[PSUBS-MAILIST] Scrubber size

Mon Dec 14 11:07:21 EST 2020

 David, the scrubber on the R300 holds 3.5 lbs of SodaSorb HP.  The longest I have been submerged was 12.5 hours during a pool test.  The longest I have been submerged for a normal dive event is 5 hours at one of the Islamorada PSub conventions.  My NOP is to discard partially consumed absorbent at the start of each dive day regardless of how many hours used and refill.  I keep spare absorbent in sealed bags onboard sufficient to last 80 hours (8 hours normal dive time plus 72 hours emergency time).  Due to W.R. Grace, the manufacture of SodaSorb HP, stopping manufacturing of this CO2 absorbent, I have switched to DiveSorb Pro from Dragger.  I have no experience with the new absorbent but plan on doing some shop testing prior to my next dive.  If you are interested, I have a report on my life support system where I have documented the system as well as all testing.   If you are interest, I would be glad to send it to you if you will contact me off list.  The scrubber design I used is based on the scrubber in Snoopy.   It is a radial flow charcoal filter container with a blower that discharges the clean air from the top.  After I got the right blower speced for the unit, the scrubber has worked great.
The filter container is 6" OD x 7-1/2" height, with 4" ID for annulus that contain the absorbent.  The one I use is like iPower 4" 6" 8" 10" 12" Inch Air Carbon Filter Virgin Charcoal for Inline Fan | eBay

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iPower 4" 6" 8" 10" 12" Inch Air Carbon Filter Virgin Charcoal for Inlin...

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I am a big believer in shop life support tests so that you know the actual performance limits of your life support system.  I would encourage all phubbers to do this qualification work prior to normal dive operations.  It is actually a lot of fun to conduct these test.  I find there has been no problem in getting volunteers for these life support test which need to be done in a controlled environment for safety purposes.

    On Sunday, December 13, 2020, 09:14:10 PM CST, David Colombo via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

 Hi Guys, I was following Jon's thread and thought how appropriate.  I am building a scrubber for the VAST sub. The housing I acquired was a carbon filter used in the grow industry.  With an interior screen core for the air to flow thru to the sodasorb core to the outside screen. The volume of this space holds 3.6 lbs of carbon. Not sure if the weight per volume of the sodasorb is exactly the same, but if it is that chamber would produce about 14.4 hours of absorption. I'm am thinking that I am going to cut the unit in half. My thinking is that for a typical day of diving, 14 hrs seem a bit excessive and I would be wasting  a lot of sorb.  With pre packaged, vacuumed bags I can carry what would be required to meet ABS guidelines.  One of my concerns though is that with the compactness of the VAST sub with a reduced volume of sorb, would the heat generated be greater than with more sorb, thereby also increasing the humidity buildup.I am hoping to get some experience feedback from other small owners, and what they have used volume wise of the sorb for a typical day of diving. The co2 unit I am using measures humidity as well as co2 ppm. Attached are pictures of the unit ready to have the fan attached.Best Regards,David Colombo

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