[PSUBS-MAILIST] Electronic contents gauge

[Alan James via Personal_Submersibles]

I just experimented with the flow from the high pressure porton my 1st stage regulator. That's the one your pressure gauge runs off.Even though the hole is literally a pin prick, I was getting at least2 liters a second flow out of it. I am building a similar sized sub to Cliff's R300 & a leak like that,apart from increasing the pressure massively, would be hazardousif it was O2. In 4 minutes I could have 70% O2 based on an airvolume in the sub of 250 liters.I think I'll go for a pressure gauge outside my view port or try pottinga digital pressure gauge & just send the wires through a penetrator.Alan

      From: Alan via Personal_Submersibles <personal_submersibles at psubs.org>
 To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
 Sent: Wednesday, November 2, 2016 12:41 AM
 Subject: Re: [PSUBS-MAILIST] Electronic contents gauge
   
Thanks for the advice Steve.I haven't looked in to the electronic oxygen add system too deeply.Bound to have some questions later on.Cheers Alan
Sent from my iPad
On 1/11/2016, at 9:39 pm, Stephen Fordyce via Personal_Submersibles <personal_submersibles at psubs.org> wrote:


Thanks Alan - I should probably point out that my Watchdogs are rather literally named - ie. they can sense something is wrong and do something simple about it, but are limited in how complex the reaction can be.  It can only handle one O2 input, and the control is limited by controller settings - it's an off-the-shelf item and not fully programmable like a PLC.  Good for an independent backup or alarm.  As a primary system it could be made to work but would require a thoughtful setup.
Eventually I do plan to make a rebreather controller (for the rebreather I'm designing) which would be perfect (many O2 cell inputs and a solenoid or two output), but that's a while away!
A key thing to consider in automatic oxygen adding is placement of sensors, natural mixing of the air and sufficient time delay in the control system to get meaningful feedback before the next oxygen injection (Ie. rebreather controllers squirt a little bit of oxygen in, wait a few seconds for it to mix, and then measure, and squirt in more accordingly).
Cheers,Steve
PS: I also have some M12 plated brass Blue Globe cable glands if you find yourself short a couple - very hard to get down here.


On Tue, Nov 1, 2016 at 2:19 PM, Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:


Steve,sending this again as I didn't receive it...Steve,I am wanting to build an O2 system like James Cameron had.An O2 valve that flows continuously with a top up from a solenoidvalve which  triggered by a plc that is receiving signals from 3 x O2 sensors. Mainly because I want to keep everything as small as possible.   With your O2 unit it looks like you could have it doing similar;turn on a solenoid to top up the O2 beyond what is flowing in froma pre-set valve. A bellows add system that replaces the bellows withyour "Oxygen Watchdog"Know what you mean about UK freight charges, have cancelled itemsbecause of ridiculous freight charges. Thanks for the offer of buyingthrough your firm.Cheers Alan
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