Re: [PSUBS-MAILIST] Snoopy life support test

["Sean T. Stevenson" <cast55@telus.net>]

OK - thanks.  I had another look at that thread, and the only other 
thing I would add is that you want uniform flow through the scrubber 
bed, so in the case of a radial flow scrubber where flow is from outer 
to inner diameter, while you need the fan to generate the pressure head 
& air flow consistently in the presence of resistance, you want the air 
flow at the fan exit to be as diffuse as possible, such that the flow 
across the scrubber bed is predominately the result of the pressure 
difference, as opposed to the air velocity at the fan exit.  For 
example, a fan with a small outlet on one side only of the canister with 
no additional mechanical diffusion may unevenly consume scrubber media. 
Avoiding this ensures that you get the same air flow over the whole 
length and therefore meet the design dwell time within the bed, or more 
importantly, that the scrubber media is exhausted evenly throughout the 
bed.  A good design check would be to use the purple-indicating media, 
and checking at the end of the dive if the extent of colour change is 
consistent from top to bottom of the canister.  In any case, for a given 
design volume flow rate, you want to minimize the velocity through the 
scrubber bed for maximum dwell time.

-Sean


On 09/08/2011 8:08 PM, Jon Wallace wrote:
> Date was 3/14/2011
> Subject was "open source scrubber design"
>
>
> On 8/9/2011 10:49 PM, Sean T. Stevenson wrote:
> > Alec - what was the subject and/or date of the message you quote?  
> > I'm trying
> > to find it so I can put it in context and perhaps comment further, 
> > but I'm
> > drawing a blank.
> >
> > -Sean



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