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What is the reason for adding propane to gas canisters and is it possible to get butane ones only. By my reckoning since it has a lower boiling point than propane then I shouldn't get the problem of it being too cold to light.Does propane have a higher calorific value?
Is it possible to get butane gas canisters for gas stoves? The only ones I can find are propane / butane mix.
Is it possible to get butane gas canisters for gas stoves? The only ones I can find are propane / butane mix.
In reply to smollett: Propane has a lower bp, so i'd guess that's the reason they add it to butane canisters.
(I'm not certain but that would be my guess)
(I'm not certain but that would be my guess)
In reply to pinkpeople53:
Oops my mistake. Got the gases the wrong way round. It's propane canisters I should be looking for. In that case why add butane?
Oops my mistake. Got the gases the wrong way round. It's propane canisters I should be looking for. In that case why add butane?
In reply to smollett: Propane has a much lower BP than butane (-42 compared with -0.5) as its a smaller molecule within the same chemical family.
Butane will therefore be a liquid below -0.5 and not escape the canister to burn easily. It also starts performing badly when the temp starts dropping towards its BP, say below +5.
Butane will release more energy per molecule during combustion as its a bigger molecule but its weighs more so I'm not sure if it will release more energy per gram. You can do the maths if you want, I can't be bothered!
You can get butane only canisters from hardware stores (B&Q etc) for blowtorches if you want to experiment,
More reading here if you're interested http://en.wikipedia.org/wiki/Alkane
Butane will therefore be a liquid below -0.5 and not escape the canister to burn easily. It also starts performing badly when the temp starts dropping towards its BP, say below +5.
Butane will release more energy per molecule during combustion as its a bigger molecule but its weighs more so I'm not sure if it will release more energy per gram. You can do the maths if you want, I can't be bothered!
You can get butane only canisters from hardware stores (B&Q etc) for blowtorches if you want to experiment,
More reading here if you're interested http://en.wikipedia.org/wiki/Alkane
In reply to smollett:
I'd guess because its either got a higher calorific value or its cheaper or both.
> (In reply to pinkpeople53)
> In that case why add butane? >
> In that case why add butane? >
I'd guess because its either got a higher calorific value or its cheaper or both.
Pure propane cylinders aren't available as far as I know, strange given that butane gets a bit difficult to burn below 4 deg C and it is often that cold in the UK.
It's worth getting a remote canister stove so you can heat the canister near the flame, turn it upside down and shake it while cooking. All these measures help to coax a decent flame from butane in cold conditions.
Keeping a spare canister inside your jacket and swapping them over from time to time is another good cold weather tip.
It's worth getting a remote canister stove so you can heat the canister near the flame, turn it upside down and shake it while cooking. All these measures help to coax a decent flame from butane in cold conditions.
Keeping a spare canister inside your jacket and swapping them over from time to time is another good cold weather tip.
In reply to the real dr gav:
A copper wire <from a each cable or similar> wrapped a few times arounf the canister and then through the flame boosts perfomance. The heat dissipates from the flame through the wire heating the canister.
Dunking the canister in the water you are heating helps too <when water is warm/hot>
I have those heating pads, you know the throw away ones - I open it at start of day and keep it in the dished base of the canister inside my titan pot. Keeps it warm all day when winter climbing.
A copper wire <from a each cable or similar> wrapped a few times arounf the canister and then through the flame boosts perfomance. The heat dissipates from the flame through the wire heating the canister.
Dunking the canister in the water you are heating helps too <when water is warm/hot>
I have those heating pads, you know the throw away ones - I open it at start of day and keep it in the dished base of the canister inside my titan pot. Keeps it warm all day when winter climbing.
In reply to the real dr gav: Pure propane is available in cylinders, just not small ones as it needs a strong, heavy tank to contain it. This because it wants to boil so puts a lot of pressure on the cylinder.
But if you mix it with butane, the boiling point rises so less pressure on the container so a less strong, lighter tank can be used.
