You can make a gravity filter out of the katadyn befree filter unit without using hydrapak seeker bladders by using a 25mm (internal diameter) * 5mm thick o-ring.
I dont expect anyone will use it in this way (i.e as a small gravity filter to sit ontop of a bottle) BUT the same method could maybe be used with large capped bladders such as the MSR ones which to my knowlege use the same thread as nalgene wide mouth bottles (you would just modify a msr/nalgene cap)
Just Carefully cut a hole in the container or cap - the size is crucial you better check as you go along as you want it JUST big enough to get the filter threads through (test without the oring, you may have to twist and jiggle it but thats ok, you want the hole just big enough. Practise on scrap first trust me!). Make sure you remove any sharp lip from the oring side.
Then remove the filter cap, put the oring on and insert the filter. Screwing the cap on will compress the oring against the flat surface (it must be flat!!) to seal. In my case i screwed the beaker lid on and tried to blow through the dry filter but could feel the back pressure due to the trapped air so it was sealing (I could not get the sawyer inline adapter to seal probably due to dimensions or something, i didnt try to figure out why. I have yet to try the sawyer white push-pull cap).
I used a 600ml TATAY plastic beaker (high quality spanish tupperware brand). o-ring must be against a flat surface.
Nice thing about the befree filter is no backflushing, I can just put the lid on and shake well. Descaling it with hot vinegar/citric acid should also be easier due to the exposed hollow fibres.
In this application it is slow due to lack of water hieght in my 600ml beaker and measured 500ml in 5 mins.
I dont expect anyone will use it in this way (i.e as a small gravity filter to sit ontop of a bottle) BUT the same method could maybe be used with large capped bladders such as the MSR ones which to my knowlege use the same thread as nalgene wide mouth bottles (you would just modify a msr/nalgene cap)
Just Carefully cut a hole in the container or cap - the size is crucial you better check as you go along as you want it JUST big enough to get the filter threads through (test without the oring, you may have to twist and jiggle it but thats ok, you want the hole just big enough. Practise on scrap first trust me!). Make sure you remove any sharp lip from the oring side.
Then remove the filter cap, put the oring on and insert the filter. Screwing the cap on will compress the oring against the flat surface (it must be flat!!) to seal. In my case i screwed the beaker lid on and tried to blow through the dry filter but could feel the back pressure due to the trapped air so it was sealing (I could not get the sawyer inline adapter to seal probably due to dimensions or something, i didnt try to figure out why. I have yet to try the sawyer white push-pull cap).
I used a 600ml TATAY plastic beaker (high quality spanish tupperware brand). o-ring must be against a flat surface.
Nice thing about the befree filter is no backflushing, I can just put the lid on and shake well. Descaling it with hot vinegar/citric acid should also be easier due to the exposed hollow fibres.
In this application it is slow due to lack of water hieght in my 600ml beaker and measured 500ml in 5 mins.
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