[PSUBS-MAILIST] PLCs (was Commercial Grade O2 vs. Medical)

Wed Jan 3 21:56:56 EST 2018

Although I have worked with some Allen-Bradley type PLCs using ladder logic in the distant past, I work almost exclusively now with programmable automation controllers (PACs), which incorporate on-board field-programmable gate arrays (FPGA) on the same die as a CPU running a deterministic real-time operating system (e.g. National Instruments CompactRIO platform). These units are extremely versatile, although considerably more expensive than a PLC. The FPGA, main real-time OS program, and any PC / remote interface programs are all programmed with the same software suite, which while accessable to beginners, is unfortunately not a "master it in a weekend" type of deal - I have been developing for these for twenty years.

As for PLCs, I have been uninvolved for too long to give a useful recommendation. Defer to someone who has done more recent research / usage.

Sean

-------- Original Message --------
On Jan 3, 2018, 19:38, Alan via Personal_Submersibles wrote:

> Thanks Sean,
> good stuff, I feel more confident about using commercial O2 now.
> the ABS 23.5 % is quite restrictive. The problem is one rule fits all submarines.
> In a psub there is less that's likely to cause a fire than in a large deisel electric
> ( like Carsten's). The chances of you emptying the contents of your O2 tank
> & starting a fire at the same time are pretty slim.
> BTW have you come across the EZautomation Ezrack plc at all.
> http://www.ezautomation.net/ezrackplc/ezrackplc.htm
> I am looking seriously at it. It says it is fully American! Is that good or bad?
> Alan
>
> Sent from my iPad
>
> On 4/01/2018, at 2:58 PM, Sean T. Stevenson via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>> Per ABS, the inadvertent release of the contents of any single pressure vessel, if stored internally, must not raise the internal cabin pressure more than 1 atm (101.325 kPa) above the normal atmospheric pressure, nor raise the cabin air oxygen concentration above 23.5%. If an oxygen cylinder does not meet these requirements, it must be stored externally.
>>
>> So, you can get away with storing any amount internally, provided you use a greater number of smaller vessels.
>>
>> Sean
>>
>> -------- Original Message --------
>> On Jan 3, 2018, 18:15, Brian Cox via Personal_Submersibles < personal_submersibles at psubs.org> wrote:
>>
>>> Alan,        It's a long list !    What I need to do is make a check list of things I have wrong ;-)    and  then "things I have wrong but can maybe slide on"  !    One question, right of the bat,  with that O2 not being able to fill the cabin space more than one atmosphere,  I'm not understanding the terminology , how can it be possible to release a volume of air from a bottle WITHOUT raising the pressure above one atm if your are already at one atm ?
>>>
>>> I should go around my sub with a video camera inside and out and you could really get an idea of what I need !    For instance I know I need an additional ballast tank HP cylinder.
>>>
>>> Brian
>>>
>>> --- personal_submersibles at psubs.org wrote:
>>>
>>> From: Alan via Personal_Submersibles <personal_submersibles at psubs.org>
>>> To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
>>> Subject: Re: [PSUBS-MAILIST] Commercial Grade O2 vs. Medical
>>> Date: Thu, 4 Jan 2018 13:52:57 +1300
>>> Brian,
>>> fire away; there are a few people on psubs that are familiar with GL & or
>>> ABS.
>>> Alan
>>>
>>> Sent from my iPad
>>>
>>> On 4/01/2018, at 1:37 PM, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>>
>>>> Great info Alan !           BTW  I need to pick your brain on some of the Lloyd's or ABS regs or equivalent.
>>>>
>>>> Brian
>>>>
>>>> --- personal_submersibles at psubs.org wrote:
>>>>
>>>> From: Alan via Personal_Submersibles <personal_submersibles at psubs.org>
>>>> To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
>>>> Subject: Re: [PSUBS-MAILIST] Commercial Grade O2 vs. Medical
>>>> Date: Thu, 4 Jan 2018 13:22:59 +1300
>>>> Brian,
>>>> here is a link with some info.
>>>> https://www.padi.com/padi-courses/emergency-oxygen-provider
>>>> The best way about it is to enquire at your local dive shop as they will
>>>> probably run a course if they have a few interested people.
>>>> Alan
>>>>
>>>> Sent from my iPad
>>>>
>>>> On 4/01/2018, at 1:04 PM, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>>>
