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Thread: Meg Cell Bypass issue

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    RBW Member Dive!Dive! is on a distinguished road Dive!Dive! is on a distinguished road Dive!Dive!'s Avatar
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    Meg Cell Bypass issue

    Folks
    It seems well accepted that the cell configuration in a Meg offers the potential for bypass of CO2 in the event of a cell failure.
    I dont want to get into a debate about how much of a problem it may or may not be, weather ISC should do a recall etc etc.
    What I'd like to think about is what can we do about it.
    Yes, theres the obvious answers like ' dive another unit' , but although I would like another unit (in additon to the Meg...!) thats not going to happen this year, and its in any case a shame as the Meg has plenty of positive points.
    I have thought of a couple of things:
    1. Redesigned sensor carriage with some sort of enclosure for the sensors. It would be a tight fit and this is beyond (way beyond) what I could do at home. Any of the 3rd party guys thinking about this ?
    2. Doing something about the cells. Looking at them its really only the joint between the body and base plate of the casing thats the issue (I realise its possible the membrane could fail also, but you would have a warning of that on the unit). How about encasaing the cell in shrink wrap to physically reinforce the joint ? I dont know if there's space but it could work ?

    Any other ideas?

    Steve

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    Re: Meg Cell Bypass issue

    Talking completely out of mi arse here but shrinkwrap may solve that problem but the cell wont like being heating. Some people tape the cell...

    A bit of bicycle inner tube, if it fits could make the cell stronger.

    Another approach might be to put something in the back of the cell to hold it in place.
    Try to find a bit of tube, or a bit of hose that fits exactly the extrusion on the butt of the cell, put a small hole in it for the cable and squeeze it between the assembly.

    I think that would be the easiset diy solution....

    PS: Only fiddled with a meg for a very very short time.

  3. #3
    Dave Tomblin wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc's Avatar
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    Re: Meg Cell Bypass issue

    Here is my solution. Since the potential bypass involves the guts of the cell coming loose and bypassing through the large hole where the molex connectors go through, why not replace the cells with R17Ds and then if the guts of the cell come loose there will be no open path for CO2 to travel through. The phono jack connectors could even be installed with a little sealant if you're really paranoid.
    Last edited by wedivebc; 22nd June 2008 at 16:51.
    Cheers,

    Dave....

    www.wedivebc.com

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    RBW Member Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike's Avatar
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    Re: Meg Cell Bypass issue

    Quote Originally Posted by wedivebc  View Original Post
    Here is my solution. Since the potential bypass involves the guts of the cell coming loose and bypassing through the large hole where the molex connectors go through, why not replace the cells with R17Ds and then if the guts of the cell come loose there will be no open path for CO2 to travel through. The phono jack connectors could even be installed with a little sealant if you're really paranoid.
    wont help. look at the pics of failed cell - thats not the way they fail

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    RBW Member mempilot has a reputation beyond repute mempilot has a reputation beyond repute mempilot has a reputation beyond repute mempilot has a reputation beyond repute mempilot has a reputation beyond repute mempilot has a reputation beyond repute mempilot has a reputation beyond repute mempilot has a reputation beyond repute mempilot has a reputation beyond repute mempilot has a reputation beyond repute mempilot has a reputation beyond repute mempilot's Avatar
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    Re: Meg Cell Bypass issue

    Quote Originally Posted by Drmike  View Original Post
    wont help. look at the pics of failed cell - thats not the way they fail
    After searching for this, the only threads I can find have to do with cell functionality failure and not physical failure.

    Can you please link to the post with these pictures? I would like to see them.

    Thanks!

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    Re: Meg Cell Bypass issue

    Quote Originally Posted by Dive!Dive!  View Original Post
    Folks
    It seems well accepted that the cell configuration in a Meg offers the potential for bypass of CO2 in the event of a cell failure.
    I dont want to get into a debate about how much of a problem it may or may not be, weather ISC should do a recall etc etc.
    That is precisely the wrong attitude that is serving rebreather manufacturer's interests and not users.


