naturally as the fuel in the tank warms.
The various Coleman single-burner stoves are all of the first type, with a built-in air pump for pressurization and a replaceable "generator"; a tube which, through a combination of pressure drop across an orifice and absorbed heat (the tube passes through the flame), vaporizes the fuel before it reaches the burner. This is also how the larger two-burner Coleman camp stoves operate. It makes for clean, efficient burning and a flame that can be adjusted from a low simmer to hot enough to boil a quart of water in 3 minutes. The downside is the fuel must be top quality and absolutely clean. Even those stoves that are advertised to work on unleaded automotive gasoline, work much better on "white gas" camp fuel (Coleman fuel, etc.). Also, there are lots of parts that must be maintained in top condition, such as the pump, valve, all fittings, and the generator. The generator is replaceable, and will have to be replaced periodically. The pump, if not maintained, will eventually fail to operate; and no pump, no flame. The valve and fittings can get out of adjustment, causing leaks which flare up and can turn the stove into a bomb.
This is not as bad as it sounds, especially if the stove is being used regularly, because one just keeps a spare parts kit and deals with any minor issues as they present themselves. After all, the US military has been using these stoves since the start of WWII, and a nearly identical stove is still sold by Coleman. I have one I have been abusing since the 1980s, even using it to melt lead for bullet casting, and it is still kicking. They are cheap, too. The last time I checked, a new one could still be had for under $50; and I have seen used ones go for under $10 on Ebay.
One style I don't recommend for a primary stove, although they are popular, are the ones that use a separate fuel bottle, connected to the stove by a hose. They have several good things going for them, and a couple of bad things. The main problem with them is that hose, and its connections. The hose and its two connections get flexed every time the stove is used, and both connections get dis- and re-connected repeatedly. Eventually there is going to be a leak of pressurized fuel; it is inevitable. Worst-case, one of the connections can become completely disconnected and roll around, spewing burning fuel everywhere; or just explode outright. Do you want this happening in your tent, cabin or vehicle? I didn't think so.
I do have one. I loved it when I first got it. Then I used it daily for a few months, and it did eventually start leaking.
The second type of pressure stove builds pressure naturally, without pumping, using the principle of thermodynamics. Here's the way it works: You take the stove out of your pack. If it's already full of fuel, you just crack the filler cap to equalize pressure, then retighten it. If it's empty, of course you're gonna have to open it anyway to add fuel, so pressure equalization occurs naturally. Either way, make sure the cap is tight so it doesn't leak, then hold the tank in your hands for a minute. Maybe breathe on it a little, too. You are trying to raise its temperature a little, relative to ambient temperature. This will slightly pressurize the tank. After a minute or so, slightly crack the valve, watching for liquid fuel to flow into the burner. Once you see that fuel, light it. After it burns a minute or so, slowly begin opening the valve further. The hotter it burns, the more you can open the valve, feeding it more fuel until it is at a full roar.
You can start it faster by drawing a little fuel from the tank with the included medicine dropper, and squirting it into the burner to prime it. Some people actually fill the stove, deliberately spilling fuel all over the works, and just throw a match on it (outdoors on bare earth, of course, and with the cap tightly closed and the valve open) so it flares up, and by the time the flames recede it is well warmed and ready to cook. Very dramatic, and gets the job done. Also quite unnecessary, in my opinion. The point is, anyone with any imagination at all can get one of these operating, in any kind of weather, and even if the dropper has been lost.
They are also very reliable. Sure, they may require a bit of fiddling on occasion, but they have no generator and no pump... although some of them have an optional, detachable pump to absolutely eliminate the preheating phase as well as producing 50% more heat output than without the pump; but this pump is in no way necessary to the operation of the stove.
This style of stove has been produced all over the world for well over 100 years, and they have been made to burn kerosene, gasoline (both white and automotive), diesel fuel, and alcohol. Actually, I doubt there is any liquid fuel they can't be made to burn. Germany has produced many of them, as has Russia, China and many other countries; but probably the most popular and well known are those produced in Sweden. In fact, the design originated in Sweden in 1892; the inventor was Frans Wilhelm Lindqvist.
