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Thread: where can I find a list for capillary-action-materials?

  1. #1 where can I find a list for capillary-action-materials? 
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    I want to compare capillary action in different materials. I would like to have a list of materials with how high it can pull water using capillary action.

    Does anyone know where to find such a list?


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  3. #2  
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    Have you tried just looking for a list of porous materials?


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    Forum Professor captaincaveman's Avatar
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    i know plants use capillary action to draw water up, do you know what the action is in trees?

    I remember reading capillary action couldn't draw fluids this high.
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    Forum Professor river_rat's Avatar
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    To my knowledge, capillary action only depends on the radius of the tube - for the formula see http://en.wikipedia.org/wiki/Capillary_action
    As is often the case with technical subjects we are presented with an unfortunate choice: an explanation that is accurate but incomprehensible, or comprehensible but wrong.
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  6. #5  
    Forum Professor captaincaveman's Avatar
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    Quote Originally Posted by river_rat
    To my knowledge, capillary action only depends on the radius of the tube - for the formula see http://en.wikipedia.org/wiki/Capillary_action

    thanks river_rat, but im pretty sure that a 150ft tree couldn't use capillary action alone. but then i could be wrong
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    Forum Professor river_rat's Avatar
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    It doesn't

    The main driving force for water in trees and almost all other plants is transpiration from the leaves - the water is literally sucked out the ground.
    As is often the case with technical subjects we are presented with an unfortunate choice: an explanation that is accurate but incomprehensible, or comprehensible but wrong.
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    Quote Originally Posted by river_rat
    It doesn't

    The main driving force for water in trees and almost all other plants is transpiration from the leaves - the water is literally sucked out the ground.
    Wouldn't that limit trees to 32 feet tall? since above that, the weight of water would form a vacuum?
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  9. #8  
    Forum Professor river_rat's Avatar
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    I dont see how, its a normal pump action and pumps are not limited to 32 feet.

    Where do you get the 32 feet from anyway? Anything above the capillary height would be forming a vaccum effect would it not?
    As is often the case with technical subjects we are presented with an unfortunate choice: an explanation that is accurate but incomprehensible, or comprehensible but wrong.
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  10. #9  
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    Quote Originally Posted by river_rat
    I dont see how, its a normal pump action and pumps are not limited to 32 feet.

    Where do you get the 32 feet from anyway? Anything above the capillary height would be forming a vaccum effect would it not?
    Transpiration as I understand it is a function of leaves, you just can't 'suck' water up more than 32 feet, as to pumps, they push the water through a pipe, that's why the first one is always at the source, where you have 'repeater' pumps.

    If you seal a tube at one end after filling it with water and lift it out of the water[keeping the other end submerged] when you get to 32 feet above the surface a vacuum wil form at the top, this is because the atmospheric pressure (14 psi) is equaled by the weight of water in a 32 foot column, if you then go higher the atmospheric pressure on the water surface is no longer sufficient to 'push' the water to the top of the tube.

    If you did the same with mercury I think it 'vacuums' at about 72.5 cm.
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    Ok, i see now what you are talking about.

    I think the osmotic pressure at the roots also plays a role and it is a combination of all three that gets the water flowing. I always thought that the main driving force was transpiration though - will have to go dust off the old biology text books.

    EDIT: found this at wikipedia http://en.wikipedia.org/wiki/Transpirational_pull
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  12. #11  
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    Quote Originally Posted by river_rat
    Ok, i see now what you are talking about.

    I think the osmotic pressure at the roots also plays a role and it is a combination of all three that gets the water flowing. I always thought that the main driving force was transpiration though - will have to go dust off the old biology text books.

    EDIT: found this at wikipedia http://en.wikipedia.org/wiki/Transpirational_pull
    I think the jury's out on the whole mechanism, If you think about the worlds tallest trees the pressure at the bottom would be enough to literally explode the trunk if it was a single column of water [200psi]. It must be more like 'passing from cell to cell' or something - if you find it post. -

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    Forum Professor river_rat's Avatar
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    Quote Originally Posted by billco
    Quote Originally Posted by river_rat
    Ok, i see now what you are talking about.

    I think the osmotic pressure at the roots also plays a role and it is a combination of all three that gets the water flowing. I always thought that the main driving force was transpiration though - will have to go dust off the old biology text books.

    EDIT: found this at wikipedia http://en.wikipedia.org/wiki/Transpirational_pull
    I think the jury's out on the whole mechanism, If you think about the worlds tallest trees the pressure at the bottom would be enough to literally explode the trunk if it was a single column of water [200psi]. It must be more like 'passing from cell to cell' or something - if you find it post. -

    Rgds, Billco
    I cant remember the actual structure of xylem - arent there any bio experts here?
    As is often the case with technical subjects we are presented with an unfortunate choice: an explanation that is accurate but incomprehensible, or comprehensible but wrong.
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    My expertise in biology is limited to a fundamental knowledge of preserving the species... :wink:
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  15. #14  
    Forum Professor river_rat's Avatar
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    Quote Originally Posted by billco
    My expertise in biology is limited to a fundamental knowledge of preserving the species... :wink:
    Lol - i thought that was innate and rather instinctual when you got down to the nuts and bolts of it!
    As is often the case with technical subjects we are presented with an unfortunate choice: an explanation that is accurate but incomprehensible, or comprehensible but wrong.
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  16. #15  
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    and there was me thinking it'd be any easy answer :wink:
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  17. #16  
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    Have you tried just looking for a list of porous materials?
    yes, did 5 pages in google. no joy.
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  18. #17  
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    Quote Originally Posted by captaincaveman
    and there was me thinking it'd be any easy answer :wink:
    No, this one's tougher than the big bang, they are still arguing. In natures battle of wits, Tall Trees 1, Humans nil!
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