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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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    My under standing is the burst discs are a USA thing for fire fighting purposes. the disk will blow before that tank explodes in a burning building the rupture factor in the US if i remember is a 4x factor. rupture psi divided by 4 is working pressure burst blow is shy of 2x working pressure.
     
  2. KWS

    KWS ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: SE TEXAS
    4,114
    904
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    they are a USA thing to protect fire fighters in theatthe plug will blow before the tank ruptures and flying metel injurs te fire fighters. look at teh valve picure in another post and it is item 11. the disc is a little wafer about 3/8 in diameter it goes in a hole in hte valve and a bolt is screwed in hte threaded hole to hole it in. the bolt has a hole up the middle of it and out the side of the HEX sides (2). when the disc blows the air exits up the hole in the bolt and out the sides of htehex surface.

    harrison-burst-disc__88469.1367870518.500.750.jpg


    the disc is the silver part surrounded by the copper. you can see the holes in the sides of the hex, It looks lke the disc on this one is recessed into the plug and may not be replacable.



    On this valve it is item 4122-4135e (tothe right ) the large piece is the plug and the small parts to teh left are the disc. In this one the disc is replaceable with out the plug. And yes it is often opposite the the valve operator. the disc is basically a thin piece of metal like a mini coin that has a thickness that will rupture at a set pressure that is well below the rupture pressure of the tank walls. the parts list for this one calls it a safety assembly and is 5.35 in cost.

    thermo_valve_scematic_parts.jpg
     
  3. tbone1004

    tbone1004 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: I'm a Fish!
    Location: Greenville, South Carolina, United States
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    In Europe the 300bar whips will not seat against 200bar valves. Look at the link in post #24 to see what it looks like.
     
  4. Storker

    Storker Divemaster

    # of Dives: 100 - 199
    Location: close to a Hell which occasionally freezes over
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    No, I don't. Things may be different on your side of the pond, but over here a 300 bar whip won't seal on a 200/232 bar tank valve. I've filled enough tanks to be pretty darned certain about that.
     
    Diving Dubai likes this.
  5. KWS

    KWS ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: SE TEXAS
    4,114
    904
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    There is a lot more to it than that. In a dive shop you are engaging in commerce. Whether DOT covers it or OHSA says you will not have hazzardous material unless it is treated like it will be transported. The insurance has a bunch of say what you can do also. IE your tanks have to be standing up and secured per osha. Just like if you were transporting them. Burst discs are a fire issue so they are probably covered under the fire marshall cloke. just like too many people in your store at one time. I would not push those limits in a public forum. like a business.
     
  6. KWS

    KWS ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: SE TEXAS
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    Older din regs did not have the 300 bar 7 thread fitting. Now as far as Inow all regs are made to work on 300 bar. But some older ones are still out there. To be honest i have not seen a 200 bar fill whip. Only 300 bar whips. I have seen 200 bar din regs and they will not seal on a 300 bar valve.
     
  7. KWS

    KWS ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: SE TEXAS
    4,114
    904
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    our 300 and 200 are the same except for the number of threads.
     
  8. Storker

    Storker Divemaster

    # of Dives: 100 - 199
    Location: close to a Hell which occasionally freezes over
    11,846
    8,241
    113
    I took my OW in '12, and by that time every DIN reg was 300 bar. So I've never seen a 200/232 bar DIN reg, but I've filled quite a few 200, 232 and 300 bar tanks the last five years.
     
  9. Storker

    Storker Divemaster

    # of Dives: 100 - 199
    Location: close to a Hell which occasionally freezes over
    11,846
    8,241
    113
    They're not here on the right side of the pond.
     
  10. KWS

    KWS ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: SE TEXAS
    4,114
    904
    113
    You are correct about that fitting it prevents a 300 bar high source from being connecting to a 200 bar tank. I have seen those.

    Here is what i have on my fill station it will mate to both 200 and 300 bar valves.

    45017.jpg


    Our 200 bar valves are many times refered to as combo valves as they have an insert to allow use with a yoke reg and a 300 bar valve does allow the insert to function. You can count the threads. these do work on on 300 and 200 and are the common fill whip item. I will say I have only seen one time a tank that was a 300 bar tank. but i have seen many 300 bar valves. they have a pit n the bottom of them that the 200's do not have for that probe to extend in on the other valve you referenced. Our 300 bar regs look like this also.
     

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