[PSUBS-MAILIST] scrubber performance

[Sean T. Stevenson via Personal_Submersibles]

Pay particular attention to ensuring that you can pack your scrubber in such a way as to eliminate the possibility of channelling. Gas will always flow through the least resistance path, and if the scrubber granules are not densely packed, your gas will flow through any voids in the media without being properly exposed to the surfaces of the media granules. Typically, diver rebreather scrubbers are filled in increments, with shaking / vibration mandated in between to settle the media to its most dense packing as you fill it, and finally a spring load or other adjustment maintains a zero clearance closure against the full scrubber.  Perhaps less important in a sub than a rebreather, as in the sub you are not directly rebreathing your exhaled gas at full concentration, but efficiency is important for other reasons, not the least of which is your power budget.

Sean


On August 15, 2016 8:12:28 AM MDT, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>I think I will use my re-breather scrubber from Gamma in Elementary
>3000 and make a new scrubber the way you describe for Gamma.  The
>re-breather scrubber works fine for one person.Hank 
>
>On Monday, August 15, 2016 7:54 AM, Sean T. Stevenson via
>Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
>
>Just to add to Cliff's comment, you will get the most even consumption
>of scrubber media in a radial scrubber when the flow is from the outer
>diameter to the inner diameter.  The flow velocity is slower at the
>greater diameter, so you want to expose the unscrubbed gas there first,
>so the CO2 concentration across the media lessens as the flow velocity
>increases at the inner diameter. Fortunately, this embodiment easily
>accommodates a squirrel cage fan drawing gas from an inner core.Sean
>
>On August 13, 2016 8:30:51 PM MDT, Cliff Redus via
>Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>Your scrubber meets ABS rules which requires the CO2 concentration to
>stay below 5000 ppm (1/2%) .  From my own experience, I found that the
>type of fan and the flow orientation makes a big difference in how low
>the scrubber can pull the CO2 concentration down to.  Specifically,
>squirrel cage blowers work better than axial fans and radial flow works
>better than axial  flow through the Sodasorb HP.
>I am proud of your mom.  
>Cliff
>
>
>On Sat, Aug 13, 2016 at 3:23 PM, hank pronk via Personal_Submersibles
><personal_submersibles at psubs.org> wrote:
>
>Hi All,I just did a two person life support test and the CO2 level sits
>around 4,000ppm  and the O2 flow is at .5 lpm   Is that CO2 level high?
>  When I am in the sub alone it sits around 2,500ppmI am getting Gamma
>all geared up for a big dive with my mother as the passenger, that
>means a ladder, comfy seat, hot coffee, cookies.  She is very
>excited!Hank
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