    Quote Originally Posted by Dive!Dive!  View Original Post
    What I'd like to think about is what can we do about it.
    Yes, theres the obvious answers like ' dive another unit' , but although I would like another unit (in additon to the Meg...!) thats not going to happen this year, and its in any case a shame as the Meg has plenty of positive points.
    Those positive points in my view are irrelevant if a user still has the fault that is capable of rendering a user impaired by severe CO2 without warning and no mitigation path by inspection/maintenance.

    It is not within most users' remit nor professional scope to suggest alternative design ideas for potentially life-threatening failure modes. Furthermore, in doing so, you are completely undermining any effort to make ISC accountable for immediately taking the appropriate actions in relation to the number of current units still affected by this problem.

    Quote Originally Posted by Dive!Dive!  View Original Post
    I have thought of a couple of things:
    1. Redesigned sensor carriage with some sort of enclosure for the sensors. It would be a tight fit and this is beyond (way beyond) what I could do at home. Any of the 3rd party guys thinking about this ?
    2. Doing something about the cells. Looking at them its really only the joint between the body and base plate of the casing thats the issue (I realise its possible the membrane could fail also, but you would have a warning of that on the unit). How about encasaing the cell in shrink wrap to physically reinforce the joint ? I dont know if there's space but it could work ?
    NO. How about the manufacturer of the unit, which, let's not forget, is held out as life-support equipment by the general use of a solenoid and electronics, facilitates a safety notice/recall to all affected users. The onus is unquestionably upon the manufacturer to decide how to proceed, NOT the users.

    Your solutions won't work in any case (don't mitigate the failure path) and do not provide scope for proper integration of sensor architecture alteration with the rest of the unit's functionality.

    Regards

    AnneMarie

  7. #7
    Dave Tomblin wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc's Avatar
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    Re: Meg Cell Bypass issue

    Quote Originally Posted by Drmike  View Original Post
    wont help. look at the pics of failed cell - thats not the way they fail
    Yeah but I thought that was an anomoly due to bad batch of cells. Joe Radomski mentioned a failure mode that involved the circuit board coming loose inside. This would at least reduce that risk. I do realize it was R17Ds which you had fail as well.
    Cheers,

    Dave....

    www.wedivebc.com

  8. #8
    Dave Tomblin wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc's Avatar
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    Re: Meg Cell Bypass issue

    Quote Originally Posted by mempilot  View Original Post
    After searching for this, the only threads I can find have to do with cell functionality failure and not physical failure.

    Can you please link to the post with these pictures? I would like to see them.

    Thanks!
    http://www.rebreatherworld.com/showthread.php?t=11518
    Cheers,

    Dave....

    www.wedivebc.com

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    Re: Meg Cell Bypass issue

    Quote Originally Posted by am  View Original Post
    That is precisely the wrong attitude that is serving rebreather manufacturer's interests and not users.


    NO. How about the manufacturer of the unit, which, let's not forget, is held out as life-support equipment by the general use of a solenoid and electronics, facilitates a safety notice/recall to all affected users. The onus is unquestionably upon the manufacturer to decide how to proceed, NOT the users.

    Your solutions won't work in any case (don't mitigate the failure path) and do not provide scope for proper integration of sensor architecture alteration with the rest of the unit's functionality.
    Whilst I agree that the manufacturer is responsible to provide a fix, if you have invested many thousadns of dollars on a unit and find an issue that the manufacturer is not doing any thing about then self help might be the only solution.

    Since it seems the users voice is not working to get changes made it either sell the unit (and pass on a known fault to an other user) and buy one with out a fault or fix it yourself. I for one would prefare to fix it and then ensure I advise others not the buy that unit.

    Mark

  10. #10
    RBW Member Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike's Avatar
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