MCBushbaby
03-24-2008, 11:20 AM
Due to the recent interest in alcohol stoves in the Wax Stove thread, I think a devoted thread is warranted. These are easy DIY stove designs that are lightweight, cheap, and easy. There are many versions, each with certain 'features', but the basic setup and designs are shown below along with pros and cons. All alcohol stoves share one features: all require the fuel to vaporize and ignite for a sufficient burn (burning liquid alcohol doesn't burn very long or very hot).
Open Flame Alcohol Stove
http://zenstoves.net/Basics/OpenFlame.jpg
Basically a dish of some kind, filled with alcohol, and lit on fire. Too simple, too open, not enough heat, horrible fuel efficiency, don't build. Period. Sorry.
Open Top Jet Alcohol Stove
http://zenstoves.net/TopBurner/TopBurner.jpg
These stoves are probably the most common because they're the easiest to make and take very little skill in assembly. Simply fill with fuel, light the inner chamber, and wait for the fuel to vaporize. The steps for assembly can be found here (http://zenstoves.net/ConstructionStep2-FuelPort.htm#Step2aOpenJetStove). The cons of this design are threefold: one, it takes multitudes longer to prime the alcohol to vaporization, you are burning your interior stove fuel for priming, and the fuel burns freely so there is less fuel efficiency. If tipped, the stove could spill lit fuel.
Pressurized Jet Alcohol Stove
http://zenstoves.net/Construction/polished.jpg
These stoves follow a similar construction pattern as the open top, but there is no cut-out section. Rather, a small hole is drilled into the bottom of one pop can as a fuel port. The port is then covered with an object to prevent a flame from entering the body (if a flame hit the vaporized fuel within the body, it could explode). The priming takes much less time (<30 sec) and the jets are higher pressure, giving better fuel economy because the alcohol is vaporizing better. Instructions can be found here (http://zenstoves.net/ConstructionStep2-FuelPort.htm#Step2bPressurizedJetStove).
Cons are that you need more dexterity in assembly as well as noting the potential for an alcohol bomb if you don't replace the fuel port cover (I use a simple metal bolt). You also will need to carry around a small dish (or lid off a soup can) for priming the stove.
Comparisons
These are the three main designs - each having many subdesigns. The open-top jet has given way to many lightweight alternatives and "simmer rings." Because of it's low-pressure output and open inner camber, covering some (or all) of the jets won't snuff the stove and will produce a simmering effect on your cooking. The pressurized jet are the favorites of backpackers because of it's fuel efficiency (compared to the open top) and it won't spill fuel or cause a fire hazard if tipped. They also burn much hotter for longer periods because of the torch-like jets they produce. My titanium pot handle turned red-hot when a jet was under it, reflected by my aluminum foil windscreen!
Fuel
Pop can stoves burn Isopropyl, Methanol, Ethanol, Everclear, and Denatured Alcohol. The cleaner the alcohol, the bluer, hotter, and less sooty the flame. Isopropyl, in concentrations exceeding 80%, burn just as well as Methanol HEET (95% Methanol). Denatured Alcohol burns hottest, if I remember correctly, and Everclear is "drinkable" so it's taxed by liquor laws making it more expensive than the other options. The better the stove is at vaporizing the fuel and forcing it out the jets, the easier the fuel will mix with air and increase heat output and length of burn.
Potential Issues
*Overpriming and constriction of heat within a reflective windscreen may overheat the alcohol of pressurized stoves, causing a rapid expansion and eventual seam burst. However this has not happened to me and I've damn near taken a blowtorch to it.
*Pressurized stoves may explode if the fuel cap is left off and a flame enters the chamber. However I've accidentally left the cap off three times now, with a nice big flame flying out the port, but because the vaporized alcohol is using the fuel hole as another jet, the flame could not ignite the inside. Still, the potential is there.
*Open stop stoves may spill heat if tipped, because of the open inner chamber. This is especially an issue in tents and on dry ground.
*Alcohol stoves, in general, fail at simmering food. This is an issue when you make store-bought meals on the trail that require "simmer 8-10 minutes". However, simmering can be accomplished by placing your pot in a Reflectix pot cozy (basically bubble wrap sandwiched between two layers of aluminum foil... "97% reflected heat"-so they claim).
Modifications
*Open top jet stove: Create a simmer lid out of a tuna can lid or lid similar in diameter to your stove. Cut a 1/4 pie section out and attach some form of handle. The simmer ring will snuff out the jets but leave the inner chamber burning, reducing heat and allowing you to simmer your food somewhat.
*pressurized jet stove: Wrap a fiberglass wick 5-8 times around the base of your stove. This will eliminate the need for a separate priming pan but will function the same way. Pour a little fuel on the wick and light.
