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Close Call at the LDS and a High Pressure Reminder...

Discussion in 'Basic Scuba Discussions' started by CuzzA, Jul 16, 2016.

  1. CuzzA

    CuzzA Solo Diver

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    So, I'll start by saying I'm going to pick some lotto numbers for tonight's drawing.

    In preparing for what has now become weekly diving :) I usually just stop by my LDS on Saturday's to fill tanks for Sunday dives, sometimes Monday. Today was no different than any other day, but I had my 3 year old with me. He's came with me before, but never to fill tanks as I usually just run out solo get what I need and come home to pack up.

    Nothing out of the ordinary when I arrive. Chat with the employee in today about our lives, my wife is occupying my son as he touches every piece of dive gear in the shop and then we start filling my tanks. Of course this immediately peaked my son's curiosity and he wanted to get close just like any kid would. All of the sudden after about 30 seconds I got a gut feeling that he should not be anywhere near tanks when they're being filled. Against his will, I force him to get away from the tanks and sent him to the middle of the small strip plaza shop with his mother. During all of this I'm chatting with the employee about how often burst discs let loose as I was explaining why I didn't want him near the tanks and no sooner than he finished saying, "Ah, it's pretty rare. I've had four let go in five years of working here." BOOM!!! PHSSSSS!!! I run grab my wife and son and head toward the front door and then stop before exiting, now realizing if the tank exploded I'd probably be dead and I wouldn't hear gas escaping. Simultaneously the employee ran through a door toward the back of the shop. Neighbors in the strip plaza come over to make sure everything is alright. Of course my son is scared and says, "Let's get out of here!" But just like any three year old he was over it a minute later and continued on touching dive gear.

    The tank amazingly left the ground by about a foot, blew out the ceiling tile and unfortunately landed right on my new Vindicator knob subsequently bending the valve stem and cracking the knob. What was going to be 10 bucks in topping off tanks with air turned into $25 in repairs plus another $14 for a full EAN fill on that tank. I'll come back to that in a moment.

    So, how incredibly lucky that for some reason I had the intuition to get my son away from the tanks. He was literally right by them and had that happened when he was next to them who knows what kind of injury he could have sustained. High pressure gas to his eyes and face would have been horrific. I can't explain why that feeling came over me, perhaps that's just being a dad. We see danger. From now on I don't think I'm going to bring him to the shop when I fill tanks and I hope this story gives a little reminder about how powerful gas is at 3,000+ psi.

    Now, back to the cost/repair issue. I left feeling a little disappointed. Not at all about the money for the new knob and valve stem, although I do wonder if I should have been responsible for that. Of course I expect to pay for the new burst disc, but this is where I question whether tanks should be secured in some way when filling. I know it's rare for a burst disc to let go, but I wonder if it would be prudent for shops to at least secure tanks when filling since that is when there is the highest probability of a failure. Securing a tank in some fashion would have saved my tank from the damage and added cost to repair.

    Nevertheless, all is well and I'll be underwater tomorrow. :wink:

    Stay safe!
     
    Last edited: Jul 16, 2016
    mdb likes this.
  2. davetowz

    davetowz Dive Shop

    # of Dives: 2,500 - 4,999
    Location: usa, Ohio
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    Why did the Burst disc let go? Was the tank overfilled? Burst disc loose? Installed too tight?
     
  3. Pao

    Pao Manta Ray

    # of Dives: 200 - 499
    Location: Manila, Philippines
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    Is it that dramatic when the burst disc goes? Is it really the burst disc or the entire plug that went? I thought it was designed to vent gas at holes at the sides of the plug?
     
  4. drrich2

    drrich2 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: Southwestern Kentucky
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    Thanks be to God your son was removed before this happened. I, too, would like to know if that was 'typical' of a burst disc event. I've never seen one.

    Richard.
     
