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  1. #14
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    Since it has been many years since I have been in a chemistry classroom, those who have been there more recently might enjoy this article:

    http://pubs.acs.org/doi/abs/10.1021/jp962442w

    I have been wrong before, and I no doubt will be again, but I am always trying to apply what I have learned.
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    2 Tim 3:16-17

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  2. #15
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    Quote Originally Posted by timebuilder View Post
    I don't have a degree in chemistry, but I was taught that osmotic equilibrium applies equally to the distribution of a vapor as well as a liquid. This leads me to believe that leaving the Nitrogen in the system for a time allows for the water that is already in vapor form to be equally distributed throughout the gas.

    Now, replacing the damp atmospheric air with a dry gas at room temperature would no doubt allow for more liquid water to become a vapor, since the rate of evaporation of water is dependent on the moisture in the air that surrounds it.

    Or, in this case, the dry Nitrogen.
    I agree.... air is full of moisture or dependent on the humidity... can be relatively dry to saturated.... using dry nitrogen that most of us use... it is just that... dry. Using N2 allows it to absorb the moisture and when released the moisture comes out with the N2 (not all... thats why we evac!)
    Here is a link to Nitrogen.... http://www.webelements.com/nitrogen/
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  3. #16
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    Quote Originally Posted by timebuilder View Post
    I don't have a degree in chemistry, but I was taught that osmotic equilibrium applies equally to the distribution of a vapor as well as a liquid. This leads me to believe that leaving the Nitrogen in the system for a time allows for the water that is already in vapor form to be equally distributed throughout the gas.
    That is correct, as long as there is no chemical interaction all gases will reach a state of equilibrium. That is to say there is no stratifcation base on weight of the gas. If you have a bottle that's half helium and half nitrogen the helium won't all end up on top. Same principle applies to carbon monoxide.

    Now, replacing the damp atmospheric air with a dry gas at room temperature would no doubt allow for more liquid water to become a vapor, since the rate of evaporation of water is dependent on the moisture in the air that surrounds it.
    Sort of. The rate of evaporation is determined by the surface area of the water temperature and pressure. Liquid water will evaporate at this rate until the air becomes saturated (or you run out of liquid water). The saturation occurs because at that concentration the water molecules polar attraction to each other results in them reforming into liquid water. The only effect the nitrogen has is on the pressure.

    The Concept of Saturation

  4. #17
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    Quote Originally Posted by Alden_Sloe View Post
    That is correct, as long as there is no chemical interaction all gases will reach a state of equilibrium. That is to say there is no stratifcation base on weight of the gas. If you have a bottle that's half helium and half nitrogen the helium won't all end up on top. Same principle applies to carbon monoxide.


    Sort of. The rate of evaporation is determined by the surface area of the water temperature and pressure. Liquid water will evaporate at this rate until the air becomes saturated (or you run out of liquid water). The saturation occurs because at that concentration the water molecules polar attraction to each other results in them reforming into liquid water. The only effect the nitrogen has is on the pressure.

    The Concept of Saturation
    This is one of those times when I wish I had taken the advanced Chem and Physics classes at NYU when I had the chance.

    If I grasp what you have said here, the rate of evaporation does not change regardless of the level of moisture already in the Nitrogen being introduced into the system, but instead, the level of moisture in the Nitrogen would merely control how much additional moisture could be taken on by the Nitrogen. Also, from my study of Meteorology, the temperature and pressure of the Nitrogen controls how much moisture it can take on.
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  5. #18
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    Ok Ok.... I quit!
    Now I wish I had gone to college for just this very reason! I loved chemistry..... but no,... I had to go Navy.....
    Silent Service........ Death From Below!

    Somewhere in Kansas, a town found a village idiot!

  6. #19
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    Quote Originally Posted by timebuilder View Post
    the level of moisture in the Nitrogen would merely control how much additional moisture could be taken on by the Nitrogen. Also, from my study of Meteorology, the temperature and pressure of the Nitrogen controls how much moisture it can take on.
    That's it. I guess theoretically the addition of water vapor to the mix increases the pressure (more gas molecules in the same enclosed volume) but I suspect in real life that doesn't have much effect once you factor in stuff like temperature change, expansion of the lines, leakage. I would hope there's not too much moisture in the lines to begin with. Anybody actually observe a pressure increase above atmospheric after filling a line with nitrogen?

