<div dir="ltr"><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0in 0in 10pt"><font color="#000000" face="Calibri" size="3"><font color="#000000" face="Calibri" size="3">How an engineer controls the Oxygen level in a Psub</font></font></p><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0in 0in 10pt"><font face="Calibri"><font size="3"><font color="#000000">Take HP O2 (2200 psig max) stored in external tank/tanks and
bring this thru the hull using ¼” tubing and have a hull isolation valve on the
inside of the hull.<span> </span></font></font><font color="#000000" size="3">Bring the HP O2 into
a box using Swagelok fittings.</font><span><font color="#000000" size="3"> </font></span><font color="#000000" size="3">In the
box , use a pressure reducing regulator to drop the pressure to 5-10 </font><span><font color="#000000" size="3"> </font></span><font color="#000000" size="3">psig.</font><span><font color="#000000" size="3"> </font></span><font color="#000000" size="3">Feed
this reduced pressure O2 into a </font><span><font color="#000000" size="3"> </font></span><font color="#000000" size="3">0-10
SLPM O2 combination mass controller /meter that you source from ebay.</font><span><font color="#000000" size="3"> </font></span><font color="#000000" size="3">Control the O2mass rate </font><span><font color="#000000" size="3"> </font></span><font color="#000000" size="3">into the boat by sending a 0-5 VDC control signal
from either a potentiometer off a 5VDC regulated power supply or a PLC analog voltage
output card. </font><span><font color="#000000" size="3"> </font></span><font color="#000000" size="3">Put a Swagelok Vernier
needle valve (</font><span style="line-height:115%"><font color="#000000" size="3">SS-SS4-VH) in a bypass around the </font></span><font color="#000000" size="3">O2 mass
controller for manual control in the event you loose power.</font><span><font color="#000000" size="3"> </font></span><font color="#000000" size="3">Put a 0-3000 psig O2 pressure sensor to
measure the pressure of the HP O2 on the tubing as it enters the box.</font><span><font color="#000000" size="3"> </font></span><font color="#000000" size="3">Read the mass rate output signal (0-5VDC) of
the O2 in SLPM from the combination mass controller /meter.</font><span><font color="#000000" size="3"> </font></span><font color="#000000" size="3">Display this on a analog gage or PLC HMI. </font><span><font color="#000000" size="3"> </font></span><font color="#000000" size="3">Put the mass controller input signal under the
control of a PID loop with the set point being 20.95 mole percent O2.</font><span><font color="#000000" size="3"> </font></span><font color="#000000" size="3">Measure the mole percent of O2 in the cabin
as the process variable.</font><span><font color="#000000" size="3"> </font></span><font color="#000000" size="3">Use an inexpensive
plastic variable area meter (0-5 SLPM) on the LP O2 discharge as a backup
sensor in case you loose power.</font><span><font color="#000000" size="3"> </font></span><font color="#000000" size="3">This
system will hold the O2 mole percent constant in the boat regardless of the
size of the pilot or his/her O2 consumption rate and regardless of the cabin pressure
and temperature in the boat.</font><span><font color="#000000" size="3"> </font></span><font color="#000000" size="3">Lock out
the PID loop if the hatch switch is open.</font><span><font color="#000000" size="3">
</font></span><font color="#000000" size="3">Set up alarms for high and low O2 levels as per ABS.</font><span><font color="#000000" size="3"> </font></span><font color="#000000" size="3">Set up alarm for low O2 tank pressure.</font><span><font color="#000000" size="3"> </font></span><font color="#000000" size="3">In the same box install cabin pressure and
temperature sensors, a relative humidity sensor, as well as O2 and CO2 mole
percent sensors.</font><span><font color="#000000" size="3"> </font></span><font color="#000000" size="3">After installing this
box in your boat, do extensive shop dives by</font><span><font color="#000000" size="3">
</font></span><font color="#000000" size="3">getting someone to volunteer to be the guinea pig with the hatch closed
and data log the sensors from the box over a extend period of time say 10