>>>>> Brian,
>>>>> I did an Emergency O2 providers course at a dive shop that sold O2.
>>>>> Now have a card with my face on it.
>>>>> I don't know if there are any regulations, but I get on well with the manager
>>>>> & this is what he was happy with me doing before he would fill O2.
>>>>> This was the easiest option, cheap & Only a couple of nights.
>>>>> I think if I went to any dive shop in the World & pulled out my Padi O2 card
>>>>> they would be happy to fill. Also we are carrying O2 so are able to provide it
>>>>> in a diving emergency, so thats an advantage to divers.
>>>>> Medical O2 providers may also be convinced to fill for you if you have the card.
>>>>> The other option for me was to do a mixed gas diving course which is much
>>>>> more expensive & intense.
>>>>> Cheers Alan
>>>>>
>>>>> Sent from my iPad
>>>>>
>>>>> On 4/01/2018, at 12:16 PM, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>>>>
>>>>>> Alan,           What's involved with getting a O2 cert for administering O2 ?
>>>>>>
>>>>>> Brian
>>>>>>
>>>>>> --- personal_submersibles at psubs.org wrote:
>>>>>>
>>>>>> From: Alan via Personal_Submersibles <personal_submersibles at psubs.org>
>>>>>> To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
>>>>>> Subject: Re: [PSUBS-MAILIST] Commercial Grade O2 vs. Medical
>>>>>> Date: Thu, 4 Jan 2018 11:21:46 +1300
>>>>>> Steve,
>>>>>> not the most experienced but this is what I'm doing.
>>>>>> I have 2 steel O2 cleaned tanks. ( 2 tanks as per GL for redundancy)
>>>>>> I have O2 cleaned scuba regulators & get my tanks filled at a dive shop.
>>>>>> Had to have an emergency O2 provider cert first.
>>>>>> I believe Nuytco were using composite tanks at one stage.
>>>>>> O2 tank options & fitting options here. (EMT medical)
>>>>>> http://www.emtmedicalco.com/OXYGEN-CYLINDERS-ALUMINUM-STEEL-COMPOSITE_c64.htm
>>>>>> You will need a tank fitting suitable for where you intend filling i.e. dive shop
>>>>>> or medical O2 supplier. Then you will need a compatible regulator . If you were
>>>>>> heading across country for a few dives maybe have interchangeable fittings or
>>>>>> spare tanks with different fittings if you need to switch between medical & dive
>>>>>> suppliers. ( I haven't heard this discussed before)
>>>>>> I have heard people say that medical & commercial O2 tank swap people don't
>>>>>> like the idea of their tanks going under the water. They also may require some
>>>>>> sort of certificate from you before they fill.
>>>>>> Have read of deaths from people using commercial rather than medical O2, but
>>>>>> this would be 100% O2 inhaled straight in to the lungs.
>>>>>> Phil offered to sell his O2 add system to Psubbers.
>>>>>> I am using a paediatric flow meter set at a minimal flow & are topping up via
>>>>>> 3 x O2 sensors wired to my PLC & operating a solenoid valve on the low pressure
>>>>>> O2 line. The PLC will be comparing the 3 readings & going with the average of
>>>>>> the 2 readings closest to each other. The PLC will notify me when the range of
>>>>>> one O2 sensor is out relative to the other 2 or the reading of the nearest 2 differ
>>>>>> by a certain amount & may need replacing. I think the life of a sensor is only
>>>>>> a year or so depending on the heat it is stored at. Being a small one person sub
>>>>>> I need to be a lot more careful as the O2 % can change a lot more quickly.
>>>>>> Cheers Alan
>>>>>>
>>>>>> Sent from my iPad
>>>>>>
>>>>>> On 4/01/2018, at 7:10 AM, Steve McQueen via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>>>>>
>>>>>>> I tried to search the archives but it wasn't very friendly.  Sorry to again ask about something I know has probably been discussed.
>>>>>>>
>>>>>>> I wanted to double ck. my O2 strategy.  After some investigation it seems I will buy a new steel high pressure oxygen tank for external mounting. My plan is to have it refilled with "commercial grade" O2 vs. medical grade 02.  As long as I keep my "personal" tank and not allow the filler to swap tanks I should create a "chain of custody" that will help me feel good about not having contamination.
>>>>>>>
>>>>>>> I am wondering how others are managing.
>>>>>>>
>>>>>>> Thanks,
>>>>>>> Steve
>>>>>>> _______________________________________________
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>>>>>>
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>>>>>
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