  7. #20
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    So what if we introduced a chemical like say ammonia to attach itself to the water? Would the removal of the ammonia take the water with it, or would it increase the boiling point of the water, thus, dropping the water off on its way out??

  8. #21
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    Probably eat through the copper before you got it out.
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    How many times must one fix something before it is fixed?

  9. #22
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    Quote Originally Posted by beenthere View Post
    Probably eat through the copper before you got it out.
    I think you are right. We'd need something that was not going to actively corrode copper, and if it left a residue behind, said residue would have to be basically inert in the system.
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  10. #23
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    Quote Originally Posted by Bubbleheadski View Post
    Ok Ok.... I quit!
    Now I wish I had gone to college for just this very reason! I loved chemistry..... but no,... I had to go Navy.....
    What, too late for you to take advantage of the GI Bill?

    Hey, I knew one of the very few Navy guys that had all three Navy experiences: underwater, on the water, and above the water. When I met him, he was in his 70's (a few years ago) and he was a Commander.
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  11. #24
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    Not sure what you're suggesting. Introduce ammonia vapor to the system? An ammonia water solution would indeed have a lower boiling point (one of the few things that does) but even with a high pressure you'd be hard pressed to force any of it into solution. Even if you could it wouldn't do you much good. The vapor pressure of the ammonia is much lower than water so when you evacuate it's going to be driven off before you get much water to evaporate. Then you're back to having "pure" water again. The ammonia and water separate as gases so I'm not sure what you mean by "attach itself to the water".

    You'd have to recapture all of the ammonia which would be a pain. Just dealing with the stuff is a pain and as beenthere pointed out it reacts with copper. In chemistry sometimes they use an acetone rinse to dry equipment but I don't think you want to be pumping acetone into system. It's nasty stuff too. I'm pretty sure if there were a magic bullet someone would have figured it out by now.

  12. #25
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    Quote Originally Posted by Alden_Sloe View Post
    Not sure what you're suggesting. Introduce ammonia vapor to the system? An ammonia water solution would indeed have a lower boiling point (one of the few things that does) but even with a high pressure you'd be hard pressed to force any of it into solution. Even if you could it wouldn't do you much good. The vapor pressure of the ammonia is much lower than water so when you evacuate it's going to be driven off before you get much water to evaporate. Then you're back to having "pure" water again. The ammonia and water separate as gases so I'm not sure what you mean by "attach itself to the water".

    You'd have to recapture all of the ammonia which would be a pain. Just dealing with the stuff is a pain and as beenthere pointed out it reacts with copper. In chemistry sometimes they use an acetone rinse to dry equipment but I don't think you want to be pumping acetone into system. It's nasty stuff too. I'm pretty sure if there were a magic bullet someone would have figured it out by now.
    True.

    There is very little under the sun that is "new." If a safe, easy, and speedy substance was found to get water out of a system, there would be a new multi-millionaire.
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  13. #26
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    Quote Originally Posted by timebuilder View Post
    What, too late for you to take advantage of the GI Bill?

    Hey, I knew one of the very few Navy guys that had all three Navy experiences: underwater, on the water, and above the water. When I met him, he was in his 70's (a few years ago) and he was a Commander.
    Nah... I came in after the old GI Bill by about.... 2 yrs maybe.... and before the new GI bill... we had VEAP... which I think sucked rotten eggs. Did I tell you I was accepted to NC State and was going to major in Textile chemistry??? Even had a room reserved in the dorms which is uncommon for a freshman at NCSU, But Dad talked me into the military.... which I really dont mind cause I loved the submarine service!

    well as an air force brat I have flown above the water..... but I actually went on a P-3 training flight while we were in Portsmouth NH (Kittery Me.) for overhaul.... Of course i was SS qualified so that gives me under.... AND.... I was on a Submarine Tender that put out to sea at least one week every three months. Of course on the sub you have to attain your highest watch station qualifications.....divisional and ship, on the sub tender I qualifies CIC watch supervisor on my second run... (they made me wait cause i would have been done with all qualifications on my first run), then The OS2 and I stood port and starboard watches supervising the 4 CIC watch sections... (I was pretty proud of that since i hadnt been there long and there were more senior E6's standing regular supe watches.)
    So... I was under... on and over (kinda) plus I even went to shore duty!
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