[PSUBS-MAILIST] O2 tanks

Sun Jul 2 13:09:26 EDT 2017

Sorry fat fingers on sensitive ipad, fired email too soon.
Also in the equation may be being towed; where noise from boat motors
& distractions, plus glare on the screen may hinder any warnings from being observed.
   The fact that you can die without warning from scrubbing out the C02 while 
neglecting to turn on the O2, has me worried. I believe that is why Kiteridge designed
the K250 without a life support system.
   You could design the electronics so that the O2 system wouldn't fail if the seat
switch failed while diving. Have a switch activated by the main ballast valves to
form another current path to the O2 add solenoid.
There would be two functions, the auto function where the solenoid automatically
adds air when the operator was seated & the hatch down; this normally is a top
up system but can supply all the required O2. The second function is turning
on the valve to the O2 flow meter. So there is a hull stop valve which remains open,
a tee to the solenoid add system & a valve on the O2 flow meter which is part of
the check list. Of course there would be normal low O2 warnings.
   Re the seat switch; I had a friend that always wanted a ride on mower. He bought
one when in the later stages of cancer & wasn't heavy enough to trigger the switch.
So light springs for light pilots.
Cheers Alan

Sent from my iPad

> On 3/07/2017, at 1:32 AM, Cliff Redus via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Alan, while you have the hatch interlock to protect from trying to dive the boat if hatch is open or if O2 and Air pressures are low, I would be a bit worried about a pilot weight switch tied to a solenoid on any part of the O2 supply (O2 supply interlock). This would be a NC solenoid valve so what happens if you loose power, your O2 to the boat would be offline if this valve was in the main supply line.  You would need a manual O2 override to be able to bypass this valve and have O2 makeup when all power  is off. 
> 
> With the intent of letting someone else pilot the one man boat, I think you can handle issues like O2 and air supply valve state by having a series of checklist the pilot performs with the surface coordinator .  If you have these checklist go through the PLC and HMI, then they can also act as interlock to prevent the novice pilot from diving the boat if any of these major systems are compromised.  On my boat, I have such a system.   
> 
> I kind of like the idea of the PLC knowing if a pilot is in the boat in addition to the hatch state but just not for O2 supply interlock. I need to chew on this pilot weight interlock idea to see what benefit it could bring my boat.
> 
> Best regards
> 
> Cliff 
> 
>> On Sun, Jul 2, 2017 at 12:47 AM, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>> Cliff, ( or anyone)
>> I was thinking of ways of making my one person sub idiot proof with 
>> regard to the turning on of the O2 supply. If I let anybody dive it I won't
>> be in there to oversee.
>> My ideas are to have a switch under the seat ( as they have on ride on lawn
>> mowers) & a hatch closure switch ( which is required by G.L. ) linked to
>> the O2 system so that when both switches are closed ( pilot seated &
>> hatch closed) the O2 feed system is activated. This will be the solenoid top
>> up part of the O2 system. A sign & maybe audible voice will say " Turn on Oxygen
>> valve". So the system will be like the DW O2 add system where there is a 
>> minimal amount of O2 constantly flowing but the balance flows in from a solenoid
>> valve activated by O2 level readings.
>> The CO2 scrubber could also be linked.
>> Any thoughts on this?
>> Thanks Alan
>> 
>>  
>> 
>> 
>> Sent from my iPad
>> 
>>> On 2/07/2017, at 1:13 PM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>> 
>>> Cliff,
>>> That is exactly what I did, I put the tank specs in the unstiffened cylinder program.  The only problem is, I can not findways of  the exact material the steel tanks are made from.  I am assuming same steel and gives a good estimate.
>>> Thanks Cliff
>>> Hank
>>> 
>>> 
>>> On Saturday, July 1, 2017 6:05 PM, via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>> 
>>> 
>>> Most of the FEA packages associated with 3-d modeling software use a linear model.  You would need an FEA tool that can model buckling to study this.  An alternative is to use the ABS stress analysis spreadsheet with no stiffeners.  This would give a conserative crush depth.
>>> 
>>> Cliff
>>> 
>>> 
>>> Cliff Redus
>>> 
>>>> On Jul 1, 2017, at 2:27 PM, Scott Waters via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>>> 
>>> 
>>> 
>>> I am unsure of the depth rating of an empty scuba tank. It could be easily found out on a solidworks simulation.
>>> Thanks,
>>> Scott
>>> 
>>> 
>>> 
>>> Sent from my U.S. Cellular® Smartphone
>>> 
>>> -------- Original message --------
>>> From: hank pronk via Personal_Submersibles <personal_submersibles at psubs.org>
>>> Date: 7/1/17 12:34 PM (GMT-05:00)
>>> To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
>>> Subject: Re: [PSUBS-MAILIST] O2 tanks
>>> 
>>> Thanks' Scott,Do you know what the max depth rating for an empty Scuba O2 tank is.  I suppose you could increase the rating by using only part of the volume and leave pressure inside them.  A sub could carry several in that case since they are close to neutral buoyant.  Hank 
>>> 
>>>     On Saturday, July 1, 2017 8:25 AM, Scott Waters via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>> 
>>> 
>>> Hank,Alvin has all the O2 supply internally. Pisces has the mission O2 internally and emergency supply externally in special steel cylinders that are pressure tested to 1.25 max depth while empty.Thanks,Scott Waters
>>> 
>>> 
>>> Sent from my U.S. Cellular® Smartphone
>>> -------- Original message --------From: hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> Date: 7/1/17 9:59 AM (GMT-05:00) To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> Su
>>>> 
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