But if you mix it with butane, the boiling point rises so less pressure on the container so a less strong, lighter tank can be used.
In reply to smollett: You can get different mixtures some have 40% propane not 30 if it makes a difference? No idea. I find the mixed ones are ok with a bit of shaking, if you are worried keep the cartridge warm in your sleeping bag or something.
In reply to smollett: I think, but I'm not sure, that it has something to do with how they burn at altitude.
In reply to smollett:
The pure propane canisters for blow torches may not have the correct screw for your stove, and they probably won't take the cannister back if you get it wrong. (the cannisters have a tmper seal on the nozzel).
Some manufacturers have a winter mix cannister. These can have either a higher percentage of propane (40% instead of 30%), or they have some isobutane instead of butane (10%). Isobutane has a lower bp than butane. Check the cylinders. These changes only improve the performance above 2C. Below that the cylinders struggle - esentially the propane and isobutane burn off first leaving the butane behind. So, if you head out with a half full canister you will struggle to keep it lit because it only contains butane. Always take fresh canisters in winter, then finish them off in summer. Cannisters also lose pressure in use, not just because they they are loosing gas, but because the gas being released extracts heat from the cannister as it expands - the cannister cools down.
you can get better performance out of cannisters by:
Sleeping with them
Insulating them from the snow whilst in use, put reflectors (foil) under and around the set.
copper coil heat conductor described above.
put hand heater pad under cnnister, then use pad in gloves/boots/gps or camera bag.
Cannister stoves with a hose are better because:
The cannister can then be dipped in the boiling water to keep heating it up.
The cannister can be turned on it's side or uupside down to enable the propane to force some liquid butane down the tube.
At altitude cannisters are almost useless, especially in the cold. It's worth investing in a multifuel stove because:
Cannisters are still not available in many european countries (e.g Corsica)
If you are melting snow for water - you'll never carry enough cannisters. for a mutiday trip - even in Scotland.
Multifel stoves can use cannisters but unfortunately are a lot heavier.
The pure propane canisters for blow torches may not have the correct screw for your stove, and they probably won't take the cannister back if you get it wrong. (the cannisters have a tmper seal on the nozzel).
Some manufacturers have a winter mix cannister. These can have either a higher percentage of propane (40% instead of 30%), or they have some isobutane instead of butane (10%). Isobutane has a lower bp than butane. Check the cylinders. These changes only improve the performance above 2C. Below that the cylinders struggle - esentially the propane and isobutane burn off first leaving the butane behind. So, if you head out with a half full canister you will struggle to keep it lit because it only contains butane. Always take fresh canisters in winter, then finish them off in summer. Cannisters also lose pressure in use, not just because they they are loosing gas, but because the gas being released extracts heat from the cannister as it expands - the cannister cools down.
you can get better performance out of cannisters by:
Sleeping with them
Insulating them from the snow whilst in use, put reflectors (foil) under and around the set.
copper coil heat conductor described above.
put hand heater pad under cnnister, then use pad in gloves/boots/gps or camera bag.
Cannister stoves with a hose are better because:
The cannister can then be dipped in the boiling water to keep heating it up.
The cannister can be turned on it's side or uupside down to enable the propane to force some liquid butane down the tube.
At altitude cannisters are almost useless, especially in the cold. It's worth investing in a multifuel stove because:
Cannisters are still not available in many european countries (e.g Corsica)
If you are melting snow for water - you'll never carry enough cannisters. for a mutiday trip - even in Scotland.
Multifel stoves can use cannisters but unfortunately are a lot heavier.
In reply to Venture-Out: If you are melting snow for water - you'll never carry enough cannisters. for a mutiday trip - even in Scotland.
Not necessarily, i used one canister for 3 people over two days for melting snow. It worked fine in Scotland, I think it has more to do with what stove you use. I have a Jetboil, which alongside the MSR Reactor, is the most efficent stove on the market.