My personal favorite of all backpacking stoves is the Optimus 8R Hunter; it is of this design but, unlike most others, is contained within a steel box which not only holds everything within a small space, but also protects it from damage.
With an 8R and a bottle of fuel in your bugout bag or in your truck, you are always ready to cook something, make a hot drink, or make some water safe for drinking. In fact, if you are in your truck or jeep, or on a motorcycle, ATV, boat or whatever, you can always siphon some of the fuel from the vehicle to use in the stove, if necessary.
More about the 8R
Here is a review I found at Epinions.com:
A Swedish Workhorse, Well, a Pony
Jan 09 '04 (Updated Aug 09 '04)
Author's Product Rating
Product Rating: 4.0
Utterly reliable; almost maintenance free, no plastic to melt or wear out; minimum moving parts.
A smaller fuel tank, heavier overall weight, less heat output than modern canister stoves.
The Bottom Line
Though older in design and age, hardly anything in its class--even more advanced models in the market--will beat 8R for its utter reliability and simplicity.
Optimus 8R is a time-proven stove. Along with M99 (with aluminium housing) that is a variation of 8R and 123 that share the same burner, 8R deserves the respect of the user who understands its working.
The usual complaints directed towards 8R are: 1) takes too long to boil a liter/quart of water; 2) does not produce a strong flame; 3) too heavy; 4) fuel tank too small, etc.
In the first place, 8R is designed to meet the needs of a single hiker. A single hiker rarely needs to boil a quart for himself--perhaps a pint at most. With the mini or midi pump, the stove puts out more than sufficient heat to boil a pint in less than 4 min. That is just enough for one person. The fuel tank will last about 45 min. at full blast. With a small MSR fuel bottle (11 oz.) and a full tank of gas, you have about 3 hours of total burning time at your disposal. That is almost 4 days' worth of fuel for one person in a warm season. A tankful of gas (4 oz.) will last for a day.
(UPDATE) A large BTU stove is useful, if you need to melt snow quickly, or boil a soupy meal that involves boiling a quantity of water. For regular cooking, such as frying hamburger patties, making omelettes and overeasies, or boiling rice, lower heat setting is required. Let me assure you: 8R (and 123) has a plenty of firepower to burn your food. You may even need the heat diffuser, in order to get your food done correctly. This is so, especially if you are using thin pots and pans. In order to assure the ability to control flame output, do stick with white gas only. If you use automobile gasoline, its higher octane makes 8R and 123 an on-off stove, not to mention the toxic fumes from the additives. It would be impossible to have a range of control for the flame output that is necessary to simmer (8/9/04).
Compared to the modern canister stoves, 8R surely is heavy, but throw in a canister or two, and weigh the whole setup, and there won't be too much difference. Those who carry 8R carry it not just because it is small, but it also gives a certain degree of emotional satisfaction besides its proven reliability.
While regular fuel canisters will have difficulty going in a very cold weather or at a high altitude, the humble 8R will perform with indifference. In order to make sure that your first 8R live up to its reputation, the user needs to understand the following points.
8R operates on self-pressurization generated by the burner heat. In order to get the maximum performance out of it, 1) make sure the fuel cap has supple and smooth seals (one large, one small). If the seals are not at optimum condition, your stove will lose the air pressure, and not put out a strong flame. Either replace the cap or make your own seals. Or, go to a hardware store's plumbing section, and get a few 3/4 inch outside diameter rubber washers. They can be also found in the individual bins section, as well. Some rubber items are susceptible to fuel, but get a few, and replace it as needed. They are lot cheaper than buying the new cap.
2) before each time you start 8R (123 or 99, or any stove operating on self-pressurization, for that matter), open the fuel cap to introduce air, so the fuel tank will have enough air to build up the pressure.
