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Thread: Adapter to use medical tank as a scuba tank

  1. #11
    RBW Member ocean20178 is an unknown quantity at this point ocean20178's Avatar
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    Re: Adapter to use medical tank as a scuba tank

    Quote Originally Posted by whynot?  View Original Post
    There are many manufacturers that make this adapter (for transfilling etc) but be careful doing this. The pin valves aren't certified for UW use and as such may be more susceptible to corrosion. If you do decide to go this route be sure and flush the valve with fresh water thoroughly after diving.

    The other thing you will want to get is a knob for easy on/off of the valve should you need to do this UW. Or convert the cylinder to a CGA450...
    Great, thanks for the advice! I found a cga 870 adapter and a bodock seal at northeastscubasupply.com/medical-oxygen-fittings/ . It is designed for transfilling . Should I be concerned about water possibly getting into the tank?

  2. #12
    RBW Member whynot? will become famous soon enough whynot? will become famous soon enough whynot? will become famous soon enough whynot? will become famous soon enough whynot?'s Avatar
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    MK15.5, MK25

    Re: Adapter to use medical tank as a scuba tank

    Quote Originally Posted by ocean20178  View Original Post
    Great, thanks for the advice! I found a cga 870 adapter and a bodock seal at northeastscubasupply.com/medical-oxygen-fittings/ . It is designed for transfilling . Should I be concerned about water possibly getting into the tank?
    As long as you KEEP the tank pressurized... NO. This is the reason we were all taught to keep 500 psi in a tank after a dive

    If you drain a tank on a dive, you have a bigger issue than water ingress to worry about.

    The problem is salt getting into places that you can't thoroughly clean with a freshwater rinse and as Ken points out, the weak-factor of the sealing surface - a simple EXTERNAL washer. Hint, avoid using a pin-index setup UW.

  3. #13
    RBW Member ocean20178 is an unknown quantity at this point ocean20178's Avatar
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    Re: Adapter to use medical tank as a scuba tank

    Quote Originally Posted by whynot?  View Original Post
    As long as you KEEP the tank pressurized... NO. This is the reason we were all taught to keep 500 psi in a tank after a dive

    If you drain a tank on a dive, you have a bigger issue than water ingress to worry about.

    The problem is salt getting into places that you can't thoroughly clean with a freshwater rinse and as Ken points out, the weak-factor of the sealing surface - a simple EXTERNAL washer. Hint, avoid using a pin-index setup UW.
    You've made some great points. I'm reconsidering diving with a pin-index setup. Do you think the bodock seal sold at northeastscubasupply.com would provide a better seal?

  4. #14
    RBW Member whynot? will become famous soon enough whynot? will become famous soon enough whynot? will become famous soon enough whynot? will become famous soon enough whynot?'s Avatar
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    Re: Adapter to use medical tank as a scuba tank

    Quote Originally Posted by ocean20178  View Original Post
    You've made some great points. I'm reconsidering diving with a pin-index setup. Do you think the bodock seal sold at northeastscubasupply.com would provide a better seal?
    I'd say no.

    It's basically a flat rubber washer enclosed in a brass (or SS) ring. While this may seem better, it isn't. What you want is a "captured" o-ring. A "K valve" would be the minimum, a DIN fitting is much safer. The reason for this is if the yoke fitting from the regulator (1st stage) gets bumped and jarred, the o-ring can extrude (pinch and blow out) and then you are SOL.

    This is a real world situation issue; not one I would want to happen to me UW. The CGA 540 valve is a metal to metal coupling. Metal to metal is common is some military versions of dive gear, Swagelok fittings are an example on the MK 15, 16 and 25 (all of which I dive).

    Still, I would highly advise using common valves with o-rings, use the right tool for the right application.

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