Although I completley agree about the altitude and the foreign uses. The ability to just fill your stove at a petrol pump certainly has its advantages...
Not necessarily, i used one canister for 3 people over two days for melting snow. It worked fine in Scotland, I think it has more to do with what stove you use. I have a Jetboil, which alongside the MSR Reactor, is the most efficent stove on the market.
Although I completley agree about the altitude and the foreign uses. The ability to just fill your stove at a petrol pump certainly has its advantages...
In reply to Richiehill: I would also add that we used gas (Isobutane/Propane mix with MSR pocket rockets) in the chilean andes last month for melting snow at altitudes between 4300 and 5300m with little problem. So you definitely can use gas in relatively cold places and at altitude - really depends on how high and how cold + canister availability.
In reply to smollett:
As with most bits of advice on using gas stoves in the cold this comes with a little warning: Screwing around with gas cylinders can cause loss of eyebrows and damage to your tent, don't blame me if something blows up.
Gas cylinders-wise anything that has a 7/16" UNEF threaded lindal valve on it should fit a modern gas stove. Generally you won't find pure propane because of the higher pressures involved though. It is also important to realise that the nozzles are bored for a specific fuel, generally I think it is Propane>Butane>White Gas>Petrol>Diesel. Using the wrong sized nozzle in a multifuel stove will cause flame lift or poor heat output.
With mixed gasses the lighter stuff tends to come across more easily - so the propane burns quicker leaving you with a more butane rich mix. This doesn't work as well in the cold.
It is also important to remember that gas cylinders cool down as gas is released:
DO NOT HOLD ONTO A GAS CYLINDER WITH BARE HANDS TO WARM IT WHILE THE STOVE IS RUNNING! You can easily freeze the cylinder onto your fingers in cold weather, the faster the gas is going through the stove the faster the cooling.
You can get more out of the cylinder in 2 ways:
-Heating the cylinder.
-Turning the cylinder upside down.
Heating the cylinder is dangerous, if you don't understand the risks then please don't try it. The easiest ways to heat the cylinder are with a tightly fitted wind shield or a heat exchanger (flattened bit of copper pipe etc). Getting this wrong can lead to a big bang, you don't want to be within 10m of this when it happens. Shrapnel isn't funny or clever.
Turning the cylinder upside down and drawing off liquid is also not safe. You get a BIG flare up when you turn the cylinder upside down and you need to run with the valve almost completely closed initially as you are putting much more fuel down the pipe. This will only work with a stove with a pre-heater (either a coil or block).
If you've got a remote canister stove the easiest thing is to drop the cylinder into your pan as you are heating water, but don't let the cylinder get above about 60C!
As with most bits of advice on using gas stoves in the cold this comes with a little warning: Screwing around with gas cylinders can cause loss of eyebrows and damage to your tent, don't blame me if something blows up.
Gas cylinders-wise anything that has a 7/16" UNEF threaded lindal valve on it should fit a modern gas stove. Generally you won't find pure propane because of the higher pressures involved though. It is also important to realise that the nozzles are bored for a specific fuel, generally I think it is Propane>Butane>White Gas>Petrol>Diesel. Using the wrong sized nozzle in a multifuel stove will cause flame lift or poor heat output.
With mixed gasses the lighter stuff tends to come across more easily - so the propane burns quicker leaving you with a more butane rich mix. This doesn't work as well in the cold.
It is also important to remember that gas cylinders cool down as gas is released:
DO NOT HOLD ONTO A GAS CYLINDER WITH BARE HANDS TO WARM IT WHILE THE STOVE IS RUNNING! You can easily freeze the cylinder onto your fingers in cold weather, the faster the gas is going through the stove the faster the cooling.
You can get more out of the cylinder in 2 ways:
-Heating the cylinder.
-Turning the cylinder upside down.
