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Re: [PSUBS-MAILIST] O2 & CO2 sensors
Gary, for non ABS boats, I think this would work. For ABS, rules require
monitoring CO2 ppm in order to stay below 5000 ppm. Since I am trying to
stay within ABS framework, I will need sensor. Like everyone else that is
scrubbing CO2, I plan on using a clear cartridge holder and absorbent that
changes color on saturation as a backup indicator. I cur with thoughts on
safety issues related to high O2 level and high cabin pressure.
Cliff
----- Original Message -----
From: "Gary R. Boucher" <protek@shreve.net>
To: <personal_submersibles@psubs.org>
Sent: Thursday, September 12, 2002 11:17 AM
Subject: Re: [PSUBS-MAILIST] O2 & CO2 sensors
> Hey Cliff,
>
> Just had a primitive thought... Do you really "need" a CO2
> sensor? Many of the CO2 scrubbing products available use colored
> indicators which will allow you to see if the material has been
> exhausted. Wouldn't a positive air flow indicator on the scrubber work as
> well? If you know that cabin air is flowing through the material and the
> material is still active, couldn't you assume that the CO2 is being dealt
> with?
> I do not use a scrubber on my sub, just SAR, surface and
> replenish. However, my biggest fear would be from excess O2 or from
> overpressurization of the cabin. Excess O2 levels can be a fire hazard
> (remember NASA's problem). And, if for some reason, the inside of the sub
> had to be pressurized with a high O2 concentration, it could be toxic to
> the occupant. The O2 sensor could warn you of this danger and a
barometer
> could warn against excess cabin pressure. The flow meter and visual
> inspection of the scrubber material could warn against a potential lack of
> C02 removal.
> I may just get me an O2 sensor for $77. Course, I have no O2 to
> sense. I love working with almost any type of sensor. Makes me want to
> run design a circuit. :-)
>
> Gary
>
>
>
>
> At 06:32 AM 9/12/2002, you wrote:
> >Alec, I to am working the O2 & CO2 sensor issue. The www.amronintl.com
site
> >has a number of analyzers for O2, CO2 and combined units. This is a great
> >site. You have to set up an account with them to get prices. Having set
up
> >an account and checked out their prices, they are definitely set up for
> >commercial traffic. Example, rack mounted O2 &CO2 unit (Sub Mk II - CO2,
> >O2, Depth) is over $7,000!
> >
> >Best I have found so far for Oxygen sensor is to use the Maxtec, formally
> >Ceramatec, CAG-250 sensor.
> >http://www.cisatlantic.com/trimix/Analyzer/analyzer.htm shows how you
can
> >build a simple unit out of a CAG-250 sensor ($77) and some simple
electrical
> >components. Since I am using a PLC and a touchscreen display, all I will
> >have to do convert the mV signal from the CAG-250, that is proportional
to
> >O2 partial pressure, into a 4-20 mA signal and waire to my PLC analog
input
> >module.
> >
> >So far I have not found a economical CO2 sensor. If anyone has a lead on
a
> >economical 4-20mA or mV output sensor for CO2, please post.
> >
> >Cliff
> >
> >
> >----- Original Message -----
> >From: "Alec Smyth" <Asmyth@changepoint.com>
> >To: <personal_submersibles@psubs.org>
> >Sent: Tuesday, September 10, 2002 2:09 PM
> >Subject: RE: [PSUBS-MAILIST] sofnolime
> >
> >
> > > Adam,
> > >
> > > I'm just building my scrubber. What are you using to monitor the O2
and
> >CO2? I'm curious if you've come across any economical analyzers you'd
> >recommend. Or are you bilding your own?
> > >
> > > thanks,
> > >
> > > Alec
>
>