[PSUBS-MAILIST] Bellows add

[Alan via Personal_Submersibles]

Hank,
the altimeter wouldn't help in the case of an air leak, as you could have the scenario
where the scrubber takes the C02 out of the air but instead of replacing with O2
from the bellows add, it is replaced with air from an air leak, & the cabin O2 content
would slowly diminish with the pressure staying the same (hope that makes sense).
To save space & cost & if you are the only person diving this sub, you could just have a needle valve & adjust the flow based on O2 readings.
Alan


> On 25/05/2020, at 8:08 AM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> 
> Alan,  I was thinking the same idea with the scuba regulator.  I rely on the altimeter and am a good habit of checking it.  Also I am like the canary in the mine.  I get real sore ears when the pressure changes in the sub.
> Hank
> 
> On Sunday, May 24, 2020, 1:24:32 PM MDT, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> 
> Hank,
> there is a flaw with the Bellows Add system that I can see, in that if you
> have an air leak that increases the cabin pressure then the Bellows Add
> system won't add O2. 
> Ultimately you are relying on your O2 sensor & even then O2 sensors
> have a large failure rate & a life expectancy.
> Rebreathers use 3-5 sensors for redundancy & compare signals.
> For a large sub you have a lot more time for any failure to have an effect
> than you would in a sub like your 1 person or Cliff's. 
> Maybe if you insist on a Bellows Add system, have an extra O2 sensor.
> The second stage regulator works the opposite way than what you want
> with the water pressure pushing on a thin diaphragm that has a lever the
> other side that opens the valve. Maybe if you glued the lever to the inside
> of the diaphragm you could open a valve with it. You would only use the 
> regulator valve though, as the rest would be useless.
> Better still, make a small sealed enclosure with a diaphragm on one face
> & attach the second stage lever mechanism to the outside against the diaphragm.
> That way you could make a screw in / out fine tuning adjuster as per DW.
> Alan
> 
> 
>> On 25/05/2020, at 1:50 AM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>> 
>> Hi All, I am looking for ideas on how to make a automatic O2 feed similar to the DW bellows add.  I want a non electronic system.  I was thinking about a scuba second stage regulator conversion, that senses negative pressure to release O2.  Sean???
>> Hank
>> _______________________________________________
>> Personal_Submersibles mailing list
>> Personal_Submersibles at psubs.org
>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
> 
> _______________________________________________
> Personal_Submersibles mailing list
> Personal_Submersibles at psubs.org
> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
> _______________________________________________
> Personal_Submersibles mailing list
> Personal_Submersibles at psubs.org
> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.whoweb.com/pipermail/personal_submersibles/attachments/20200525/0500b265/attachment-0001.html>