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VR3 ppO2 Corrosion Question

Discussion in 'Rebreather Diving' started by hornetplt, Oct 31, 2004.

  1. hornetplt

    hornetplt Angel Fish

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    I have the VR3 ppO2 sensor attached via a P-port into my Azimuth and have been dealing with corrosion on one(and only one) of the female ends of marine connector(connects end of sensor cable to I/O port on computer)only after a few dives. There does not appear to be any water entering the o-ring sealed connector but find that the corrosion still accumulates. Associated with the corrosion(oxidation) are erroneous ppO2 readings......the only cause that I can think of is the fact that I leave the marine connector attched to the computer both in and out of the water. The connector has 2 plastic plugs that will seal each end of the connector if disconnected, maybe this is something I should be doing after diving. But isn't it a sealed system. Any help would be most appreciated! Thanks!
     
  2. padiscubapro

    padiscubapro Cave Instructor

    # of Dives: I'm a Fish!
    Location: New York
    2,084
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    Every VR3 I have ever seen has a femal connector on the computer and a MALE end on the cable

    If you are getting greenish discoloration you definately have water entry.. Fisher connectors have the O-ring in the connector on the computer, this is NOT a face seal!carefully examine the O-ring anythingon it willallow water seepage.

    If this is the old 2 pin connector its pretty immune to how the cable is plugged in but if its the larger connector you must make sure the connector is pushed fully forward and stays that way.. the connector normally has movement when "locked" but a seal is only guaranteed if it is pushed fully forward and stays that way, onceit is underpressure it resists backing out well..

    I suggest you put some silicon lube on the metal ring on the connector on the cablethis machined ring is what the oring in side mates to. If you have ANY imperfections on this outer ring, you will never get a seal.
     
  3. hornetplt

    hornetplt Angel Fish

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    Thanks for the response Padiscubapro. Yes, the I/O port attached to the computer is female end and I have been placing silicone on male end as described in last post. During the last portion of I/O port connection, resistance will be felt and a final "click" once the connection is complete. Because water actually enters the port up to the inward seal, upon port seperation, there will always be a few water droplets on the outside of the male connector and on the outer walls of the female side. I have never found any water on the center female port, which leads me to believe there is no water actually entering the port connection. The connector itself is the larger Fisher type. Why would there be a oxidation on only one of the copper female ends?

     
  4. padiscubapro

    padiscubapro Cave Instructor

    # of Dives: I'm a Fish!
    Location: New York
    2,084
    14
    0
    Is this the computer side??

    If so you have to look at the pin.. The pins that have the highest voltageand current flow will get this way..

    For example, The Hammerhead CCR controller uses a similiar connector, if ANY water gets into the connector 2 pins get corroded its always the same two pins.. it happens to be the pins for the solenoid.

    I dont know the cable for the sensor but I was under the impression that only the necesary pins on the cable are now wired, while every pin on the computer connector is wired (for future uses). This way only pins in contact with the computer would discolor.. If you meaure the two pins with corrosion I am willing to bet one is some type of voltage source and one is a ground.

    The pins are supposed to be gold plated, if the copper is showing, you will get all types of oxidation even if water doesnt maintain contact with it, bare copper oxidizes quite easily. Once you have a high current sraw across the pins due to water the gold plating (which is very thin) gets "burned" off..
     
  5. hornetplt

    hornetplt Angel Fish

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    Padiscubapro,
    Thank you for your prompt, informative responses. The female end is on the computer itself and I will continue to monitor the oxidation and clean as necessary. It is not a problem with all the pins(only one) and just as you have explained it is the one for ppO2 sensor. Thanks again!

    If so you have to look at the pin.. The pins that have the highest voltageand current flow will get this way..

    For example, The Hammerhead CCR controller uses a similiar connector, if ANY water gets into the connector 2 pins get corroded its always the same two pins.. it happens to be the pins for the solenoid.

    I dont know the cable for the sensor but I was under the impression that only the necesary pins on the cable are now wired, while every pin on the computer connector is wired (for future uses). This way only pins in contact with the computer would discolor.. If you meaure the two pins with corrosion I am willing to bet one is some type of voltage source and one is a ground.

    The pins are supposed to be gold plated, if the copper is showing, you will get all types of oxidation even if water doesnt maintain contact with it, bare copper oxidizes quite easily. Once you have a high current sraw across the pins due to water the gold plating (which is very thin) gets "burned" off..[/QUOTE]
     

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