US Source for Rosahl electronic dehumidifiers?

Does anyone have a US-based source for these parts? I’d love to do a better job of keeping filament dry. These look interesting. But cross-the-ocean shipping for onesies is often discouraging.

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Not sure which one you are referring to but here is a quick Amazon Search

Sorry, no. This is a very different design from anything on Amazon. It’s a very specific part. It basically actively moves humidity from one side to the other, and so would be installed in the side of a dry box and then you would never need chemical drying agents or silica gel.

Not Rosahl. But they do have membraine dehumidifers. Permselect located in Michigan

Thanks! It looks like those are gas-driven, either positive gas supply or vacuum, whereas Rosahl have electrically-driven membrane dehumidifiers. Electric membrane dehumidifiers seem to me probably a better choice for a hobbyist.

[Edit: fixed the topic description to be clearer…]

That’s actually a pretty nifty bit of tech. They are using electrolysis to break down the water and transporting the resulting hydrogen ions across the membrane, sort of like a fuel cell, and then reducing the H+ ions back to water with atmospheric O2.


@mcdanlj -
Did you continue this exploration / project? I’m looking to build a dry cabinet of my own for my filament. I’m printing more HTPET, and it’s time and energy intensive to periodically dehydrate it in the dehydrator. A few friends purchased cyclically recharged dryboxes, but I too am interested in building out a Rosahl membrane box. Curious if you ever found a US source for the membrane. Thanks!

I never did. I just recently purchased and have not yet deployed molecular sieve dessicant to replace silica gel, at least as an experiment.

I wish I had, though!

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Well, now I know how much it would cost. Now that I have 8 storage dry boxes, that would be over $1K!

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As an aside; I get my silica gel from the pet supplies store.
It’s sold as a absorbent kitty litter at good prices, my cats hate it, ymmv.I use a very fine linen bag for it since the (silica!) dust is an issue with the big bulk bags sold for this.

I made a cereal storage box based filament drybox with the smaller RS1 membrane from Rosahl. Works pretty well for keeping new (fresh unpacked) spools or pre-dried spools (lying around for days/weeks before) at 15% rel. humidity (compared to 60% outside in my region). And consumes just 0.2W power at that level constantly. Made a bunch of 3D printed parts for it and it’s powered from USB. See on if interested: Printables

I also grabbed a larger M-3M1R membrane which currently keeps a 50l storage box with 15 spools at constantly 15% rel. humidity. Also made a 3D printed mounting cover with USB supply but that’s not yet on Printables. Will add soon.

Yes, these membranes are a bit costly but they are very, very efficient in the long term compared to regularly using some Sunlu filament dryer or even an oven to dry spools or recover desiccant. I use four of the RS1 based dryboxes with the filament types I use frequently which is still less than 1W of constant power.


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They ship to US, also heard people say that Rosahl will sell directly if you use their contact form.