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cootwo O2 sensor replacement and CO calibration

Discussion in 'DiveNav' started by mikeny9, Oct 26, 2017.

  1. mikeny9

    mikeny9 Contributor

    # of Dives: 200 - 499
    Location: New York, New York, United States
    154
    41
    Hello,

    My cootwo is telling me I need to replace the sensor and perform a CO calibration. I sent an email regarding this to customer.service@divenav.com 3 days ago but haven't received a response.

    Can I perform the CO calibration myself somehow? Where do I get replacement sensors? Are there directions on how to take the unit apart to replace the sensor?

    Thanks.
     
  2. tbone1004

    tbone1004 Technical Instructor ScubaBoard Supporter

    # of Dives: I'm a Fish!
    Location: Greenville, South Carolina, United States
    18,780
    11,303
    fun fact.
    So I didn't want to send it back for the firmware update or calibration because it was very expensive and I've been largely unsatisfied with their level of customer service. Still can't believe they didn't design the thing to firmware flash via USB or through the app.
    Doubt you'll see a response here, but I may be surprised.

    If you want a down and dirty way, you can breathe into it and just tell it that it is a higher level of CO than you are putting into it. If you're a non-smoker you should be exhaling around 5ppm.
    If you're a smoker, it will be somewhat higher than that, and conveniently somewhere around the 20ppm calibration gas.
    Obviously that means you have a bogus calibration but since most of us use it as a "it's there, or it isn't", then whether it is 4ppm or 6ppm doesn't really matter.

    Now. If you have a good relationship with your local fire department and they have a newer Bauer compressor *others may have it*. There should be both 0ppm and 20ppm calibration gas bottles, as well as a flow regulator inside of the compressor housing. Mine has the mini Unicus. In the picture below, you can see the door in the middle of the compressor. The two calibration bottles are on the wall between the compressor head and the fill station. They're white, you can't miss them.
    The flow limiter and adapter to get onto those bottles is the same fitting as the mini coleman propane bottles so technically you could redneck engineer it with one of those and some air hose. The compressor should have that fitting inside it though, but it is hiding. In the unit we have, it is clipped in down by the CO monitor for this compressor. That is on the side door, by the bottom hinge, and about 6" in from the door. Kind of have to get on the floor and look in there to find it *don't do it with the compressor on*. Now you have free cal gas and flow limiter. That's how I do mine

    BAU-UnicusIIICompressor-5.jpg
     
    MikkelBC likes this.
  3. DiveNav

    DiveNav ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: Southern California
    3,889
    489
    Hi,
    please PM me with your email address and I will check if your email ended up in our spam folder.
    The CO sensor should be replaced every 2 years and calibrated every year.
    Yes, you can calibrate the CO sensor yourself. See our support forum HERE
    You can purchase a CO sensor from our online store HERE.

    If you send in your cootwo for CO calibration we will perform the firmware upgrade for free.
     
  4. mikeny9

    mikeny9 Contributor

    # of Dives: 200 - 499
    Location: New York, New York, United States
    154
    41
    I don't think the "breathing into it" method for calibration will work because the CO part of the screen is telling me it needs calibration and won't report any number. My local FD is FDNY, and all of their fills occur on Riker's Island, which is home to a large jail facility. Unless I plan on being jailed and convincing the guards to let me calibrate my analyzer I don't think it's a viable solution.

    I just sent a PM, thanks. Also, the first link you provided is also a link to the store, not a forum.

    How much would it be for CO calibration and and O2 sensor replacement if I send it in?

    Thanks,
    Mike
     
  5. tbone1004

    tbone1004 Technical Instructor ScubaBoard Supporter

    # of Dives: I'm a Fish!
    Location: Greenville, South Carolina, United States
    18,780
    11,303
    You have to open up the app on your phone and go find the calibration menu for CO and then you can breathe into it while you are watching it on the phone screen. Again, not an accurate calibration, but if you can find a smoker, it should be around 20ppm and you're getting a go-nogo on it in the interim
     
    mikeny9 likes this.
  6. WarrenZ

    WarrenZ The Ultimate Bad Example ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: Las Cruces NM
    4,134
    4,285
    Calibration gas is available from Grainger if you want to go that way.
     
  7. guruboy

    guruboy Divemaster ScubaBoard Supporter

    5,116
    814
    I wonder how CO sensors degrade. Are they similar to O2 sensors?
     
  8. guruboy

    guruboy Divemaster ScubaBoard Supporter

    5,116
    814
    mikeny9 likes this.
  9. mikeny9

    mikeny9 Contributor

    # of Dives: 200 - 499
    Location: New York, New York, United States
    154
    41
    Calibration gas requires some sort of low-flow regulator doesn't it?
     
  10. tbone1004

    tbone1004 Technical Instructor ScubaBoard Supporter

    # of Dives: I'm a Fish!
    Location: Greenville, South Carolina, United States
    18,780
    11,303
    mikeny9 and northernone like this.

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