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Yes as a home made close circuit rebreather diver i can say that a ppo2 meter is really simple to built.
basicly a simple 10 dollars lcd voltmeter and a pot are enough for the electronics
but with no alarm
a system with an audible alarm can also be built cheaply .
what ojne have to know is that an o2 sensor is a very fragile electrochemical device that can drift from a second to the other with no warning
so any vital ppo2 system need to be doubled or trippled to be abble for the operator to compare the readings
with 2 sensors one can know if the system works (if the reading are close)
with 3 sensors one can know witch sensor is bad in case one starts to drift .
a sensor life is usualy 12 to 24 monthes
as for the humidity problem don't care the r 22's have hydrophobic membranes and works well in hyper humid condensing conditions like rebreathers so i a bigger space like a sub cabin it will definitly be better.
I can help if necessarry.
regards
jean mi
----Message d'origine----
>Date: Sun, 28 Aug 2005 10:13:11 -0400
>De: Al Secor
>A: personal_submersibles@psubs.org
>Sujet: Re: [PSUBS-MAILIST] O2 sensors
>
>Pierre,
>
>O2 sensors measure partial pressure of O2, so if your sub cabin is at 2 atm, the
>sensor will read .42 in air (assuming it's been calibrated to .21 at 1 atm).
>Be aware that condensation on the face of the sensor can lead to
erroneous
>readings so you want to try to avoid condensation directly on the face even
>though some are manufactured with hydrophobic membranes.
>
>A good place to get sensors is from Patrick at oxycheq.com. His prices are very
>reasonable and he provides good service. (I have no relation to Patrick, just
>a satisfied customer). I use Teledyne R-22D sensors in my homebuilt
>rebreather. A very simple O2 meter can be built from a recalibrated DVM
>
module. There are several sources on the web that describe how to do it and I
>think Patrick's webpage also describes it.
>
>Hope this helps.
>
>Al
>
>Al Secor ARS: WA3PWX Scuba Instructor SSI PDIC TDI
>http://www.geocities.com/SubDiverI
>
>
>
>Quoting Marie-Andrée et Pierre :
>
>> Hi guys,
>>
>> After seing Jon's presentation at the convention I decided to go
with a
>> scrubber and a O2 injection device.
>>
>> My question is: Will an oxygen sensor work for a dry-ambient sub? How does
>> the sensor work? I know it give a different voltage outpout depending on the
>>
>> amount of oxygen in the air. but what happened when put under pressure? Will
>>
>> it track PPM of oxygen in the air or the % of oxygen in the air? Will it
>> detect 21% at 1atm, 42% at 2atm, 176% at 5atm,
etc...
>>
>> Does anybody here have experience with a scrubber/O2 system in an ambient
>> sub?
>>
>> The reason I decided to go scrubber/O2 is that I have about 35-40 minutes
>> inside my sub before I feel the effect of too much CO2 in the cabine. If I
>> refresh the air inside the cabine by injecting fresh air from my tanks, it
>> is not very effective and takes alot of air.
>>
>> Thank you all!
>>
>> Pierre "O2" Poulin
>>
>>
>>
>>
>>
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>
>
>
>
>
>
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