[PSUBS-MAILIST] O2 regulator

Sat Jul 19 23:59:44 EDT 2014

Hi Cliff,
The graphs on your plc sound a great idea. Good way to monitor things.
With G.L. the accuracy you get on the 0-50,000ppm (5%) unit is fine.
They require an accuracy of + or - 0.001 bar CO2 partial pressure. That is 1000ppm.
   ABS does say 0.5% by volume limit, but it lets you go up to 1% during a scrubber change over,
& 1.5% for emergency life support situations.
I like the 0-50,000 unit for peace of mind, in case you did get in an emergency situation & the CO2
level went beyond 10,000ppm. On the pdf for the higher range units it says that the minimum operating
pressure is .950 - 40 bar. So I guess you would need to monitor the cabin pressure with alarms to ensure you didn't
go below the minimum it functioned at. I couldn't see any pressure operating range specified with your unit.
    I'm not sure where I'm at with the aluminum pressure hull idea. Gas bubbles formed in the casting process

are hard to control. G.L. doesn't like aluminum as a pressure vessel, & it's more subject to galvanic corrosion than
steel. Also if I wanted it hard anodized I would have to do it outside N.Z. as there are no tanks big enough here.
There are ASME rules for cast aluminum pressure vessels, but I haven't got hold of them yet. (anyone own them??)
Phil made one of his Newt suits out of cast aluminum; so hopefully I can pick his brains on this in August.
 Don't you love the flight down here. Hope you sleep well on planes. 
   I caught up with Hugh last week & some of the exostructure was off his Q-sub. When you see it like that you can
appreciate the enormous amount of engineering work gone in to it. I think Hugh is well & truly over it with all the problems
but it's going to be awesome when he get's it diving.
Have a good trip to OZ.
Alan

________________________________
 From: Cliff Redus via Personal_Submersibles <personal_submersibles at psubs.org>
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
Sent: Sunday, July 20, 2014 8:57 AM
Subject: Re: [PSUBS-MAILIST] O2 regulator

Alan

From a Navy document on CO2 they describe the physiological impact of CO2 in the atmosphere:

2-3%  Shortness of breath deep breathing
5%     Breathing becomes heavy, sweating, pulse quickens
7.5%  Headaches, dizziness, restlessness, breathlessness, increased heart rate and blood pressure, visual distortion
10%   Impaired hearing, nausea, vomiting, loss of consciousness
30%   Coma, convulsions, death

A  0-30,000 ppm (3%) or 0-50,000  (5%) sensor is fine but you loss accuracy when the span increases.  These meters are typically +/- 0.5% accuracy based on the span of the meter.  For a 30,000 ppm meter, this gives +/- 150 ppm.  For a 10,000 ppm span, the same 0.5% accuracy meter gives you a +/- 50 ppm accuracy, or three time the resolution of the measurement.  Another reason I like the 10,000 span is for my boat I am trying to stay within the 0-5000 ppm level set by ABS. Normally this sensor is reading 1000-2000 ppm.  The only time is will run higher is when the CO2 absorbent become saturated and is no longer pulling CO2 out of air. So if has been 8 plus hours on one scrubber, I start to get a color change of the absorbent and I see the CO2 ppm level start to continually increase, I know it is time to change the absorbent.  My PLC touch screen has a plotting feature so I have a screen that shows the CO2 and O2 levels plotted over time.  It
 is pretty easy to see with the absorbent become saturated.

So the short answer is I like the better accuracy  I get over the range I would expect to see.

I am sorry to miss the convention as well.  I was looking forward to hearing about the progress you have made on your new one atmosphere boat. Are you still planning on casting the pressure hull?

Next week I will be in your part of the world Australia; not home but close.  No plans to hit New Zealand on this trip.  Though I would like to see how Hugh Fulton is coming along on his QBoat

Cliff

From: Alan via Personal_Submersibles <personal_submersibles at psubs.org>
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
Sent: Saturday, July 19, 2014 3:01 PM
Subject: Re: [PSUBS-MAILIST] O2 regulator

That's a great link Cliff, have bookmarked it.
I am wanting something to link to a plc & they have some treat options.
How come you didn't buy a unit with a wider range?
Phil's life support paper is saying we can take 3% for 1 hour, but the
range on the one you bought is 0 to 1%.
Sorry you aren't making it to Bellingham. It was a real treat seeing the R 300
in Florida.
Alan

Sent from my iPad

On 19/07/2014, at 12:25 pm, Cliff Redus via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

I use a K-30, part number SE-0018 , 0-10,000 ppm (0-1%) CO2 sensor from a company CO2 meters inc. The cost is $85 and it sends a 0-5 VDC output sensor.
>
>
>http://www.co2meter.com/collections/co2-sensors/products/k-30-co2-sensor-module
> Has worked flawlessly.
>
>
>Cliff
>
>
>
>
>
>
>Cliff Redus
>Redus Engineering
>USA mobile:  830-931-1280
>cliffordredus at sbcglobal.com 
>
>
>From: Pete Niedermayr via Personal_Submersibles <personal_submersibles at psubs.org>
>To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
>Sent: Friday, July 18, 2014 7:05 PM
>Subject: Re: [PSUBS-MAILIST] O2 regulator
> 
>
>
>Cliff, What are you using for a CO2 sensor?
>
>Thanks Pete
>
>--------------------------------------------
>On Thu, 7/17/14, Cliff Redus via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>Subject: Re: [PSUBS-MAILIST] O2 regulator
>To: "Personal Submersibles General
 Discussion" <personal_submersibles at psubs.org>
>Date: Thursday, July 17, 2014, 8:30 AM
>
>Hank
>On the R300, I have life support
>module I call the AMOC system (Air monitoring and Oxygen
>Control).  Connected to the box is a 1/4" SS tubing
>with Swagelok fittings connected to a O2 supply from an
>external 2200 psig O2 bottle. I fill this with welding O2
>with a whip.    In the AMOC module is a medical pressure
>reducing regulator (Hudson model 2000).  This regulator 
>reduces the pressure to around 5 psig.  The pressure
>downstream of the regulator is adjustable with a
 maximum
>rate of 15
 SLPM.  The porting on this regulator is two
>1/4" NPT HP ports and one LP port.  Downstream of
>this regulator, I have installed an O2 thermal mass meter/
>controller from Porter. 
>  The model number is 201-FSVP.  This controller can be set
>from 0-10 SLPM via an 0-5V analog input signal. Max
>pressure on the O2 controller is 25 psig.  This O2
>controller also sends out at 0-5V analog output signal of
>the O2 SLPM flow rate.
>Both these items were purchased on
>Ebay at a fraction of list.    I have been very happy
>with the performance of these units.  By measuring the O2
>and CO2 percentages in the cabin, I have a PLC that opens
>and closes this controller to keep the
 cabin O2 % between
>19-22%.  ABS regulations requires that the O2 be held with
>in 18-24%.  The advantage of this system is that it
>automatically accounts for different metabolic consumptions
>rates for O2.  In the AMOC unit, I have a Swagelok needle
>valve in a bypass around this controller so that if both
>main and back up power are lost, the pilot can manually
>adjust the O2 rate
>  into the boat.
>The
>second part to controlling the atmosphere in the cabin is
>scrubbing the CO2.  I initially used a axial flow filter
>with SodaSorb HP.  I found that the axial flow filter did
>not work very well with CO2 in the cabin ranging from 0-7000
>ppm.  Part of the problem was the axial
 filter arrangement
>and part of the problem was the blower was not strong
>enough.  At the 2012 PSUB convention in Vancouver, Alec
>Symth brought the scrubber he was using on Snoopy as a
>show and tell.  His scrubber is an OTS radial filter that
>is used to clean air.  In 2013, I switch to this type of
>scrubber/filer again with SodaSorb HB and the scrubber has
>worked much better.  It consistently keeps the CO2 level
>below 2000 ppm with most of the time it being 1000-1500
>ppm.  ABS rules require that you keep O2 concentration
>below 5000 ppm.  Part of the reason that is works better
>  is the radial design which minimizes the pressure drop
>through the Sodasorb and part is that I have switched to a
>stronger blower.
>Long
>answer to short question.
>
>Cliff
>
>
>
>  
>
>      On Thursday, July 17, 2014 9:27 AM,
>hank pronk via Personal_Submersibles
><personal_submersibles at psubs.org> wrote:
>    
>
>  Hi All,I need to find a pediatric
>flow meter and regulator for Gamma.  Or is there something
>better?Hank
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