Test Runs
Closed Pressurized Side Jet (stove acts as pot stand) with double sheet aluminum foil windscreen
See my tests here (http://ourwilderness.freezoka.com/Alcohol_Stove_Tests.xls)
More to come as tests continue
Open Flame Alcohol Stove
http://zenstoves.net/Basics/OpenFlame.jpg
Basically a dish of some kind, filled with alcohol, and lit on fire. Too simple, too open, not enough heat, horrible fuel efficiency, don't build. Period. Sorry.
Open Top Jet Alcohol Stove
http://zenstoves.net/TopBurner/TopBurner.jpg
These stoves are probably the most common because they're the easiest to make and take very little skill in assembly. Simply fill with fuel, light the inner chamber, and wait for the fuel to vaporize. The steps for assembly can be found here (http://zenstoves.net/ConstructionStep2-FuelPort.htm#Step2aOpenJetStove). The cons of this design are threefold: one, it takes multitudes longer to prime the alcohol to vaporization, you are burning your interior stove fuel for priming, and the fuel burns freely so there is less fuel efficiency. If tipped, the stove could spill lit fuel.
Pressurized Jet Alcohol Stove
http://zenstoves.net/Construction/polished.jpg
These stoves follow a similar construction pattern as the open top, but there is no cut-out section. Rather, a small hole is drilled into the bottom of one pop can as a fuel port. The port is then covered with an object to prevent a flame from entering the body (if a flame hit the vaporized fuel within the body, it could explode). The priming takes much less time (<30 sec) and the jets are higher pressure, giving better fuel economy because the alcohol is vaporizing better. Instructions can be found here (http://zenstoves.net/ConstructionStep2-FuelPort.htm#Step2bPressurizedJetStove).
Cons are that you need more dexterity in assembly as well as noting the potential for an alcohol bomb if you don't replace the fuel port cover (I use a simple metal bolt). You also will need to carry around a small dish (or lid off a soup can) for priming the stove.
Comparisons
These are the three main designs - each having many subdesigns. The open-top jet has given way to many lightweight alternatives and "simmer rings." Because of it's low-pressure output and open inner camber, covering some (or all) of the jets won't snuff the stove and will produce a simmering effect on your cooking. The pressurized jet are the favorites of backpackers because of it's fuel efficiency (compared to the open top) and it won't spill fuel or cause a fire hazard if tipped. They also burn much hotter for longer periods because of the torch-like jets they produce. My titanium pot handle turned red-hot when a jet was under it, reflected by my aluminum foil windscreen!
Fuel
Pop can stoves burn Isopropyl, Methanol, Ethanol, Everclear, and Denatured Alcohol. The cleaner the alcohol, the bluer, hotter, and less sooty the flame. Isopropyl, in concentrations exceeding 80%, burn just as well as Methanol HEET (95% Methanol). Denatured Alcohol burns hottest, if I remember correctly, and Everclear is "drinkable" so it's taxed by liquor laws making it more expensive than the other options. The better the stove is at vaporizing the fuel and forcing it out the jets, the easier the fuel will mix with air and increase heat output and length of burn.
Potential Issues
*Overpriming and constriction of heat within a reflective windscreen may overheat the alcohol of pressurized stoves, causing a rapid expansion and eventual seam burst. However this has not happened to me and I've damn near taken a blowtorch to it.
*Pressurized stoves may explode if the fuel cap is left off and a flame enters the chamber. However I've accidentally left the cap off three times now, with a nice big flame flying out the port, but because the vaporized alcohol is using the fuel hole as another jet, the flame could not ignite the inside. Still, the potential is there.
*Open stop stoves may spill heat if tipped, because of the open inner chamber. This is especially an issue in tents and on dry ground.
*Alcohol stoves, in general, fail at simmering food. This is an issue when you make store-bought meals on the trail that require "simmer 8-10 minutes". However, simmering can be accomplished by placing your pot in a Reflectix pot cozy (basically bubble wrap sandwiched between two layers of aluminum foil... "97% reflected heat"-so they claim).
Modifications
*Open top jet stove: Create a simmer lid out of a tuna can lid or lid similar in diameter to your stove. Cut a 1/4 pie section out and attach some form of handle. The simmer ring will snuff out the jets but leave the inner chamber burning, reducing heat and allowing you to simmer your food somewhat.
*pressurized jet stove: Wrap a fiberglass wick 5-8 times around the base of your stove. This will eliminate the need for a separate priming pan but will function the same way. Pour a little fuel on the wick and light.
Test Runs
Closed Pressurized Side Jet (stove acts as pot stand) with double sheet aluminum foil windscreen
See my tests here (http://ourwilderness.freezoka.com/Alcohol_Stove_Tests.xls)
More to come as tests continue