3) If the stove is exposed to the cold, windy weather, be aware that the cold wind does rob the heat from the fuel tank. The lowered temperature of the fuel tank would lower the internal pressure, and the size of the flame would diminish. This happens, when it operates without the help of the pump. This would not happen to Svea 123, because its burner sits right on top of the fuel tank, and the brass windshield, in full contact with the fuel tank, supplies the heat conduction from the burner directly to the fuel tank. 8R's fuel tank sits sideways to the burner, in comparison, connected by the fuel tube. It receives relatively less heat from the burner than Svea 123's fuel tank does. Just turn the stove, until you find the happy medium between the burner heat and cold wind that keeps the fuel tank hot. Or, remove the heat shield for added exposure to the burner heat.
4) For pre-owned 8Rs and 123s, often there is whitish deposit within the fuel tank and around the wick, and carbon deposit in the fuel passage that leads to the burner and burner stem. These serve as obstructions, and they need to be cleaned out. The most painless way to clean the brass is to put it in a plastic tub of household vinegar. It losens all carbon deposit and tarnish. Immerse the whole brass assembly for a few hours, and rinse with water and clean with a plastic brush. Then you might want to apply Brasso for the warm shine of the brass. Once you do this, you will be hooked to the stoves made with brass.
You've been forewarned.
5) Remove the fuel tank from the cradle, and remove the burner assembly from the fuel tank, along with the wick. Fill it 1/2 full with fuel, cap it, cover the hole left by now removed burner assembly with the thumb, and shake it vigorously. Drain out the fuel into a cup and see if there is any debris. Using a clean, filtered funnel, refill, shake, and drain. Repeat the process, until you see nothing in the cup. If you are at this point of disassembly, why not clean the inside of the fuel tank as well? Put the fuel tank in the tub of vinegar for a few hours. Let it fill completely with vinegar and let vinegar clean the inside of the fuel tank. A clean fuel tank produces pure blue flames, and clean fuel keeps the stove running unclogged. Reassemble the parts after you are sure the tank is devoid of any debris or water.
6) The wick's condition is critical to the operation of the stove, as with the fuel cap. Inspect, soak, and wash it in the fuel or mineral spirit. If badly worn, replace it with a new original, or fashion yourself a new one with cotton twine and wire. Just copy the format of the original. Soak the wick with fuel, and insert the head as far as it will go. A wet wick enters the tube easier than the dry one. Don't make it too thick, so it has trouble entering the tube. If you force it in, overly tight wick will interfere with the fuel flow. It will also overpressurize the fuel tank, and blow the gasket later. Make sure the inside the tube where the the wick is inserted is clean and shiny.
If you make it too thin, so that the wick slides in and out too easily, the air within the fuel tank will leak out through the air pockets within the wick strands, and the fuel tank will never develop the pressure. If you did not know this, you would think the stove is defective. Make the wick nice and tight, so that air stays in the tank and do the job of pressurizing the fuel, so that only the fuel travels through the fuel line.
If you want to make sure your home-made wick is not leaking air, follow the procedure below; you will need the Optimus' proprietary midi or mini pump: a)fill the fuel tank below the wick level, b) put the pump cap on, c) pump up with midi pump, e) open the valve. If the air leaks, you will hear intermittent bubbling sound from the jet. You will also see the air bubble coming out with fuel.
7) The spindle is tightened by a "stuffing box." It is the 10mm nut that keeps the spindle fixed to the burner control. Inside is the metal and graphite packing that keep the vaporized gas from leaking out. If it leaks, it will show the tiny flame. Tighten the nut a little with a wrench. If the nut is bottomed out, it needs a new graphite packing. The graphite packing comes within the maintenance kit that costs at least $10 plus shipping and handling. There is an alternative remedy to this. Check out the plumbing section at a hardware store, and get a packet of graphite packing. They come in two types: thin spaghetti shape and thicker rope form. The two together cost less than half the price of one maintenance kit. Get both kinds, and they will last almost a lifetime. These will also work for Optimus 111, 123, 99, and other stoves that require the heat resistant seal. After all, a stove is basically a system of hot gas plumbing, right?
8) Sometimes the previous owners tamper with the cleaning needle and do not put it in correctly in relation to the spindle. If this is the case, you will not be able to shut off the stove, once you started it. Do not close the lid on the burner in panic: it will only ruin the paint job. Do not fling it away, for it will only put a dent on the case. Pour a pot full of water over the burner, instead, and when the flame is out, quickly open the fuel cap. It will depressurize, and the fuel will not come out of the jet. All you need to do is to wipe it dry and reset the spindle and the cleaning needle.
Here is how: a) remove the burner; b) remove the jet, using the key provided; c) loosen the spindle nut (takes 10mm wrench); d) turn the spindle counterclockwise--you will see the needle rise out of the hole; e) remove the needle and turn the spindle clockwise as far as it will go; drop in the needle with its gear teeth facing the fuel tank; f) while adding a gentle pressure on the needle with a finger, slowly turn the spindle counterclockwise and count 4 teeth slipping the gear; then turn the spindle all the way clockwise; g) reinstall the jet, the burner, and tighten the nut: now the stove is ready to go.
If you want to speed up your 8R to reach the top performance pressure, remove the heat shield temporarily. That exposes the fuel tank to the greater heat absorption. Once the flame is well established, reinstall the heat shield, in order to avoid overheating.
In cold weather, in order to speed up the pressurization, squirt not more than 1/2 medicine dropper full of alcohol (use ONLY alcohol, nothing else!) at the bottom of the fuel tank on the side of the burner. Make sure the spindle is shut tightly. Then prime the burner as usual. This will heat and pressurize the tank. Then open up the spindle halfway (which is max. throttle) and observe the satisfying blue flame roar into life.
All this can be eliminated if you invest in a mini or midi pump. It is worth buying, though overpriced. As a matter of fact, I would recommend a pump for all 8R users. Just attach the pump to the post on the fuel cap, pump a few times, prime it with either alcohol or with white gas from the fuel tank (make sure to tighten back the fuel cap). Just before the flame dies down, open the spindle: Roar! Pump a few more times as needed (Because of this need for an extra item for a bigger flame, 8R gets only 4 stars in the overall rating). As with any other stoves, a wind shield is always a good thing to have.
If carrying extra bulk of windshield is too much, one may cut out a strip of aluminium flashing, 1 1/4 in. wide and 13 in. long. Bend it along the perimeter of the lower shell, opposite the fuel tank. Cut out a tiny slot for the key chain. It will now serve as a windblock a la mode of Enders 9061 stove. Only make sure the wind does not blow the flame over the fuel tank, and do not use it when it is not windy. The tank will overheat.
Another useful modification is to get a length of fiberglass rope gasket for the woodstove door and make wicks for priming. First measure the proper length, and tie the ends of the rope with metal wire, so that it will not unravel, when cut. Make two of about 2 1/2 in. Put one in the priming cup and bend it in a circle; put the other one under the fuel tank between it and the burner. Whenever you prime the stove, squirt 1/2 medicine dropper full of alcohol (use ONLY alcohol!) into the wick under the tank, and one full dropper full into the doughnut of the wick in the cup. The wick under the tank will enhance the priming action by heating the fuel and air quickly in a cold weather--alcohol burns longer with a wick. The stove reaches the full pressure almost immediately, and puts out the full flame.
I have equipped all of my 8Rs, 123s, and 111s with these modifications, by the way. Once you have tuned or modified it this way, 8R requires very little maintenance. 8R will serve you reliably, as long as you know its character.
The new 8R performs as well as the older ones, but if I may, I would recommend that you get the older 8Rs. Ebay seems to be the best source, besides your local garage sale. They were made better than the new ones sold by Brunton. As the inflation shaved the profit, Optimus had to simplify the process, and a few corners were cut. The older ones have more aesthetic appeal with better quality components. But I must add that the new ones' performance has not diminished in any sense. You decide.
Whutcha waitin' fur? Get out thar!