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DIY Containment System Suggestions Needed

Discussion in 'Compressors, Boosters and Blending Systems' started by TN-Steve, Aug 20, 2015.

  1. TN-Steve

    TN-Steve Barracuda

    # of Dives: 200 - 499
    Location: Clarksville, TN, USA
    Hey gang,

    The shop owner where I work want's to put some type of a containment system in place at the fill station. I'm thinking of something like a large wooden box full of sand, with individual sleeves for the tanks to slip into vertically. The sand layer would be tall enough to come to the neck of a HP 120, probably some inserts to let 80's sit nicely.

    The idea would be that in the unlikely event of a tank letting go, the sand would act to tamp the forces, and direct most of it upward, where it not going to damage anything more important than the metal roof over the fill station.

    I'm drawing a blank finding any good info out there, how much sand to have around each tank, things like that. I'm confident enough in my wood butchery that I can build a structure capable of handling the weight of the sand, so that's not a concern. I just don't have a clue how much sand would be required to be effective, or if there are more effective designs I could take advantage of.

    Any suggestions, ideas or recommendations. Bonus points (redeemable for kittens at the end of the year) will be given for real life experience or working links to people who have documented designs on the web.

    Thank in Advance,

    fdarden likes this.
  2. cool_hardware52

    cool_hardware52 Dive Equipment Manufacturer

    Hard to beat a short section of heavy walled steel tube. One of our local metal supply houses, Industrial Metal Supply, often has a pallet of "drops" of heavy section metal tube. Wall thicknesses of 1" or greater. Easy to fab, easy to weld to etc.

    Not sure if there are similar resources in your location.

  3. diversteve

    diversteve always tired

    # of Dives: I'm a Fish!
  4. KWS

    KWS ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: SE TEXAS
    The purpose of the containment system is to isolate the tanks from the filling station. As you can see from both pictures, they do not do that. The operator does not want to be near the filling tank. If the tank blows the containment shields the operator from the blast. The water bath does next to nothing when it comes to absorbing the force of the tank blast. coolhardware52 has the right idea.

    bury these outside our filling area.

    PopCan station for easier SCBA cylinder refilling

    here is windy points containment system. other than being in the area of customers and the operator panel its good.

    Windy Point Park

  5. rcontrera

    rcontrera Dive Equipment Manufacturer

    It is FAR more dangerous to fill in a water bath than it is filling dry. If a cylinder is in a water bath and decides to let go, the force will be transferred through the water to the containment. Now, besides the cylinder blast itself, you have the shrapnel from the water bath itself.
    ti325v likes this.
  6. ti325v

    ti325v Dive Shop

    # of Dives:
    Location: Con Dao Islands Vietnam. Owner of Dive ! Dive ! Di
    I think the o.p. does not quite realize the force exerted by a cylinder letting go. Stick with the steel pipe, if you must butcher some wood, do it for concrete forms, and figure wall thickens at around 6 inches. ( Don`t forget the rebar ! ) You are gonna blow matchsticks and have a sandstorm with the proposed method.
  7. walkonmars

    walkonmars Solo Diver

    # of Dives: 200 - 499
    Location: Los Angeles
    A filling station with a jacket or barriers around tanks are a good idea but I feel the debris and flying small parts are more dangerous.
    Your original post seems that you are assuming the tank body is going to fail (linear tear/fracture or the valve threads fail at the top) and you are trying to contain the tank body parts. You may not be addressing that hoses, small valve parts, fittings, gauges and fasteners will be thrown around like bullets with any type of failure.
    I suggest possibly building a water tank or trough/tub to contain the tanks for filling. This has two purposes (cooling the tanks with fast fills and to contain the blast if a failure occurs. My feeling is that the tub material is NOT the primary barrier to the explosion or pressure release upon failure. You want to use the water around the tanks as the primary barrier to slow down debris. Your tubs can be plastic or just wooden barrels to contain a good 6 inches(or more) of water around the tanks (wood may become dangerous debris according to post by rcontrera). Also, the more water you have, the larger the protective jacket and more heat capacity to take up tank heating. Also, the more water, the less rise in water level when a tank is dunked into the tub. The tanks can be narrower in front and wider in the back so an operator doesn't need to reach back so far to place or take out a tank.
    More importantly is to maybe place a safe screen or poly-carbonate shield between the operator/customers and the filling station parts. I have had filling station operators and technicians tell me about hose and tubing failures that have caused piping to whip around fast enough to cut people up. One case, a copper tube broke loose and accelerated a 5 ft length fast enough to wrap itself around a 1 inch pipe.
    Place poly-carbonate screens between operators/customers and the filling stations. This can be a 4 foot tall, 2 foot wide barrier between fill area and the customers. You just walk around it to access tanks. Here in California, 3/16" and 1/4" thick sheets (2ft x 4ft)of cheap stuff is less than $80) from Industrial suppliers and cheaper from local hardware stores. I don't do this at home because I only fill my own tanks and I fill them very slowly at 1psi per second.
    Lastly, I always wear safety glasses (have 10+ pairs in the garage and house). Please make your operators wear them around the fill stations. Buy them nice looking types(popular brands) so they will want to wear them.
    Lastly, I think the steel pipe or tube is also a good suggestion to save space. All water bath suggestions have a problem with stagnant water that gets yucky. You can add some detergent or soap or drain it every few days. