[PSUBS-MAILIST] Electronics contents gauge

[Alan James via Personal_Submersibles]

Thanks Cliff,I am having 2 independent O2 systems & 2 air supply systems.Only low pressure air going in to the hull, with a cross over valvefor the ballast air. Also doing 3 or 4 days O2 supply. So althoughit wouldn't be ideal having a wrong pressure reading, it wouldn'tbe fatal. I like all that you are doing in that system & thanks for the details.BTY did you see the new LED I am playing around with?80W Flip chip that dissipates heat faster from the individual LEDs &is a round, smaller unit than normal. It will mean I can get away witha smaller lens; the lens being the most expensive part.Have just ordered 15 samples from the manufacturer (who makes theBridgelux) at $6.50 each.Alan 

      From: Cliff Redus via Personal_Submersibles <personal_submersibles at psubs.org>
 To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
 Sent: Tuesday, November 1, 2016 4:00 AM
 Subject: Re: [PSUBS-MAILIST] Electronics contents gauge
   
Alan, I agree 100% with Emile on this. Given the safety implications of not knowing the air pressure in external air tanks, this needs to be a rock solid measurement.  On my boat, for the HP air pressure, I use a 1/4 MNPT sensor with a 1-5 vdc analog output screwed into a 316L SS penetrator that has a 1/4 FNPT thread on the interior side and ANSI 7/16-20 UNF thread on the exterior.  I use a Swagelok fitting PN SS-400-1-OR that lands in the penetrator and uses a o-ring face seal.  This fitting converts to 1/4" tube which I use for all HP air line. 1/4NPT gage pressure sensors are always available on Ebay with either analog voltage output or analog current output. This sensor wires directly into PLC analog input module.  PLC ladder logic can then implement low pressure alarms and interlocks to prevent diving when air pressure is low or someone forgets to turn on HP air valve.
Cliff
On Sun, Oct 30, 2016 at 3:19 PM, emile via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

The scuba pressure sensors are wireless. Most scuba divers don’t want it as it is unreliable. Best would be to screw a industrial pressure sensor (with ¼ “thread or so) into the penetrator plate and attach a HP line on the outside.  Br, Emile Van: Personal_Submersibles [mailto:personal_submersibles- bounces at psubs.org] Namens Alan James via Personal_Submersibles
Verzonden: zondag 30 oktober 2016 21:02
Aan: Personal Submersibles General Discussion
Onderwerp: [PSUBS-MAILIST] Electronics contents gauge Is there a suitable electronic scuba tank contents gauge out there?I am after something that plugs in to the high pressure port of the1st stage regulator & has wires off it that I can run through a throughhull so I can display the tank contents pressure on a screen.Trying to avoid bringing high pressure in to the hull.An alternative may be to run a high pressure line to a throughhull & have an electronic pressure gauge threaded in to this from the inside of the hull. However with the second method, I wouldn't havea shut off valve if the pressure gauge failed some how.Alan
 
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