Heating the cylinder is dangerous, if you don't understand the risks then please don't try it. The easiest ways to heat the cylinder are with a tightly fitted wind shield or a heat exchanger (flattened bit of copper pipe etc). Getting this wrong can lead to a big bang, you don't want to be within 10m of this when it happens. Shrapnel isn't funny or clever.
Turning the cylinder upside down and drawing off liquid is also not safe. You get a BIG flare up when you turn the cylinder upside down and you need to run with the valve almost completely closed initially as you are putting much more fuel down the pipe. This will only work with a stove with a pre-heater (either a coil or block).
If you've got a remote canister stove the easiest thing is to drop the cylinder into your pan as you are heating water, but don't let the cylinder get above about 60C!
In reply to smollett:
Lots of stuff on the web about improving performance of canister stoves in cold weather...but here's what has worked for me in the uk (down to about -5?)
As has already been mentioned, using a remote canister stove with a preheating tube (that passes the gas through the flame) means that you can turn the cannister upside down if you need to. The preheating tube means that as long as you only do this AFTER the stove is lit, it shouldn't flare up (has never happened to me!).
Also you can stand the canister in a bowl/pan of water. It doesn't even need to be hot water, since the evaporation if the gas in the canister is what causes the cooling, far more than ambient temps.
I've never resorted to storing the gas in my sleeping bag or clothes (I do keep it inside the inner of my tent though) since as soon as you turn the stove on the canister cools dramatically - so IME the additional warmth is lost almost straight.
If all that fails, then use a petrol stove!
HTH
Si
Lots of stuff on the web about improving performance of canister stoves in cold weather...but here's what has worked for me in the uk (down to about -5?)
As has already been mentioned, using a remote canister stove with a preheating tube (that passes the gas through the flame) means that you can turn the cannister upside down if you need to. The preheating tube means that as long as you only do this AFTER the stove is lit, it shouldn't flare up (has never happened to me!).
Also you can stand the canister in a bowl/pan of water. It doesn't even need to be hot water, since the evaporation if the gas in the canister is what causes the cooling, far more than ambient temps.
I've never resorted to storing the gas in my sleeping bag or clothes (I do keep it inside the inner of my tent though) since as soon as you turn the stove on the canister cools dramatically - so IME the additional warmth is lost almost straight.
If all that fails, then use a petrol stove!
HTH
Si
In reply to Venture-Out:
That is a good tip.
> Cannister stoves with a hose are better because:
> The cannister can then be dipped in the boiling water to keep heating it up.
> The cannister can then be dipped in the boiling water to keep heating it up.
That is a good tip.
In reply to SCC:
With I modern tent with a sown-in groundsheet, this might not be a good idea. Gas is heavier than air, so if there's a small leak from the can you end up with a pool of oxygen-displacing gas in your tent while you sleep.
> (In reply to smollett)
> I've never resorted to storing the gas in my sleeping bag or clothes (I do keep it inside the inner of my tent though)
> I've never resorted to storing the gas in my sleeping bag or clothes (I do keep it inside the inner of my tent though)
With I modern tent with a sown-in groundsheet, this might not be a good idea. Gas is heavier than air, so if there's a small leak from the can you end up with a pool of oxygen-displacing gas in your tent while you sleep.
In reply to Jack B:
Small leak? I've never seen a cylinder develop a small leak, big leaks yes but you notice those I suppose that may be a problem if you left it connected to a stove with a faulty valve. A well maintained stove shouldn't give you any problems unless you are using it in really extreme conditions.
Small leak? I've never seen a cylinder develop a small leak, big leaks yes but you notice those I suppose that may be a problem if you left it connected to a stove with a faulty valve. A well maintained stove shouldn't give you any problems unless you are using it in really extreme conditions.
In reply to Reach>Talent:
Admitedly yes, such leaks are rare. Damaged or incompletley shut valves and poor or damaged seals where the stove screws into the can are the main culprits AFAIK, and that can be avoided by disconecting the cylinder (if it's a screw on type). A piece of grit or dirt in the seal on the cylinder could cause a small leak, but I've never heard of it being a problem.
