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  1. #1
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    HEPA Filter for low temp (-15C)


    Hi guys, I new to this group & glad to join the group to discuss Refrigeration.I need some help for conditioning of the air. If anyone have come across the following problems, please advise.Previously, I have a fresh air system for food process. Air is conditioned through 3 AHUs to +2C & is filtered by HEPA from AAF of AAF AstoCel 1. Recently I done a upgrade of the system & brought the air temp down to -15C. However I noticed that HEPA freezed after 30 min of operation & system pressure went from 1.6KPa to 4KPa. When we revert back to the old parameters, system pressure went back to 1.6KPa.Therefore I am asking if anyone have done a project like this & have come across this problem. Also, do anyone know if there are HEPA filtration for temp as low as -10/-15C?Thanks in advance, Hui



  2. #2
    Join Date
    Feb 2012
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    Re: HEPA Filter for low temp (-15C)

    Never had this problem in particular, though I know you have to change the type of filter if you have now high relative humidity or the velocity profile changed.

    You should contact the filter supplier.

  3. #3
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    Re: HEPA Filter for low temp (-15C)

    We are currently seeking advice from AAF on the suitable type of HEPA.
    The air velocity was changed from 143 to 165m3/min

  4. #4
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    Aug 2009
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    Re: HEPA Filter for low temp (-15C)

    Your filter is not freezing up, it just becoming blocked with ice particles that are suspended in the air.
    Think of it as "Ice dust"

  5. #5
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    Re: HEPA Filter for low temp (-15C)

    Hi mad fridgie,

    That certainly ring a bell!!! I noticed the area after my -15C coil & before the HEPA to be fill with 'snow'. You know of any product on how we can 'catch' these dust out from the air before reaching the HEPA?

    Thanks, Hui
    Attached Files Attached Files

  6. #6
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    Re: HEPA Filter for low temp (-15C)

    It looks like you are working in an oversaturated region, thus the fog.

    Drying the air may help.

  7. #7
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    Oct 2007
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    manchester
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    Re: HEPA Filter for low temp (-15C)

    if its a fresh air system the surely you fiter the air then cool it-thus eliminating your hepa filters frosting up
    Quote Originally Posted by blackheart_hui View Post
    Hi guys, I new to this group & glad to join the group to discuss Refrigeration.I need some help for conditioning of the air. If anyone have come across the following problems, please advise.Previously, I have a fresh air system for food process. Air is conditioned through 3 AHUs to +2C & is filtered by HEPA from AAF of AAF AstoCel 1. Recently I done a upgrade of the system & brought the air temp down to -15C. However I noticed that HEPA freezed after 30 min of operation & system pressure went from 1.6KPa to 4KPa. When we revert back to the old parameters, system pressure went back to 1.6KPa.Therefore I am asking if anyone have done a project like this & have come across this problem. Also, do anyone know if there are HEPA filtration for temp as low as -10/-15C?Thanks in advance, Hui

  8. #8
    Join Date
    Oct 2010
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    Singapore
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    Re: HEPA Filter for low temp (-15C)

    hi guys, thanks for all your help.
    I shifted the HEPA upstream before my -15AHU. Also explained the mystery for the chocked filter. Thanks You

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