[PSUBS-MAILIST] co2 scrubber

Mon Feb 13 06:57:00 EST 2017

seems to be loads of 12v ones available as well.  Probably useless.

http://www.ebay.co.uk/itm/500ml-Portable-Mini-Air-Dehumidifier-Damp-Mould-Moisture-Home-Kitchen-Bedroom/131982930763?_trksid=p2045573.c100507.m3226&_trkparms=aid%3D555014%26algo%3DPL.DEFAULT%26ao%3D1%26asc%3D20151016114640%26meid%3D3e6e46fed99d49f39e6dd133cc4d3796%26pid%3D100507%26rk%3D1%26rkt%3D1%26

On 13 February 2017 at 11:49, James Frankland <jamesf at guernseysubmarine.com>
wrote:

> I wonder if something like this would work?  I have them to keep the boat
> dry in the winter and it scoops up loads of water. But not sure if it would
> work to reduce humidity quickly enough when diving.
>
> http://www.ebay.co.uk/itm/Damp-Rid-Hanging-Moisture-Absorber-3-Pack-FG83K-
> Moisture-Absorber-/160887533831
>
> On 13 February 2017 at 07:30, Alan via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>> Sean,
>> in this email you are advising keeping humidity between 30 & 70%.
>> Any ideas on the best way of doing that? I am going to use a humidity
>> sensor & PLC, so have the option of automating functions.
>>    Have thought of having some sought of valve that channels air through
>> a filter prior to the scrubber, when humidity is high.
>> Another thought was blowing air under a raised floor so that moisture
>> laden air was forced between the floor & hull, & condensed against the
>> cold hull.  I have thought about peltier coolers also, as they have the
>> dual
>> option of being heaters by reversing the current. They are a bit expensive
>> on power though.
>> Alan
>>
>> Sent from my iPad
>>
>> On 5/02/2017, at 2:31 PM, Sean T. Stevenson via Personal_Submersibles <
>> personal_submersibles at psubs.org> wrote:
>>
>> I am skeptical of the utility of the colour indicating absorbent. The
>> reaction front in an axial scrubber is unlikely to be planar (unless
>> perfectly diffused), but rather conical, so you could have breakthrough in
>> the center before the indicating edge approaches the end of the canister,
>> for example. I think actually measuring the CO2 accurately and using the
>> rise in level as the indicator of scrubber breakthrough is the better
>> course of action. One thing to note is that the colour change in the
>> indicating absorbent is usually subtle, and submarine interiors are usually
>> subdued light environments. In some media, the colour is readily apparent
>> immediately after reaction, but the colour fades when left to stand for
>> some time.  Also, even if you have an acrylic or polycarbonate canister,
>> dust from the scrubber media can accumulate on the inner wall and make
>> visual inspection difficult.
>>
>> If I were me, I'd be inclined to design a scrubber that would permit
>> relatively easy media or canister changes in situ, with a designed capacity
>> equal to the mission time + reserve time (or split between multiple
>> scrubbers), and then keep one or two additional sealed canisters or media
>> changes tucked away on board.  That way, you can make effective use of the
>> media by exhausting it right to breakthrough. If you make short dives, you
>> can do several on the same canister, and if you reach breakthrough
>> (arbitrarily set but below the permissible limit), you change it out. I
>> would choose a radial flow design, with airflow from outside to inside for
>> maximum efficiency, and consider addressing the operating humidity of the
>> sub to keep it between 30% and 70% RH.  Some moisture is actually required
>> for the scrubber to function, as the chemical reaction actually occurs in
>> aqueous solution on the surface of the media granules. I would definitely
>> make a point of ke! eping a partially used scrubber sealed off from
>> atmospheric air when not in use. In the absence of a sealed container,
>> simply keeping your hatch closed would suffice, as once the CO2 in the
>> cabin is all reacted it is inert. Atmospheric air has 400 ppm CO2 in it,
>> which will consume a scrubber over time if left exposed.
>>
>> Sean
>>
>>
>> On February 4, 2017 5:45:26 PM MST, Brian Cox via Personal_Submersibles <
>> personal_submersibles at psubs.org> wrote:
>>>
>>> I'd like to do a radial scrubber design but I also would like to use the
>>> indicating SodaSorb, so I can see the color change.  Being able to see the
>>> color change with a radial design would be a challenge !
>>>
>>> Brian
>>>
>>> --- personal_submersibles at psubs.org wrote:
>>>
>>> From: "Sean T. Stevenson via Personal_Submersibles" <
>>> personal_submersibles at psubs.org>
>>> To: Personal Submersibles General Discussion <
>>> personal_submersibles at psubs.org>
>>> Subject: Re: [PSUBS-MAILIST] co2 scrubber
>>> Date: Sat, 04 Feb 2017 14:53:27 -0700
>>>
>>> Yes. For the chemical reaction to work properly, the air needs some
>>> dwell time against the scrubber media. This may be specified in the media
>>> datasheets. Regardless, if your fan is too strong and you're blowing tons
>>> of air through it, you may just dry it out while scrubbing really
>>> inefficiently.  If you! slow it down, you give the CO2 time to react and
>>> the bed gets more efficient. This is one of the reasons why radial flow
>>> scrubbers have an advantage - the surface area is huge, so the actual flow
>>> velocity through the bed is minimal in comparison to an axial flow design.
>>> You only need enough airflow to remove CO2 faster than you produce it, and
>>> ideally to process the entire air volume in your cabin a few times an hour.
>>> Slow, large diameter fans will be more effective than a high speed but
>>> small fan, and probably easier on your batteries too.
>>>
>>> Sean
>>>
>>> On February 4, 2017 2:38:32 PM MST, Brian Cox via Personal_Submersibles <
>>> personal_submersibles at psubs.org> wrote:
>>>
>>> Is there such a thing as to TOO much air flow through a scrubber ??
>>>
>>>
>>> Brian
>>>
>>> --- personal_submersibles at psubs.org wrote:
>>>
>>> From: Cliff Redus via Personal_Submersibles <
>>> personal_submersibles at psubs.org>
>>> To: Personal Submersibles General Discussion <
>>> personal_submersibles at psubs.org>
>>> Subject: Re: [PSUBS-MAILIST] co2 scrubber
>>> Date: Fri, 3 Feb 2017 09:34:40 -0600
>>>
>>> Brian, see http://www.ntz-filter.com/Radial_Filtration_versus_Axial_
>>> Filtration for picture which is worth at least a hundred words.
>>>
>>> Cliff
>>>
>>>
>>>
>>> On Thu, Feb 2, 2017 at 11:36 PM, Brian Cox via Personal_Submersibles <
>>> personal_submersibles at psubs.org> wrote:
>>>
>>> What is the difference between a Axial scrubber and a radial ?
>>>
>>> Brian
>>>
>>> --- personal_submersibles at psubs.org wrote:
>>>
>>> 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
>>> Date: Thu, 2 Feb 2017 16:29:34 -0600
>>>
>>> Started life with axial scrubber but now use radial design.  Has !
>>> worked much better for me.
>>>
>>> Cliff
>>>
>>> Sent from my iPad
>>>
>>> On Feb 2, 2017, at 1:06 PM, hank pronk via Personal_Submersibles <
>>> personal_submersibles at psubs.org> wrote:
>>>
>>> Thanks' guys, that helps.
>>> Cliff, I assume you have an axial scrubber
>>> Hank
>>>
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