[PSUBS-MAILIST] scrubber performance

Fri Feb 17 13:13:11 EST 2017

Rick,I have an old school aircraft altimeter, BUT most people are going with sky diving  altimeters and they even go so far as having stickers made to go on the face plate that indicates add or reduce O2.  Think Alec has the details on that.  Hank 

    On Friday, February 17, 2017 11:09 AM, Rick Patton via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Sounds good Hank. I agree the more redundancy the better when it comes to life support. Any specific type recommended? 
Rick 
On Fri, Feb 17, 2017 at 7:54 AM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Rick,An altimeter is still a good idea, I think anyways.  First it will let you know if you have an over or under  pressure and it will never let you down, like electronics can.  The altimeter will verify what your instruments are telling you.  If your altitude is going up then your pressure is dropping witch means you add O2 .  If your altitude is dropping then your pressure is increasing witch means you are either adding to much O2 or your scrubber is not keeping up.  Relying on just an altimeter in not good either because you can get pressure changes from temperature changes.  The sub will drop in temperature in  cold water when you sink, that will cause a drop in pressure witch has nothing to do with environmental control.  Hank 

    On Friday, February 17, 2017 10:37 AM, Rick Patton via Personal_Submersibles <personal_submersibles at psubs. org> wrote:

 If I have a good 02 and C02 sensor, should I still have an altimeter and how would I base the altimeter reading for adding 02? 
Rick
On Fri, Feb 17, 2017 at 5:43 AM, Sean T. Stevenson via Personal_Submersibles <personal_submersibles at psubs. org> wrote:

  I don't recall seeing insulation in the DW2000 either.  Perhaps Phil will chime in on this?  It is possible that being so compact, the surface area of the DW hull is small enough that the contained heat loads can keep up to the moisture production.  Also, those are certified through GL, and as such may have different requirements than ABS's 30% - 70% RH.  Can anyone speak to the GL rules on this?  I can't see avoiding a 100 % RH environment, and the consequent condensation, when submerged in 5°C water without either insulating or employing dessicants to remove the moisture.  Immediately next to the hull, it will always be colder, so you may get condensation on the hull despite being within humidity limits on the cabin air on average.  I was thinking that a cylindrical pressure hull would be relatively simple to insulate though, with something like AP Armaflex sheet material.  You wouldn't even necessarily need to apply at 100% coverage, but rather just enough to reduce the heat loss to meet the 70% RH limit at whatever your cabin temperature is. (14°C - 30°C are the recommended temperature limits, but that's not actually a rule under ABS UWVS). Insulating just the large cylindrical surfaces between frames might be sufficient.  In my own design, insulation is a necessity - otherwise I won't be able to keep my coffee hot.

 Sean

 On 2017-02-15 17:41, hank pronk via Personal_Submersibles wrote:

  Sean, I can not remember the temperature over the length of a typical dive.  I would estimate 10C after 1\2 hr at 100 feet.   When I dive Kootenay  lake it is probably 5C  I wonder how DW's manage, they dive all over the world and I am sure in the winter. Hank

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