Admitedly yes, such leaks are rare. Damaged or incompletley shut valves and poor or damaged seals where the stove screws into the can are the main culprits AFAIK, and that can be avoided by disconecting the cylinder (if it's a screw on type). A piece of grit or dirt in the seal on the cylinder could cause a small leak, but I've never heard of it being a problem.
In reply to Jack B:
I've never seen or heard of a lindal valve failing, except under very high pressure or temperature (incidentally this gave rise to a very stupid sport called Shrapnel Cricket, played purely by members of my immediate family). Generally if something doesn't seal it makes a fair bit of noise, so I think you'd notice something like an o-ring going.
I've never seen or heard of a lindal valve failing, except under very high pressure or temperature (incidentally this gave rise to a very stupid sport called Shrapnel Cricket, played purely by members of my immediate family). Generally if something doesn't seal it makes a fair bit of noise, so I think you'd notice something like an o-ring going.
In reply to Reach>Talent & others:
I should have emphasised that the cannister is disconnected from the stove.
I have seen the result of a faulty valve. I unscrewed a cannister after a weeks use (in summer, so not stored in the tent) and it failed to reseal - gas everywhere. Fortunately we were packing up and no-one had a stove lit nearby.
Should have tried shrapnel cricket, but just turned it upsdie down on the ground a long way from us and our tents!
Si
I should have emphasised that the cannister is disconnected from the stove.
I have seen the result of a faulty valve. I unscrewed a cannister after a weeks use (in summer, so not stored in the tent) and it failed to reseal - gas everywhere. Fortunately we were packing up and no-one had a stove lit nearby.
Should have tried shrapnel cricket, but just turned it upsdie down on the ground a long way from us and our tents!
Si
In reply to SCC:
Shrapnel cricket requires quite specialist equipment The Bowler is a large stainless steel incinerator (constructed from an old dewar flask), the fielders all wear safety glasses and welding gloves. Optional equipment includes a safety 'beer jacket'
Shrapnel cricket requires quite specialist equipment The Bowler is a large stainless steel incinerator (constructed from an old dewar flask), the fielders all wear safety glasses and welding gloves. Optional equipment includes a safety 'beer jacket'
In reply to Reach>Talent: As kids we used to play the version called French Shrapnel Cricket with open fires and deodorant cans...
In reply to Removed User:
A tin of beans provides a bit of extra entertainment, much longer delay than a can of deodorant.
A tin of beans provides a bit of extra entertainment, much longer delay than a can of deodorant.
In reply to smollett: propane is added to butane to reduce the boiling point of the mixture so that gas is produced at lower temperatures. Unfortunately the propane gets used up quickly: a half-full canister has little propane left and is useless when cold.
This can be avoided with a remote canister stove which has a vapouriser tube IF the canster is ALWAYS used upside down. Do not use the canister upright and then invert it when the pressure drops - this is too late as the propane has already gone.
Technical explanation <a href="http://www.scunnered.pwp.blueyonder.co.uk/Low_Temp_Gas_Stove.htm" target="_blank">here</a>
Coleman do make pure propane canisters for some of their stoves but they are big and heavy
This can be avoided with a remote canister stove which has a vapouriser tube IF the canster is ALWAYS used upside down. Do not use the canister upright and then invert it when the pressure drops - this is too late as the propane has already gone.
Technical explanation <a href="http://www.scunnered.pwp.blueyonder.co.uk/Low_Temp_Gas_Stove.htm" target="_blank">here</a>
Coleman do make pure propane canisters for some of their stoves but they are big and heavy
In reply to Reach>Talent:
Buying a stove with a pre-heat coil that allow the use of an inverted, liquid feed canister is the best way of dealing with gas cooking at low temperatures.