hours.</font><span><font color="#000000" size="3"> </font></span><font color="#000000" size="3">Tune the PID controller as needed
until O2 level remains relatively constant. </font></font></p><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0in 0in 10pt"><font face="Calibri"><font color="#000000" size="3">To improve system,
add redundant sensors and add PLC ladder logic to detect bad sensors.</font><span><font color="#000000" size="3"> </font></span><font color="#000000" size="3">Can also improve system by measuring the O2
mole percent in the inlet O2 gas stream to make sure it pure O2 and not Argon
or some other gas.</font></font></p><font color="#000000" face="Times New Roman" size="3">
</font><p style="margin:0in 0in 10pt"><font color="#000000" face="Calibri" size="3">How non engineer controls the Oxygen level in a Psub</font></p><font color="#000000" face="Times New Roman" size="3">
</font><div style="margin:0in 0in 10pt"><font face="Calibri"><font size="3"><font color="#000000">When you feel light headed, surface, blow MBT and open hatch.<span> </span></font></font><font color="#000000" size="3">After head clears, close hatch and resume
dive.</font></font></div><div style="margin:0in 0in 10pt"><font color="#000000" face="Calibri" size="3"><br></font></div><div style="margin:0in 0in 10pt"><font color="#000000" face="Calibri" size="3">Cliff</font></div><font color="#000000" face="Times New Roman" size="3">
</font></div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Mar 13, 2018 at 8:08 PM, Brian Cox via Personal_Submersibles <span dir="ltr"><<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="font-family:Arial,sans-serif;font-size:10pt"><div>Alan,</div><div> I would eventually like to do that bellows add system but I'm not sure where I would get the tilt valve part of the system. Could that be had from scuba mouth piece parts ?</div><div> </div><div>Brian</div><div> </div><div><br><br>--- <a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.<wbr>org</a> wrote:<br><br>From: Alan via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.<wbr>org</a>><br>To: Personal Submersibles General Discussion <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.<wbr>org</a>><br>Subject: Re: [PSUBS-MAILIST] flow meters<br>Date: Wed, 14 Mar 2018 12:57:14 +1300<br><br></div><div>Brian,</div><div>I can't see what it's maximum inlet pressure is, but on another site it is</div><div>saying they are calibrated for an inlet pressure of 50psi. So would need</div><div>a regulator set to output 50psi & be rated for the inlet pressure you want.</div><div>I think those paediatric regulators have a 50psi output pressure so it </div><div>should work putting it in line with your flow meter but it is a bit of a strange</div><div>set up. I would have just gone with a normal regulator. See if you can</div><div>find out more info on your flow regulator model.</div><div>If you have a needle valve before your regulators to bypass them you can </div><div>just turn that on & off if all else failed.</div><div>Alan</div><div><br><br>Sent from my iPad</div><div><br>On 14/03/2018, at 11:43 AM, Brian Cox via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.<wbr>org</a>> wrote:<br><br></div><blockquote><div><div style="font-family:Arial,sans-serif;font-size:10pt"><div>Alan, </div><div> My plan was to go from my med regulator to my flow meter, My flow meter ( recommended from Cliff) has a range between 0 and 5 lpm. But I'm not really sure what the supply pressure for my flow meter is suppose to be. My O2 bottle is still sitting down at the dive shop , so as soon as I get it I'm going to test things out.</div><div> </div><div>Brian</div><div> </div><div><br><br>--- <a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.<wbr>org</a> wrote:<br><br>From: Alan via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.<wbr>org</a>><br>To: Personal Submersibles General Discussion <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.<wbr>org</a>><br>Subject: Re: [PSUBS-MAILIST] flow meters<br>Date: Wed, 14 Mar 2018 11:24:00 +1300<br><br></div><div><span></span></div><div><div>Brian, Rick,</div><div>GL is saying O2 consumption is 15 l/h resting, 40 l/h working & 26 l/h average.