[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [PSUBS-MAILIST] heated sub

One other point here is that the flow rate itself is important for efficiency through Soda Sorb. The old Universal Labs scrubbers we used in most everything were essentially vacuum cleaner motors in a bomb proof container, and later study showed that they moved too MUCH air, and could have been more efficient for less electrical usage. Has anyone talked to Grace Chemicals about this specifically? Maybe they have something to offer. One thing they do have are preloaded cartridges used in hospitals. Expensive, relatively, but handy.
Vance


-----Original Message-----
From: Cliff Redus <cliffordredus@sbcglobal.net>
To: personal_submersibles@psubs.org
Sent: Mon, 16 Mar 2009 11:41 am
Subject: Re: [PSUBS-MAILIST] heated sub

Dan
 
I agree, the article on this home-built scrubber is good from a fabrication perspective but you need to step back one step and do calcs on the amount of absorbent required.  This unit was designed as part of a scuba re-breather unit.  What is different from a psub perspective is that most of the operation of the unit is done a much higher pressure than for a 1 atm boat.  I did a quick sizing calc using SodaSorb HP 4-8 mesh.  If you assume an 8 hour capa city for each cartridge, and you assumed the same OD and ID as in the article, (6" OD and 1.7" ID), the unit would only have to be about 4 inches long for a psub with one person.  As to pressure drop through this radial filter design, it will be low based on the testing that I did for my scrubber.  The real question in sizing the fan for circulating the cabin air through this filter is how much electrical current does the motor draw.  When I first built my scrubber I installed a fan that pulled to many amps.  While it did a great job circulating the air, the high current did not allow me to meet an ABS constraint of 72 hours on my emergency battery bank.  I then tried a small fan like you would see in a PC.  While this enabled me to run for 72 hours, the circulation rate was not quite adequate and I would get height CO2 level alarms.  I ended up finding a fan that was half way in between that met both constraints. 
 
Send me an email off list and I will send you my sizing calcs on the amount of absorbent required if you are interested.
 
Cliff

 

 

From: Dan H. <Jumachine@comcast.net>
To: personal_submersibles@psubs.org
Sent: Monday, March 16, 2009 7:33:37 AM
Subject: Re: [PSUBS-MAILIST] heated sub


Vance,
 
I agree,  That's a great article.  Not only a good design but I tip my hat to the guy for all his effort in documenting it as he did.  There's more work in the article then building the thing.
 
I want to build one also but my first thought is, it might have to be modified to work with fan pressure.  Do you have a feel for how easy it would be to push air through the "Sorb" material with a fan?   Do you think that constructing it as he did will allow the pressure created by a fan to move sufficient air through it?  
 
It could be easily altered by increasing the outside diameter and also the inner screen diameter and thin out the wall of "Sorb" the fan would have to push air through. 
=0 D
 
It's something I've wanted to add to my sub for a while, but just haven't done.  It's time I did. 
Building it would be easy but I don't know much about the "Srob" stuff that goes in it. 
 
Dan H.
----- Original Message -----
Sent: Monday, March 16, 2009 6:46 AM
Subject: Re: [PSUBS-MAILIST] heated sub


Alan,

I got on too, finally, and you're right. Great article, Nomdae. I'll be having one of those in my K350, thank you. Let me see, where did I put that chunk of one inch PVC?

Vance


-----Original Message-----
From: ALAN JAMES <alanjames@xtra.co.nz>
To: personal_submersibles@psubs.org
Sent: Sun, 15 Mar 2009 4:38 pm
Subject: Re: [PSUBS-MAILIST] heated sub

Nomdae,
That's a great article on making a scrubber. I got through on the link 1st shot.
It's the type of article we should be borrowing and putting permanently on the psub sight.
Can we do that Jon?
Alan
----- Original Message -----
S ent: Monday, March 16, 2009 1:43 AM
Subject: RE: [PSUBS-MAILIST] heated sub

Hey Frank:

I posted this link a few months ago, but I'll post it again because it sounds like this is what you're planning:

http://www.rebreatherworld.com/megalodon-rebreather-articles/7286-homebuilt-meg-radial-scrubber.html

It's a homebuilt CO2 scrubber. I'm wondering if someone could also fill it with "Damp Rid", or some other kind of desiccant, to help control moisture. It would be interesting to have a system that passed cabin-air through the drying canister, then through the CO2 scrubber, then injected O2 before blowing it over the viewports to keep them clear.

As for my heating/cooling needs, I'm not going to worry about it.  My sub will be a dark color (brown), and I'll be running it in water that'll be about 72 degrees average. If, after a few dives, I find myself sweltering or shivering, I'll think up something to fix the problem..

From: ShellyDalg@aol.com
Date: Sun, 15 Mar 2009 00:16:33 -0400
Subject: Re: [PSUBS-MAILIST] heated sub
To: personal_submersibles@psubs.org

Hi Dean. Ya, I'll need the heaters when20I come up to play "you sunk my battleship" with you.
Lake Superior IS cold. I grew up on Lake Ontario and I remember when we'd get ice flows coming off the lake. It would pile up 20 feet or better on the beach. Fun for kids playing in the ice caves and stuff. Scary when I think how stupid we were, but hey, it was lots of fun.
For heaters....well, that's a tough one. I'm very miserly with my electrical usage. I've been leaning toward a chemical solution rather than some kind of electrical resistance heater. My thought was that it'll be necessary to change out the air scrubber chemicals anyway, and a canister type thing with the scrubber chemical and another with a heater canister should be able to be incorporated into a "quick change" chamber with a small 12 volt fan. The outlet would blow clean, dry, warm air over the windows to ventilate the sub. The device will need a small condensate reservoir or trap, which would need emptying after a dive, and of course replacement of the scrubber canister and heater canister.
The trick is to make the canisters reuseable so you could carry a couple of sets, and just change the raw chemicals in the spares each day. Self heating chemicals are easy to get, and a finned two chamber canister, where the air flows over the fins, should be fairly easy to make. Pack the stuff in there, shake it up, put it into the fan unit, and warm air comes out.
My buddy has a little can thing he puts in his pocket when we ride on cold nights. He puts his hand in there and it warms right up. Good for about three hours. Seems like a larger unit with a fan could do the same thing. Haven't got that far yet, but I'm thinkin.......
Frank D.
 
Hotmail® is up to 70% faster. Now good news travels really fast. Find out more.