  5. John C. Ratliff

    John C. Ratliff Instructor, Scuba

    # of Dives: I'm a Fish!
    Location: Beaverton, Oregon
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    James,

    This is what we in the safety profession call a "near miss." It should be investigated by the owner as if your child was injured. By the way, he could easily have had hearing damage if he had remained close to the cylinder when the Overpressure disc released. Have the dive shop owner view the following PowerPoint presentation by Bill High of PSI/PCI and NOAA:

    http://faculty.wwu.edu/schwarn/Trai...ointFormats/HandlingHighPressureCylinders.ppt

    Note that your child should not have been able to simply walk to the filling station. There should be a door and physical barrier to prevent that and allow only authorized personnel into the area.

    Also, look at your burst disc assembly. There should be at least two holes for the air to escape; these cancell the force of the escaping air. Mine now have three, at 1/3 circumference each, to cancel out those forces so that the tank doesn't move much when the disc bursts. These are replaced at hydro time as a best practice; some dive shops change them out at visual inspection time (yearly), but that may be overkill.

    'Hope this helps.

    SeaRat
     
    cerich and wetb4igetinthewater like this.
  6. Pao

    Pao Manta Ray

    # of Dives: 200 - 499
    Location: Manila, Philippines
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    My thoughts exactly.
     
  7. BurhanMuntasser

    BurhanMuntasser Dive Charter

    # of Dives: I'm a Fish!
    Location: Nomad
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    The fill station shouldn't be anywhere near customers at all. My fill station was at the back of the store and no customer was allowed there. A fill station isn't a playground for children either.

    Burst discs bursting spontaneously without clear reason is rare indeed. The disc gets weaker as it gets older and it may burst at lower pressure than its rated burst pressure especially if the owner of the tank overfills the tank and/or is careless about the proper care of the valve including rinsing with fresh water.
     
    Last edited: Jul 17, 2016
  8. KevinNM

    KevinNM DIR Practitioner

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    At my LDS the fill station is in an employee only area, but I've been a customer for longer than all of the employees have worked their so I get told to drag my stuff back there to get it set up. I let them actually turn any valves and push any buttons.

    In Florida the 3 shops I've looked at in any detail all are set up so the customer can get their tanks filled in their vehicles, and it's often 2 sets of 130 doubles that they are filling.
     
  9. gcarter

    gcarter Orca

    # of Dives: 200 - 499
    Location: Ottawa, Canada
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    First off, glad everyone is all right and no injuries :)

    Next a question: why do you wonder if you should be responsible for the valve damage when it was your burst disc that failed? How is that the shops fault? Just curious.
     
  10. CuzzA

    CuzzA Solo Diver

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    I'll have to be brief without a whole lot of thought with this reply as I'm getting ready to depart on my way to the marina. First thanks for the concern of my son. I would have been devastated if something happened to him. Thank God is right, @drrich2.

    @davetowz The tanks were used when I bought them (recent hydro) and although I had them VIPed and O2 cleaned, I did not have the burst discs replaced. For all I know they could be the original discs. The disc was rated at 4000 PSI and according to the shop, on that particular fill whip the max they can achieve is 3800. I don't know much about high pressure compressors, but I recall something about their compressor being capable to hit 10,000 psi. I assume you can manually set the maximum operating pressure? I don't know what the pressure was when it let go, but I'm sure it was pretty high as it already had around 1200 psi to start. My other matching tank was being filled at the same time without issue.

    I will post a picture of the disc, but the air escape holes (maybe 3) did not appear to be occluded. I always dunk and hose off my tanks after diving. Of course after the fact I have no idea if there could have been debris in the holes which altered how it was designed to fail. I do not know why the tank reacted so violently. Perhaps someone with more experience in disc failures can chime in. But I guess we could relate it to a pressure washer hose. Pull the trigger and the gun wants to move out of your hand. Hell, just a garden hose with a typical sprayer attachment will swing around when set open if your not holding it.

    @SeaRat, I'll take a look at the link. Thank you. Although I suggested it, the shop didn't think it was necessary to replace the disc on my other tank. I'm going to go ahead and have them replace it next time I'm in.

    @gcarter I am not casting blame. I'm just curious if it would be prudent to secure tanks when filling. Probably not, since burst disc failure is so rare. The disc is certainly mine and my responsibility. I hope that part of my op didn't come off as if I was blaming the shop.
     
    Last edited: Jul 17, 2016
    mdb, gcarter, John C. Ratliff and 2 others like this.

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