</div>(.43 litres per minute. ) Even my paediatric click regulator isn't fine enough by the<div>look of it, it does 1/4 of a litre, (.25) then the next step is 1/2 (.5) <div> You have got me rethinking this Rick. I might go with a flow meter so I can</div><div>finely adjust it & stop a potentially noisy O2 add system turning on & off</div><div>frequently.</div><div>Brian your 0-8 litre regulator seems to have the same increments in the low</div><div>range as my 0-4 litre regulator so you aren't loosing anything with it.</div><div>Alan<br><br><div>Sent from my iPad</div></div><div><br>On 14/03/2018, at 10:07 AM, Brian Cox via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.<wbr>org</a>> wrote:<br><br></div><blockquote><div><div style="font-family:Arial,sans-serif;font-size:10pt"><div>My medical O2 regulator goes from 0 to 8 lpm , My scuba shop finally got my bottle filled ! They had lost a transitional fitting needed to fill the bottle so I've been waiting for about two weeks now. It's a good thing they got the part because there is literally no other place around who will fill it ! Don't ask me how or why they are so easy about filling the O2 but I checked every other dive shop within 100 miles and nobody would do it. Believe me I'm not asking any questions, just thanking them for my fill ;-) </div><div> </div><div>Brian</div><div> </div><div><br><br>--- <a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.<wbr>org</a> wrote:<br><br>From: Rick Patton via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.<wbr>org</a>><br>To: Personal Submersibles General Discussion <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.<wbr>org</a>><br>Subject: Re: [PSUBS-MAILIST] flow meters<br>Date: Tue, 13 Mar 2018 10:39:44 -1000<br><br></div><div dir="ltr">Alan,<div><br></div><div>So you have the second one you listed so you are bringing the HP 02 right up to that?</div><div><br></div><div>Rick<br><div><br></div><div><br></div></div></div><div><br><div>On Tue, Mar 13, 2018 at 10:08 AM, Alan via Personal_Submersibles <span dir="ltr"><<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.<wbr>org</a>></span> wrote:<br><blockquote style="margin:0px 0px 0px 0.8ex;padding-left:1ex;border-left-color:rgb(204,204,204);border-left-width:1px;border-left-style:solid"><div dir="auto"><div>Rick,</div><div>just looked at my 0-4 LPM paedeatric click style oxygen meter & it says </div><div>"maximum pressure not to exceed 2600 psi."</div><span><div>Alan<br><br>Sent from my iPad</div></span><div><div><div><br>On 14/03/2018, at 8:13 AM, Alan via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.<wbr>org</a>> wrote:<br><br></div><blockquote><div><div>Rick,</div><div>as you say "above ambient" so at 350' depth you will have 130psi</div><div>coming out of the regulator plus another 175psi for the ambient depth.</div><div>EMT have this...<a href="https://www.emtmedicalco.com/GENTEC-OXYGEN-FLOWMETER-WITH-REGULATOR-0-15-LPM-CGA-870-OR-540-191M.htm" target="_blank">https://www.<wbr>emtmedicalco.com/GENTEC-<wbr>OXYGEN-FLOWMETER-WITH-<wbr>REGULATOR-0-15-LPM-CGA-870-OR-<wbr>540-191M.htm</a></div><div>I bought a pressure regulator for inside the hull to deal with that,</div><div>however the click style paediatric regulators they have take a high inlet pressure</div><div>although I can't see any literature on this at EMT.....</div><div><a href="https://www.emtmedicalco.com/PEDIATRIC-REGULATORS-0-4-LPM-CGA-870-8704.htm" target="_blank">https://www.emtmedicalco.com/<wbr>PEDIATRIC-REGULATORS-0-4-LPM-<wbr>CGA-870-8704.htm</a></div><div>Alan</div><div><br></div><div><br><div>Sent from my iPad</div></div><div><br>On 14/03/2018, at 6:53 AM, Rick Patton via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.<wbr>org</a>> wrote:<br><br></div><blockquote><div><div dir="ltr">Was looking into buying an 02 flow meter yesterday online and was told that the incoming pressure to the meter had a max incoming working pressure of 50 psi. My bottles will be on the outside and I have two 02 cleaned first stage regulators that will take them from HP to LP then into the sub.<div> I guess the average LP setting is around 150 psi + -above ambient? so I should be able to have a dive shop re set them down to 50 psi? What have others done that have the same scenario and wonder if there are flow meters that can take the 150 psi in?<div><br></div><div>Rick</div></div></div>
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