Alternatively, piss into a pot and dunk the cylinder in that; the warmth from the piss will evaporate the gas. You may end up with a large piss popsicle, though...
> This will only work with a stove with a pre-heater (either a coil or block).
Buying a stove with a pre-heat coil that allow the use of an inverted, liquid feed canister is the best way of dealing with gas cooking at low temperatures.
Alternatively, piss into a pot and dunk the cylinder in that; the warmth from the piss will evaporate the gas. You may end up with a large piss popsicle, though...
In reply to captain paranoia:
You'll end up with a pissicle fairly fast at low temps. A pre-heater is definitely the way forward.
You'll end up with a pissicle fairly fast at low temps. A pre-heater is definitely the way forward.
In reply to Reach>Talent:
Let's run the numbers out of curiosity...
Let's say we're using pure butane, which has a latent heat of vaporisation of 21kJ/mol, and a molecular mass of 58g/mol.
Let's say we pee 250ml at body temperature, 37C, and this is essentially water with a specific heat capacity of 4.2J/g/C.
Boiling 500ml of water takes about 10g of gas (I'm being generous).
So, we need 21k*10/58 = 3620J to vaporise the 10g of butane.
We can calculate the temperature drop caused by the vaporisation of the butane:
dT = -3620/(250*4.2)
dT = -3.45C
So the pee ends up at a temperature of 33.55C. Not even close to freezing.
If you leave the pot of piss standing around for a while in the cold, then yes, it will freeze. But it won't freeze as a result of the evaporation of the gas; you'd have to use an entire 100g cylinder of gas to get the piss close to freezing.
We also need to consider how much the cold canister of gas cools the piss before we start evaporation. We can do this by taking an energy balance around 0C, and considering the masses of pee, gas and canister, and their heat capacities. We can show that, assuming the gas starts at -10C, the pee will be cooled by about 10C before we start:
dHc (iron) = 0.44J/g/C
dHc (butane) = 2.28J/g/C
Hpee = 37 * 4.2 * 250 = 38850 J
Hgas = -10 * (0.44 * 100 + 2.28 *100) = -2720 J
Hsum = 38850 - 2720 = 36130 J
Tsum = 36130/(250*4.2+100*0.44+100*2.28) = 27.3 C
I'd still recommend the pre-heater tube, though...
> You'll end up with a pissicle fairly fast at low temps. A pre-heater is definitely the way forward.
Let's run the numbers out of curiosity...
Let's say we're using pure butane, which has a latent heat of vaporisation of 21kJ/mol, and a molecular mass of 58g/mol.
Let's say we pee 250ml at body temperature, 37C, and this is essentially water with a specific heat capacity of 4.2J/g/C.
Boiling 500ml of water takes about 10g of gas (I'm being generous).
So, we need 21k*10/58 = 3620J to vaporise the 10g of butane.
We can calculate the temperature drop caused by the vaporisation of the butane:
dT = -3620/(250*4.2)
dT = -3.45C
So the pee ends up at a temperature of 33.55C. Not even close to freezing.
If you leave the pot of piss standing around for a while in the cold, then yes, it will freeze. But it won't freeze as a result of the evaporation of the gas; you'd have to use an entire 100g cylinder of gas to get the piss close to freezing.
We also need to consider how much the cold canister of gas cools the piss before we start evaporation. We can do this by taking an energy balance around 0C, and considering the masses of pee, gas and canister, and their heat capacities. We can show that, assuming the gas starts at -10C, the pee will be cooled by about 10C before we start:
dHc (iron) = 0.44J/g/C
dHc (butane) = 2.28J/g/C
Hpee = 37 * 4.2 * 250 = 38850 J
Hgas = -10 * (0.44 * 100 + 2.28 *100) = -2720 J
Hsum = 38850 - 2720 = 36130 J
Tsum = 36130/(250*4.2+100*0.44+100*2.28) = 27.3 C
I'd still recommend the pre-heater tube, though...
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