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<div dir="ltr" data-setdir="false">Hi Alan,</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">I still think the major advantages of the optical sensor is the digital output and it's expected life of 5 years. But I have a hard time getting past the 25% scale because there's a lot of "head room" between 25-100% and you just don't know where you are in that range. My concern is not from a biological perspective since short term high levels of O2 are not an issue at 1-ATM, but from an environment one...high levels of 02 start representing a real fire danger.</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">Calibration in free air is easiest and why handheld (mobile) sensors are convenient. I'm not sure I would trust just opening the hatch to get fresh air in the vessel, unless you forced fresh air inside with a fan or something. Getting into an open air environment would be best.</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">Jon</div><div dir="ltr" data-setdir="false"><br></div><div><br></div>
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On Monday, August 19, 2019, 05:58:02 AM EDT, Alan via Personal_Submersibles <personal_submersibles@psubs.org> wrote:
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<div><div id="ydp7e23d944yiv9274357921"><div><div></div><div>Jon,</div><div>am having second thoughts about the optical O2 sensor.</div><div>I was given data that said calibration was needed after a while because of a drift</div><div>caused by temperature fluctuations.</div><div>Although calibration would only need to be done every year or two, I would </div><div>need to write a program for that. And I would need to write a program for</div><div>calibration of galvanic O2 sensors if I went with them. So although the optical</div><div>sensors are factory calibrated, this is not going to be that much of an advantage</div><div>to me. They would also be more difficult to source than the standard sensor.</div><div>The optical sensors only have the 0-25% O2 range but I can't imagine going over</div><div>25%. The optical sensor has better accuracy, as all the information I have seen </div><div>on the galvanic sensors say they have an accuracy of +/- 2% on full scale.</div><div>I wonder what procedures Psubbers take with regards to checking calibration</div><div>of their O2 sensors. I am thinking a best practice would be to leave the hatch</div><div>open before a dive & check that the O2 reading corresponds to the standard</div><div>level of O2 in air.</div><div>Cheers Alan</div><div><br clear="none"></div><div><br clear="none"></div><div><br></div></div></div></div>
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