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  1. #1
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    Default Home made freeze dryer / Lyophilization

    I have a need to freeze dry some stuff, and apparently.... commercial freeze dryers aren't cheap.. and there isn't really anything on the interwebs about doing it at home.

    I'm sure what I have in mind wouldn't be nearly as effective as a big expensive commercial freeze dryer, but it may just get the job done.

    I'm figuring on getting a cheap used stand up freezer, popping an inch or two hole in the front door, and plugging it with a shop vac hose. Run the freezer with cookie sheets of stuff I need to freeze, once frozen, shut off the freezer and run the shop vac.

    I think it might just be ghetto enough to work for fishing bait and a few other small items.

    Thoughts?

  2. #2
    Shooting at the big range in heaven
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    So you want to decrease the pressure in the freezer using a shop vac?

    Respectfully,
    jkelly

  3. #3
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    Quote Originally Posted by Hiltonizer View Post
    I think it might just be ghetto enough to work ...
    I'll add that to my list of "famous last words".

  4. #4
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    Quote Originally Posted by Hiltonizer View Post
    I have a need to freeze dry some stuff, and apparently.... commercial freeze dryers aren't cheap.. and there isn't really anything on the interwebs about doing it at home.

    I'm sure what I have in mind wouldn't be nearly as effective as a big expensive commercial freeze dryer, but it may just get the job done.

    I'm figuring on getting a cheap used stand up freezer, popping an inch or two hole in the front door, and plugging it with a shop vac hose. Run the freezer with cookie sheets of stuff I need to freeze, once frozen, shut off the freezer and run the shop vac.

    I think it might just be ghetto enough to work for fishing bait and a few other small items.

    Thoughts?
    You Might want to take a look at this before you consider your path. Note the temperature needed, they are not normal freezer temperatures.

    Good luck.


    http://en.wikipedia.org/wiki/Freeze_drying
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  5. #5

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    Could you use a dehydrator? Seems a lot more straight forward.

  6. #6
    NES Member glostamon's Avatar
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    Quote Originally Posted by Hiltonizer View Post
    I have a need to freeze dry some stuff, and apparently.... commercial freeze dryers aren't cheap.. and there isn't really anything on the interwebs about doing it at home.

    I'm sure what I have in mind wouldn't be nearly as effective as a big expensive commercial freeze dryer, but it may just get the job done.

    I'm figuring on getting a cheap used stand up freezer, popping an inch or two hole in the front door, and plugging it with a shop vac hose. Run the freezer with cookie sheets of stuff I need to freeze, once frozen, shut off the freezer and run the shop vac.

    I think it might just be ghetto enough to work for fishing bait and a few other small items.

    Thoughts?
    Things that make you go ...
    "It could probably be shown by facts and figures that there is no distinctly American criminal class except Congress.Ē~ Mark Twain

  7. #7
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    I hate to be pessimistic, but I have my doubts that it will work. But I've written this post anyway to see if I can be of any help.

    A lyophilizer does not typically cool the item and vacuum it at the same time. When I was doing lyophilization for work (chemistry lab), we froze the item completely using liquid nitrogen, and then put it into the lyophilizer. The lyophilizer was just a way to put a very strong vacuum on a sealed container. So it sounds like you have the right process in your set up.

    You need to make sure that the vacuum is strong enough (a lot of commercial vacuum pumps can't get down to a low enough pressure to really dry it out). You also need to make sure that your container is air tight, and that it won't collapse under a vacuum.

    I think that there are two problems that you'll run into (maybe just one). The freezer needs to be air tight, including the hole that you cut into it. That's fairly easy to accomplish. Once a vacuum starts to be created inside, it'll pull everything tighter. The potentially bigger problem is that your shop vac might not be strong enough to pull enough of a vacuum.

    Two other things that I would suggest, if possible. The first is a release valve. If you have a freezer with a vacuum inside, and you want to open it - good luck. A valve to let air back in will be necessary and it's probably a lot easier than disconnecting your vacuum pump. Second, fight the urge to check on it all the time. You don't know exactly how long it will take, but I would bet that it will be measured in days, if not more.

  8. #8
    NES Member MA_Shooter's Avatar
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    Quote Originally Posted by zeppelinfromled View Post

    I think that there are two problems that you'll run into (maybe just one). The freezer needs to be air tight, including the hole that you cut into it. That's fairly easy to accomplish. Once a vacuum starts to be created inside, it'll pull everything tighter. The potentially bigger problem is that your shop vac might not be strong enough to pull enough of a vacuum.

    Two other things that I would suggest, if possible. The first is a release valve. If you have a freezer with a vacuum inside, and you want to open it - good luck. A valve to let air back in will be necessary and it's probably a lot easier than disconnecting your vacuum pump. Second, fight the urge to check on it all the time. You don't know exactly how long it will take, but I would bet that it will be measured in days, if not more.

    We have a lyophilizer unit at work for handling various solids....the post above identifies two huge problems. The shop vac does not provide adequate vacuum (you need millibar pressures, or lower - such as from a rotary vane pump) and even if it did, you would have to use a thick-walled glass/SS vessel to maintain that pressure. Don't worry about the condenser (LN2 trap), that's the least of your problems. Sorry....but McGyver would be proud!

  9. #9
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    Thanks for the input all.

    I'm neither a physicist, chemist, or mechanical engineer... but it was an interesting theory.

  10. #10
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    It would be a waste of a perfectly good shop vac..lol Very inventive though..

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