[PSUBS-MAILIST] CO2 scrubber

Fri Mar 22 22:49:10 EDT 2024

 Good to hear from you Hugh.  I like the idea of populating a PSubs scrubber parameter spreadsheet.  Some of the parameters that need to be included are:
Number of occupantsMass of CO2 absorbent in ScrubberRadial or Axial flow through absorbentScrubber dimensionsBlower head curveBlower currentBlower powerBlower voltageBlower efficiency at the design flowrateAbsorbent supplierAbsorbent part numberTurnover time (cabin volume /volumetricflow rate through scrubber)Absorption capacity (weight %)

As for testing, I am a big believer in shop dives while logging cabin environment (pressure, temperature, relative humidity, CO2 ppm and O2 %).Scrubber performance is a function of not only the pellet size but also RH and cabin temperature.  You can do a number of these life support test dives with different objectives like the scrubber's ability to meet ABS <5000 ppm rule, how long it takes to reach saturation of absorbent, and how long before you reach 5000 ppm if your blower is turned off.   You can also measure hotel electrical load to determine if your auxiliary battery can meet the ABS 72-hour rule.  I used these shop dives to fine-tune my life support system going through several different blowers until I found that worked the best for my boat. If you do these shop dives, an important safety requirement is of course to have someone monitor the test/occupant.
Cliff

    On Friday, March 22, 2024 at 05:34:39 PM CDT, via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

 Hi Cliff et al,
Many thanks for sharing your fan recommendation. I have googled Cliffs
blower and got the fan curve/data to compare it with mine.  The one I
selected is about double the power and as it is a computer forward curve
blower it can go up to 1" of water gauge.  Cliff's design appears to have
its best efficiency area around 1/4" water gauge with a max of about 1/2".
The one I have is for a 2 person sub but it is untested. What I mean is that
we do not know the performance of the soda lime bed.  I had a good look at
the design of the late Phil Nuyten, before designing mine and learned a bit
from that.  His design appears to be a short air travel of approx. 2-3"
depending on where to measure.  What is the dwell time for yours, Cliff?

I think that it is great that Jon is doing the design from scratch but in
order to do the project it would be great if we could do a spreadsheet for
comparison of the different designs.  Cliff, as usual, has included the
obvious and in this case I would like to review mine in relation to the
amount of power used for the duration of the ABS required 72 hrs.  I am
aiming for 96 hrs but happy for 72 hrs.

Jon, where can we download/upload a spreadsheet and drawings / photos etc
to assist the project?  One of the aspects is to determine what sphere size
is being used and then what resistance at various flow rates of air per sq
ft or per 100 mm square (100 sq cm) .  I am proposing testing using a flow
meter of CO2 into a chamber and the maintainable CO2 level achieved.  An
airtight box of 1-2 cu metres is a suggestion but ideally a tank of a known
volume.  Somewhere there is a recommendation of how many air changes/hour is
best.  I need to retrieve the data I used when designing mine but you guys
will be more current.
I am not a user of FB, Tiktok etc and try and confine my file transfer to
email attachments.  Cheers,  Hugh.

---Original Message-----
From: Personal_Submersibles <personal_submersibles-bounces at psubs.org> On
Behalf Of via Personal_Submersibles
Sent: Friday, March 22, 2024 1:56 AM
To: personal_submersibles at psubs.org
Subject: Personal_Submersibles Digest, Vol 127, Issue 31

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Today's Topics:

  1. Re: CO2 scrubber BOM or documentation (via Personal_Submersibles)
  2. Re: CO2 scrubber BOM or documentation
      (Cliff Redus via Personal_Submersibles)

----------------------------------------------------------------------

Message: 1
Date: Thu, 21 Mar 2024 11:02:09 +0100
From: via Personal_Submersibles <personal_submersibles at psubs.org>
To: "'Personal Submersibles General Discussion'"
    <personal_submersibles at psubs.org>
Subject: Re: [PSUBS-MAILIST] CO2 scrubber BOM or documentation
Message-ID: <026501da7b76$d67f5f40$837e1dc0$@airesearch.nl>
Content-Type: text/plain; charset="utf-8"

Hi Cliff, 

It is a Radial blower right? These ones create a higher pressure than axial
blowers. 

