Radial scrubber design

DepthCharge

I’ve been thinking about building a radial scubber for a homebuilt. Here’s my question:
Looking at most designs, both scrubber inlet and scrubber outlet are at the top, or scrubber head. Does this cause uneven flow through the scrubber? Looking specifically at an in to out flow. It would seem that the side of the scrubber closest to the outlet would be used up first, allowing breakthrough on that side. Or is the difference negligible?

Would it be better to have the inlet enter the bottom, go up through the center tube, and exit through a port in the center of the scrubber head? Giving a more even flow.

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Later,
John

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Dave O

I always wondered about that.

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sunnyboy

No, the outlet of the scrubber is the entire external surface area. The port is merely a collection point for the gas back out the canister.

Cheers,

-S

Lake_Tahoe_Diver

Since I dive a Prism and that is the exact description of the flow thought the scrubber I can assure you it is used evenly from the inside out.

If I had to guess how come it comes out this way I would think it is because when breath you are not pushing all the gas to the inhale counter lung (ie pulling a vaccum). Some of the gas will stay in the exhale counter lung, some in the scrubber. Therefore you are not creating a strong vaccum that pulls the gas thought the scrubber from one side only. Instead it is a even slow flow though the entire scrubber.

That is my two cent worth. Do with it as you will. I am sure that others could explain it better than myself.

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sunnyboy

The center tube in a radial scrubber acts as a manifold to distribute gas to the scrubber bed. The outside of the scrubber (between scrubber bed and bucket wall) acts as a collection point for gas that has passed through the scrubber.

Compared to the resistance to gas flow created by the scrubber material, the resistance of the "clear air" space of the inlet tube and outlet (bucket) is negligible. Any measurable pressure drop between the top of the head and the bottom in these two areas would also be negligible. For all intents and purposes the gas flow through the scrubber at the top would be the same as the gas flow at the bottom. That is the beauty of the radial design.

-S

DepthCharge

Both explanations make sense. I didn't think about Lake_Tahoe_Diver's response, Did consider sunnyboy's, but wanted some confirmation.
Thanks

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Later,
John

It's better to beg forgiveness than ask permission