Drinking water from snow question

[nazdarovye]

No it doesen't necessarily. It takes 80 calories to transform a gram of ice at 0C into a gram of water at 0C (Ie to just melt it), but it takes 100 calories (slightly less at elevation) to bring water from 0C to 100C.

Actually, that means that it takes almost twice as much energy to melt the snow:

80 + 100 = 180 calories to get snow to boiling.

Only 100 calories to get water to boiling.

If you're just melting the snow to 0° water, then you can just use the stream water at 0° and use no calories, compared to the 80 for the snow. Either would need to be treated with chemicals or filtered through a purifier just to be safe.

 

[Pete_Hickey]

. Either would need to be treated with chemicals or filtered through a purifier just to be safe.

This is debatable. Many (most?) do not boil/treat clean snow.

 

[Mad Townie]

However...
The snow may be colder than 0C.
You may want the water warmer than 0C for drinking
There are certain inefficiencies in trying to warm a solid.

I always thought the reason snow took longer than ice was the fact that, with snow, you're heating an awful lot of air along with the H2O. I could be wrong, though.

 

[Pete_Hickey]

I always thought the reason snow took longer than ice was the fact that, with snow, you're heating an awful lot of air along with the H2O. I could be wrong, though.

These are the inefficiencies I spoke about. Heating the air does not require much energy. The air is an insulator, and you can heat crystals to boiling without transferring the heat to nearby crystals. This is why putting water in the pot, then adding snow little by little is good. Not really a difference between snow/ice here. Just in a dry pot.

 

[DougPaul]

The air is an insulator, and you can heat crystals to boiling without transferring the heat to nearby crystals. This is why putting water in the pot, then adding snow little by little is good. Not really a difference between snow/ice here. Just in a dry pot.

I was taught (way back in winter school) that the reason for starting with water in the pot was to avoid melting a hole in the aluminum. (Make sure that you have enough water or add a small enough amount of snow that the snow does not soak up all the water.)

Haven't done it myself, but I have heard of people melting a dry pot...

If you must start with snow use only a small amount so it cannot stick to the sides and heat gently until you have enough liquid water.

I suspect that the water also improves the heat transfer to the snow by a small amount. Probably not enough to worry about.

Also snow starts by condensing on some airborne particulate. Frequently a particle of pollution these days... And pathogen containing particles can blow around and end up in clean appearing snow. I bring my melted snow to a boil before using/adding food.

Doug

 

[Pete_Hickey]

I was taught (way back in winter school) that the reason for starting with water in the pot was to avoid melting a hole in the aluminum. .......

Haven't done it myself, but I have heard of people melting a dry pot...

Jeepers! Don'T people observe what is happening. If y
ou put snow in a pot and heat it that much, it makes a LOT of noise. That should give a clue that something isn't right before your pot melts.

 

[Lawn Sale]

Hmmm...

I don't know, will the stove get hotter than 1,221°F? That's the melting point of aluminum according to my little black book. I had heard (once again, not done it myself) that it's to avoid burning the snow, so the water won't get a burned taste to it.

Time to haul out the Dragonfly and experiment I guess. Maybe I'll hook up the Whisperlite, I just picked up a stove body and think I may have successfully adapted my Dragonfly pump to it. I'll let you know tomorrow!

 

[Lawn Sale]

I used an MSR Dragonfly near max pressure with Coleman Fuel and an aluminum picnic table cloth holder as the instrument of choice, in my kitchen (can you tell I live alone?). I'll test the Whisperlite tomorrow so if it doesn't work I won't burn the house down (that would be bad).

Well, it's not totally conclusive, but I was unable to burn through, or even get to the melting point of, the aluminum. I was able to get it hot enough so the outer coating bubbled off, and it was emitting pretty yellow flames, but it didn't get even remotely pliable after 7 minutes on maximum. I have no idea of what temperature it attained, and I'm not sure if the infrared thermometer we have at work goes that high, but I'll look tomorrow.

 

[Oldsmores]

I used an MSR Dragonfly near max pressure with Coleman Fuel and an aluminum picnic table cloth holder as the instrument of choice, in my kitchen (can you tell I live alone?). I'll test the Whisperlite tomorrow so if it doesn't work I won't burn the house down (that would be bad).

Well, it's not totally conclusive, but I was unable to burn through, or even get to the melting point of, the aluminum. I was able to get it hot enough so the outer coating bubbled off, and it was emitting pretty yellow flames, but it didn't get even remotely pliable after 7 minutes on maximum. I have no idea of what temperature it attained, and I'm not sure if the infrared thermometer we have at work goes that high, but I'll look tomorrow.

Lawn, you've got entirely too much time on your hands.

 

[Bluethroatedone]

Burn snow?

I'm not sure I'm familiar with that concept....

 

[DougPaul]

Jeepers! Don'T people observe what is happening. If you put snow in a pot and heat it that much, it makes a LOT of noise. That should give a clue that something isn't right before your pot melts.

I wasn't there, but it has happened.

Perhaps they can't hear the crackling noise over the "roarer" burner. Or they went off to set up the tent. In any case, it is rather inconvient to be out in winter without a functioning pot...

I have observed soaking up all of the water in too much snow that is the precursor to melting the pot.

Lawn Sale:
maybe you should try an XGK?

I have warped the bottom of an aluminum pot in my kitchen when I got distracted, forgot about it, and boiled the water away (gas stove). It does produce a crackling noise and a scorched smell. Have no idea how close it got to melting. (Pot still works.)

Doug

 

[DougPaul]

Burn snow?

I'm not sure I'm familiar with that concept....

It's like burning water, except colder.

Doug

 

[Neil]

I've melted a hole in an aluminum pot over a campfire, it's real easy to do.


For melting snow I add just a few spoonfuls of snow at first, then a few more etc. until I have some water. Then you can add increasing quantities of snow. If you fill the pot up with snow and plunk it on a heat source the water is wicked up into the snow and the flame acts like a welder's torch on the pot's dry bottom.