Br, Emile

Van: Personal_Submersibles <personal_submersibles-bounces at psubs.org> Namens
Cliff Redus via Personal_Submersibles
Verzonden: donderdag 21 maart 2024 00:17
Aan: Jon Wallace via Personal_Submersibles <personal_submersibles at psubs.org>
Onderwerp: Re: [PSUBS-MAILIST] CO2 scrubber BOM or documentation

Jon, see the attached drawing of the scrubber I will be using on the R400.
It is essentially the same configuration I use on the R300.  I have had good
luck with the Rapst RL90-18/24 Fan Blower.  These come up on eBay often.
You can get this used on eBay for $39 now.  These are good German-engineered
blowers that seem to strike a balance between adequate head, and not to much
current draw so that you can meet the 72-hour ABS rule and they are quiet.

System Papst RL90-18/24 Chassis Fan Blower | eBay

Cliff

On Wednesday, March 20, 2024 at 01:21:01 PM CDT, Jon Wallace via
Personal_Submersibles <personal_submersibles at psubs.org
<mailto:personal_submersibles at psubs.org> > wrote: 

Hey guys, I'm in the initial thought processes of CO2 scrubber design and
really don't want to reinvent the wheel on this component.  Are any of you
willing to share some details on your design?  I know Alec submitted a 3D
printer design which we have on the website however I don't have access to a
3D printer and frankly even though I've spent 40+ years in software
development and can modify a UNIX kernel, my CAD skills are pretty much
non-existent.

For this component I'd really like something that can be built with as many
off the shelf parts as possible.  Any suggestions?

Jon

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Message: 2
Date: Thu, 21 Mar 2024 12:55:47 +0000 (UTC)
From: Cliff Redus via Personal_Submersibles
    <personal_submersibles at psubs.org>
To: via Personal_Submersibles <personal_submersibles at psubs.org>
Subject: Re: [PSUBS-MAILIST] CO2 scrubber BOM or documentation
Message-ID: <1307222564.7713199.1711025747944 at mail.yahoo.com>
Content-Type: text/plain; charset="utf-8"

 Yes Emile, this is a radial blower. The direction of flow in axial intake
but radial centrifugal exhaust.??Some people refer to these as squirrel gage
blowers.?I was looking at my files and can't put my fingers on the datasheet
for this blower but see Papst RL90-18/14N which is a newer version of this
blower.??https://www.onlinecomponents.com/en/datasheet/rl901814n-12103307/
Cliff

    On Thursday, March 21, 2024 at 05:02:51 AM CDT, via
Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

Hi Cliff, 

 ?

It is a Radial blower right? These ones create a higher pressure than axial
blowers. 

 ?

Br, Emile

 ?

Van: Personal_Submersibles <personal_submersibles-bounces at psubs.org> Namens
Cliff Redus via Personal_Submersibles
Verzonden: donderdag 21 maart 2024 00:17
Aan: Jon Wallace via Personal_Submersibles <personal_submersibles at psubs.org>
Onderwerp: Re: [PSUBS-MAILIST] CO2 scrubber BOM or documentation

 ?

Jon, see the attached drawing of the scrubber I will be using on the R400.
It is essentially the same configuration I use on the R300.? I have had good
luck with the Rapst RL90-18/24 Fan Blower.? These come up on eBay often.?
You can get this used on eBay for $39 now.? These are good German-engineered
blowers that seem to strike a balance between adequate head, and not to much
current draw so that you can meet the 72-hour ABS rule and they are quiet.

 ?

System Papst RL90-18/24 Chassis Fan Blower | eBay

 ?

Cliff

 ?

 ?

On Wednesday, March 20, 2024 at 01:21:01 PM CDT, Jon Wallace via
Personal_Submersibles <personal_submersibles at psubs.org> wrote: 

 ?

 ?

Hey guys, I'm in the initial thought processes of CO2 scrubber design and
really don't want to reinvent the wheel on this component.? Are any of you
willing to share some details on your design?? I know Alec submitted a 3D
printer design which we have on the website however I don't have access to a
3D printer and frankly even though I've spent 40+ years in software
development and can modify a UNIX kernel, my CAD skills are pretty much
non-existent.

 ?

For this component I'd really like something that can be built with as many
off the shelf parts as possible.? Any suggestions?

 ?

Jon

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