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  1. #1
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    11-13-2009
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    Default Frozen sawyer ??

    I just got off the phone with Sawyer. I asked her about how to tell if your sawyer got frozen? I mentioned the turkey pop up kind of thing, and the colored strip in your phone to tell if it got wet. She said any kind of frozen sensor would be crazy expensive.
    I also asked her if blowing out the filter in below freezing weather might help. She said that would be even worse. If the filter was full and froze there's a chance both sides of the membrane would freeze and when thawed just might remain intact.
    If one side of the membrane has water and the other air, there's no chance the membrane would remain intact.
    The Sawyer uses the same stuff as dialysis filters.
    FYI

  2. #2
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    Default

    Keeping a Sawyer from freezing and worrying about it is simply not worth it. Better to switch to aquamira and relax.

  3. #3
    Registered User Ktaadn's Avatar
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    Default

    Here we go again

  4. #4
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    Default

    I have used 0.1 um filters in the lab to sterilize solutions. What we observe is that when we were done filtering, we could not force air through the wet filter (we pushed the solution through with a large syringe - just like the ones that come with the Sawyer). You know this because when the solution has gone through the filter, you could push very hard on the syringe plunger with no noticeable change in air pressure, and every time your press and release the compressed air in the syringe pushes the plunger back to the same point. This of course requires that your system be air tight. We would always do this test because sometimes the disposable filter membranes would break or not seal properly. If the filter didn't pass the pressure test, we would filter again.

    The Sawyer filters also have a 0.1 um pore size and mine behaves exactly the same way. I use an adapter to attach a 900 Evernew Water Carry bag to collect water on the clean side of my filter. To backflush, I attach a half a bag of clean water to the filter and push it backwards through the filter. When done flushing, I try to push the air remaining in the bag through the filter. When the filter is wet, I can not put any air through the filter (even when applying much more pressure than is needed to force water through filter). If I could push air through a wet filter, then I would worry that the filter membrane has been compromised and I would replace it.

    Three IMPORTANT points:

    1. This test only works on wet filters. Air will go through an intact dry filter (I'm not sure why, but this is what I have observed)

    2. To my knowledge, no one (including myself) has ever tested to find if this method is reliable for determining if a filter is still working. As I said above, if it failed this test, I would definitely replace the filter. I can not make any promise that passing the test proves the filter is intact.

    3. This behavior would predict that air bubbles in a filter may reduce flow rates. I take care to keep air bubbles from being squeezed into the filter when in use. I will also tap the filter to dislodge air bubbles trapped in the manifold. I will also invert the filter to allow air to escape the clean side (not sure if this helps or not).

  5. #5

    Default

    This is before the fact, but you can probably run everclear alcohol or vodka through the Sawyer to avoid any residual moisture freezing it.

  6. #6
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    Default

    Noe there's an idea !!

  7. #7
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    Default

    Quote Originally Posted by squeezebox View Post
    Noe there's an idea !!
    I'll call her back tomorrow.

  8. #8
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    Default

    In freezing temps I carry mine in my pants pocket with my bandanna on one side of it and the other side of it againest my leg. Then at night I toss in the foot box of my quilt. No problem in 3 years.

  9. #9
    Registered User egilbe's Avatar
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    10-18-2014
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    Lewiston and Biddeford, Maine
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    Default

    Throw it out and buy a new one. $30. Is it worth it?

  10. #10

    Default

    I like the everclear idea! I purge it with the syringe and put it in a ziplock then toss it in the end of my sleeping bag. 2 winters good so far; if I ever had a doubt it is only $20 to replace.

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