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How to remove moisture from a gas?

  1. Feb 24, 2010 #1
    Whats a simple and easy way to remove moisture from a gas, for example H2 or N2 with some water vapor mixed in it. Do those dryers that you often find on industrial air compressors remove almost all the humidity from the air? The only thing that I can think of is to cool the air below zero, let all the water condense, and then reheat the gas. But this method doesn't seem very practical and I'm wondering there is a better way.
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  3. Feb 24, 2010 #2


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    Usual way is cooling, eg LN2 trap if you have some LN2 lying around.
    Or an absorber, ( eg Linde Molecular Sieve) the sieve material works best if you can keep it cool and ultimately will saturate and need drying out.
  4. Feb 24, 2010 #3


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    Hi Topher. Is this to remove moisture from a flow inside a piping system? If so, you could start with a http://www.velcon.com/cartridges/coalescer.html" [Broken]. They'll remove gross water contamination. When a gas such as air is compressed, it can't hold as much water (per unit mass) so water often comes out downstream of air compressors and is removed with a coelescer.

    You could also use a desiccant which removes water vapor from either a piping system or could be used to remove water from a stationary volume of air. I've also seen http://www.google.com/search?hl=en&q=molecular+sieve+desiccant&aq=f&aqi=g2&aql=&oq=" used in piping systems to bring dew points down to very low levels.

    If this is for a house or enclosed volume of air, a dehumidifier will do the job.
    Last edited by a moderator: May 4, 2017
  5. Feb 25, 2010 #4
    I guess you could say that. The application is an electrolyzer where I am trying to store H2 in a hydride and O2 in an accumulator. For both gases, the storage mechanisms require the gases to be as dry as possible. I'm thinking of putting some trap inline with the outlet that contains some silica decant which I can periodically remove to dry out.
  6. Feb 25, 2010 #5


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    You should get zeolite/mol sieve rather than just silica gel, 5nm power size if normal for water.
    It works a lot better if you can keep it cool, doesn't have to be refrigerated but you don't want it just above the compressor motor.

    You might want a simpler filter first if you think you will have oil from the compressor - oil kills mol sieve.
    Drying it out is just a case of putting it in a regular warm oven (>100c) for an hour and putting it back in while still hot.
  7. Feb 25, 2010 #6


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    Desiccant dryers will get air down to a -40 dew point. They do work but are expensive. I don't know of any small units.
  8. Feb 26, 2010 #7
    we have a refridgeration unit on our shop air
    it works very well
    the compressors are outside and we never have any water in the system in house(houston always has high RH, so that is saying something)

  9. Mar 1, 2010 #8

    Ranger Mike

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    lot of dryers at mcmaster -carr

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