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Re: [PSUBS-MAILIST] CO2 Scubber Design Guidelines
When water touches Lithium I think it makes Lithium Hydroxide and hydrogen gas
(which is very bad). But aren't these things already Lithium Hydroxide? What
chemical do they turn in to when they get wet?
Alex
On 09-Feb-2010 Jo Bain wrote:
> Hi,
> as a rebreather diver using Sodasorb -a lot of it! I would recomend using it
> in place of Lithium hydroxide, if Sodasorb gets wet there's a decrease in
> performance but that's it. Lithium goes BANG especially when saltwater
> contacts it...that's why tech divers use Sodasorb even though Lithium is more
> effective at removing CO2....
> just my $0,02 worth
>
> Jo Bain
> ----- Original Message -----
> From: Greg Cottrell
> To: personal_submersibles@psubs.org
> Sent: Wednesday, February 10, 2010 5:56 AM
> Subject: RE: [PSUBS-MAILIST] CO2 Scubber Design Guidelines
>
>
> If anyone is interested- Extend Air offers Co2 absorbing curtains that
> would work without the need for a fan or electricity. Each box of curtains
> would keep one person alive for about 30 hours.
>
>
>
> http://www.extendair.com/MineSafety-07.pdf
>
>
>
> Greg C
>
>
>
>
>
>
> ------------------------------------------------------------------------------
>
> From: owner-personal_submersibles@psubs.org
> [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Cliff Redus
> Sent: Monday, February 08, 2010 7:42 PM
> To: personal_submersibles@psubs.org
> Subject: Re: [PSUBS-MAILIST] CO2 Scubber Design Guidelines
>
>
>
> Greg
>
>
>
> The link is interesting. It seems to be using the zeolite sieve not just
> for separation of the gas phases but also an absorption of the CO2 and latter
> reclamation with heat. I still think this technology is a bit of a stretch
> for a psub.
>
>
> Cliff
>
> Subject: RE: [PSUBS-MAILIST] CO2 Scubber Design Guidelines
>
> Cliff, Check this out:
>
>
>
> http://people.oregonstate.edu/~atwaterj/zeolite.htm
>
>
>
>
>
>
>
>
>
>
> ------------------------------------------------------------------------------
>
> From: owner- personal_submersibles@psubs.org [mailto:owner-
> personal_submersibles@psubs.org ] On Behalf Of Cliff Redus
> Sent: Monday, February 08, 2010 2:00 PM
> To: personal_submersibles@psubs.org
> Subject: Re: [PSUBS-MAILIST] CO2 Scubber Design Guidelines
>
>
>
> Greg
>
>
>
> A molecular sieve separates the CO2 gas stream from the O2 and N2 gas
> stream by forcing the air mixture through an engineered media ( zeolite )
> that is sized to allow the larger O2 (3.5 angstroms) and Nitrogen (3.6
> angstroms) molecules to pass and blocks the smaller CO2 molecules (3.3
> angstroms) from passing. So now that you have a slip stream of pure CO2 you
> have to do something with this like compress the CO2 and purge the gas out of
> the hull for figure out something else to do with this concentrated CO2
> stream. I personally think it is to complicated for a psub and breaks the
> KISS rule. It is a better fit for a large nuclear boat.
>
>
>
> Cliff
>
>
>
>
> Cliff Redus
> Redus Engineering
> USA Office: 830-663-6445
> USA mobile: 830-931-1280
> cliffordredus@sbcglobal.com
>
>
>
>
>
>
> ------------------------------------------------------------------------------
>
> From: Greg Cottrell <greg@precisionplastics.com>
> To: personal_submersibles@psubs.org
> Sent: Mon, February 8, 2010 12:10:21 PM
> Subject: RE: [PSUBS-MAILIST] CO2 Scubber Design Guidelines
>
> Hi Cliff,
>
>
>
> What do you think about using molecular sieve for CO2 removal?
>
>
>
> Greg C
>
>
>
>
> ------------------------------------------------------------------------------
>
> From: owner- personal_submersibles@psubs.org [mailto:owner-
> personal_submersibles@psubs.org ] On Behalf Of Cliff Redus
> Sent: Monday, February 08, 2010 10:48 AM
> To: personal_submersibles@psubs.org
> Subject: Re: [PSUBS-MAILIST] CO2 Scubber Design Guidelines
>
>
>
> The easiest way to build a CO2 scrubber is to buy some SodaSorb HP (4/8
> mesh) and use 2.2 lbs of this absorbent for every 8 hours per person in the
> boat. You pack enough of this absorbent for your normal dive into canister or
> any container with a fan and your good to go. If you follow ABS rules, you
> carry some reserve absorbent to give you an additional 72 hours of bottom
> time. For ABS rules this this means for say and 8 hour dive time plus the 72
> hours reserve, you would need about 22 lbs of Sodasorb HP. As a check, the
> Deepwork 2000 carries 24 lbs of this absorbent.
>
>
>
> The 2.2 lbs for 8 hours comes from
> http://www.sodasorb.com/English/downloads/Sodasorb_Manual.pdf, page 16 in
> which is says "In a properly packed and well designed canister... for 8-hour
> capacity... a canister should hold approximately 1 kilogram of (2.2 pounds)
> of SodaSorb absorbent".
>
>
>
> On my boat, I picked a canister size to meet my normal mission time and
> then played around with different fan motors until I found a fan size that
> would circulate the cabin air through the canister without pulling so much
> current that it would drain my emergency battery bank before I reached the 72
> hours limit.
>
>
>
> While this worked fine, I wondered about what a "properly packed and well
> designed canister" meant. I recently came across an excellent technical
> report that goes into a lot more detail on this subject. It is titled
> "Design Guidelines for Carbon Dioxide Scrubbers", (May 1983, revised July
> 1985) by M.L. Nuckols, A. Purer and G.A. Deason of the Naval Systems Center ,
> Panama city Florida .
> http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA160181&Location=U2&doc=GetTRDoc.pdf
>
>
>
> This goes into the impact of design variables such as temperature,
> pressure, canister length and diameter, relative humidity, CO2 concentration,
> flow rate through the canister and particle size. The experimental work
> sited in the paper is for SodaSorb. While this report was written for
> designing re-breather canisters operating at elevated pressures that a diver
> would see, it does handle the limiting condition of 1 atm that we would see
> in a 1-atm. psub.
>
>
>
> So if you need a little "light" reading while your doing your business in
> the morning, you might want to have a read. Now if we could just get someone
> to drop this into an excel spreadsheet, we would be in business.
>
>
>
>
>
> Cliff
--
Mailed with XFmail on 09-Feb-2010.
God saved Noah, but Noah had to build an ark!
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