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Thread: Calibrating sensors, how long before diving...

  1. #11
    RBW Member ECho is an unknown quantity at this point ECho's Avatar
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    rEvo Micro FT

    Meg

    Re: Calibrating sensors, how long before diving...

    @Meivi, what unit are you diving?

    I'm on a Meg APECS2.7 and use a head only calibration kit. So, on the evening before diving, I go though the build check list, save for the 5 minute pre-breathe and then shut down the unit, before sealing it up. During that process, per the checklist, I verify the sensor voltages (and PO2 readings) in atmospheric air and then again in a pure O2 environment, using the "head only" calibration kit. If the readings are all correct, there's no need to calibrate. If not, I'll go looking for a reason why, and hopefully address it, before calibrating. BTW, the reason that I don't do the pre-breathe on the night before is that one has to open the unit to turn it on and off, so I shut it off to save the battery after he build. That, then, means that I have to reopen it, turn it on, redo both positive and negative pressure loop checks, and then, finally, do the pre-breathe before the boat leaves on dive day...

    HTH...

  2. #12
    RBW Member Mike_Eitel is an unknown quantity at this point Mike_Eitel's Avatar
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    MeCCRxWi

    MeRAY, MeTravox,MeCCRV"x,Inspi

    Re: Calibrating sensors, how long before diving...

    O2 sensors are little batteries.

    If there is nothing dramatic like a flooding or defect, there is no reason that a sensor changes its 21 ppo2 value fast. So why calibrate too often? You only hide the natural aging.

    On our av1's I like that you can read the mv when startup. Keep an eye on that gives you a nice "feeling" over the health status. Plus the end of dive high O2 probe.

    Only when on startup the calculated ppo value is to different from real one i recalibrate. Don't forget to calculate the hight over see presure when you lookup momentary atmospheric pressure.

    With good sensors i calibrate only in monthly steps.

  3. #13
    Captain Meivi is an unknown quantity at this point Meivi's Avatar
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    Hollis Prism 2

    Re: Calibrating sensors, how long before diving...

    Hmm okey thanks all. But checking readings in air is enough the ...? No need to check linearity between air and pure oxy every time? Course if I still ought to check linearity every time then there is just 2 clicks on the computer to calibrate as well


    Quote Originally Posted by ECho  View Original Post
    @Meivi, what unit are you diving?
    Im diving the Prism2.

  4. #14
    RBW Member ECho is an unknown quantity at this point ECho's Avatar
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    Meg

    Re: Calibrating sensors, how long before diving...

    That's one of the nice things about the Shearwater electronics... Easy calibration. You can also get a head only calibration kit for the Prism 2 from Matt Addison (on here as saveourseas), which greatly reduces O2 required for calibration and/or cell check...

  5. #15
    Captain Meivi is an unknown quantity at this point Meivi's Avatar
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    Hollis Prism 2

    Re: Calibrating sensors, how long before diving...

    Quote Originally Posted by ECho  View Original Post
    That's one of the nice things about the Shearwater electronics... Easy calibration. You can also get a head only calibration kit for the Prism 2 from Matt Addison (on here as saveourseas), which greatly reduces O2 required for calibration and/or cell check...
    Ehm whats that? And here do I find it?

  6. #16
    RBW Member Olsen DK is an unknown quantity at this point Olsen DK's Avatar
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    Prism2

    Dräger Ray

    Re: Calibrating sensors, how long before diving...

    The calibration kit for the Prism2 is this, please see attached.

    It is basically a cover you install on the CCR head instead of the scrubber basket.
    and 2 plugs instead of the in & exhale hoses on the CCR head.

    When you are performing the calibration of the censors you will use less than 5 bar on a 3 ltr bottle.
    Super smart calibration setup. can only recommend it.
    Attached Files

  7. #17
    Captain Meivi is an unknown quantity at this point Meivi's Avatar
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    Hollis Prism 2

    Re: Calibrating sensors, how long before diving...

    Nice, and where do I get one?

  8. #18
    RBW Member jack frisendahl is an unknown quantity at this point jack frisendahl's Avatar
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    no

    Re: Calibrating sensors, how long before diving...

    Quote Originally Posted by Meivi  View Original Post
    Nice, and where do I get one?



    Re: P2 calibration kit
    If anyone is interested in purchasing a P2 Calibration Kit, email me at matthewaddison1@mac.com. The kits are $50.

    Using this kit cuts the O2 usage from 250-300 psi to flood the system to 2 - 3 psi. The rebreather doesn't need to be set up to calibrate. The LP nipple is on the exhale plug so if the solenoid won't fire because of a "CAL FAIL" on all 3 sensors it is easy to flood the head with O2 using the O2 LP hose.


    Jack
    7



  9. #19
    Chett Lehrer Chett.L has much to be proud of Chett.L has much to be proud of Chett.L has much to be proud of Chett.L has much to be proud of Chett.L has much to be proud of Chett.L has much to be proud of Chett.L has much to be proud of Chett.L has much to be proud of Chett.L has much to be proud of Chett.L has much to be proud of Chett.L has much to be proud of Chett.L's Avatar
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    rEvo FT / Hollis P-2/ rEvo lll

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    Re: Calibrating sensors, how long before diving...

    Quote Originally Posted by jack frisendahl  View Original Post
    Re: P2 calibration kit
    If anyone is interested in purchasing a P2 Calibration Kit, email me at matthewaddison1@mac.com. The kits are $50.

    Using this kit cuts the O2 usage from 250-300 psi to flood the system to 2 - 3 psi. The rebreather doesn't need to be set up to calibrate. The LP nipple is on the exhale plug so if the solenoid won't fire because of a "CAL FAIL" on all 3 sensors it is easy to flood the head with O2 using the O2 LP hose.


    Jack
    7


    If you own a Hollis Prism 2, buying the calibration kit for 50 bucks is the best money you ever spent on this unit. It will save you time, money and 02.

    Best regards,
    Chett. L

  10. #20
    Captain Meivi is an unknown quantity at this point Meivi's Avatar
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    Hollis Prism 2

    Re: Calibrating sensors, how long before diving...

    Quote Originally Posted by jack frisendahl  View Original Post
    Re: P2 calibration kit
    If anyone is interested in purchasing a P2 Calibration Kit, email me at matthewaddison1@mac.com. The kits are $50.

    Using this kit cuts the O2 usage from 250-300 psi to flood the system to 2 - 3 psi. The rebreather doesn't need to be set up to calibrate. The LP nipple is on the exhale plug so if the solenoid won't fire because of a "CAL FAIL" on all 3 sensors it is easy to flood the head with O2 using the O2 LP hose.


    Jack
    7



    Sweet, thanks. I'll mail and check if he is still in business ans hope he's able to send to Sweden

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