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Burst discs: Yes they burst when they shouldn't

Discussion in 'Tanks, Valves and Bands' started by 2airishuman, Jun 6, 2017.

  1. KWS

    KWS ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: SE TEXAS
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    On that i agree with you. that is why i have not seen a 200 bar fill connector. the instructor said they are hard to find and often was used in systems that had different regulated outputs. The prutruded pin items protects the tank and the thread system protects teh regulators when they made 200 bar regs.
     
  2. JamesBon92007

    JamesBon92007 Loggerhead Turtle

    # of Dives: 2,500 - 4,999
    Location: Southern California...too far from the ocean
    2,881
    1,111
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    Several times I came across "$6" as the going rate for a burst disc however I am finding them at around twice that. The best price I've found is about $11. Should I keep looking or is that likely to be the lowest price I will find?
     
  3. tbone1004

    tbone1004 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: I'm a Fish!
    Location: Greenville, South Carolina, United States
    15,248
    6,568
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    I linked to Northeast Scuba Supply where the prices are about $3.50 for the actual disc and $0.50 for the washer if you stay with 3 piece assembly. If you switch to 1-piece, they're $8 for non-sherwoods, and $11 for Sherwood 5000 valves and manifolds.
     
  4. JamesBon92007

    JamesBon92007 Loggerhead Turtle

    # of Dives: 2,500 - 4,999
    Location: Southern California...too far from the ocean
    2,881
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    Thanks! That reminds me of how much they used to cost.

    Are the Sherwoods a different thread? Some of my valves are Sherwoods, some are not.
     
  5. tbone1004

    tbone1004 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: I'm a Fish!
    Location: Greenville, South Carolina, United States
    15,248
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    some are, John wouldn't differentiate if there wasn't a difference. I haven't pulled burst disc assemblies on the Sherwood 5000's in a long time. I'm about to, but haven't in quite a while
     
  6. JamesBon92007

    JamesBon92007 Loggerhead Turtle

    # of Dives: 2,500 - 4,999
    Location: Southern California...too far from the ocean
    2,881
    1,111
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    I just went and looked and I have at least one Sherwood 5000 on an AL80. It attaches at the end opposite of the valve knob. Most of my other burst discs (on the steel 72s) are opposite of the valve opening/regulator connection. One of the valves on an old 72 is opposite the knob which makes me suspect that the previous owner switched valves and it may have a higher pressure burst disc. It is also a Sherwood valve and has a sticker that says 3000 psi service pressure so I guess that confirms it.

    I'm going back and forth as I'm writing this so this is a "discovery" post. :wink:
     
  7. BRT

    BRT Orca

    9,549
    5,714
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    I just had 7 hydro'd and didn't even send the valves along.
     
  8. tbone1004

    tbone1004 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: I'm a Fish!
    Location: Greenville, South Carolina, United States
    15,248
    6,568
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    location shouldn't matter on where it is. The Sherwood 5000 is a series of valves but there were several in the series
     
    JamesBon92007 likes this.
  9. Jay

    Jay Need to dive more!

    # of Dives: 50 - 99
    Location: Melbourne, OZ.
    610
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    I've come across several postings about burst discs bursting on land, but not yet to find any incidents whilst diving. Are there any stats on this, even anecdotal? And how seriously injured was the diver?

    If a burst happens underwater wouldn't the tank take some time to fully flood? (Reason for Q: OOA and kicking up 11+kg for an AL80 to your buddy would be hard, but if you're aware that 11kg of negative was happening over the next x minute(s) ...)

    Am I correct in assuming the ubiquitous AL80 tanks that are used around Asia have burst discs?

    If a disc bursts whilst diving, assuming the diver's still conscious/reasonably uninjured, is there likely to be 'shrapnel' from it? Just thinking through a what-if the wing's also punctured.
     
  10. TrimixToo

    TrimixToo Regular of the Pub

    # of Dives: 200 - 499
    Location: New York State
    890
    901
    93
    I likewise replace mine at hydro time. The valve is taken apart, O2 cleaned, the seat inspected or replaced, and the burst disc replaced. I have had one failure, ever, and it was a tank sitting in the car on a hot day before a planned dive trip. (As pointed out upthread, it doesn't get hot enough to reach the burst pressure, but I guess that one was just a bit weaker than usual.)
     

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