square/rectangular scrubber?

spacemanspiff1974

I was staring at my aquarium wet/dry filter the other day and came up with a new scrubber idea, but I need to know if this is a bad idea.

The scrubber channel is axial but square or rectangular instead of round. I'm thinking a base of 5x5 or 6x6 and a height of 6 or 7". There is no center tube for exhaust air. All air comes up from the bottom, through the scrubber and out to the sensors, etc.

Would this shape decrease scrubber efficiency over a circular axial scrubber?

Marc T

Its not a bad idea, one of my friend is using that sort of scrubber in is home made ( mas depth 120 m ), works fine.
This scrubber comes from a "fireman" rebreather.
More details later if needed

msquito

I'm not sure if this would be an applicable comparison, but in working with mechanical engineers for building design I've come to understand that the most efficient sectional shape for ductwork tends to be circular. Aparently the corners are not very efficient at allowing air passage (maybe due to additional surface friction in the corners?) and ducts tend to be sized dimensionally similar (ala a 16" round or a 16" x 16" square) despite the cross-sectional area delta. All that said (and if my understanding proves to be correct) I'm not sure it is totally comparable due to the filter media within the scrubber forcing dirctional changes by the gas flow anyhow. I'd be interested in seeing how much color change one gets in the corners of a rectilinear scrubber section though - that might be a good clue as to how efficient the extra volume is...
Not sure if that contributes at all, but I thought I'd throw it out there.

spacemanspiff1974

I too was considering the effect that the Ca(OH)2 granules would have on the air flow. With constant redirection, I would think that a square scrubber would be less of an issue than what would be found in a typical air duct.

Janwillem Bech

Draeger already made a commercial model that was used at great depth.
Bailout system for deepdiving (200 mtr / 600 ft)

http://www.therebreathersite.nl/jan_jahn_sms_1.htm

Janwillem Bech
http://www.therebreathersite.nl

Andy M

Havnt you just described the Sport KISS scrubber? Granted it works slightly differently but it is two square scrubbers with a small channel between them. Why is this idea so different?

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onetime

I was going to post the same thing earlier. Sport Kiss seems to be pretty much a rectangular scrubber.

I think most scrubbers are cylindrical because it's more traditional and gives wider options when it comes to sealing (o-rings are easier to use in cylinders than boxes I'd think). Also, depending on the material, the cylinder shape would seem to offer more resistance to deformation under pressure.

Andy M

And its easier to make, simply being a glorified pipe that can be turned on a lathe.

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spacemanspiff1974

I completely forgot about the sport kiss. Banging my head on the table right now.

Thanks.

koputai

And if you look at the picture of the open scrubber on that page, you can see from the reaction marks on the mesh, that the active area is through the centre, with the sides near the walls comparatively clean. This would indicate, in this example at least, that the scrubber usage isn't optimum.

Cheers,
Jason.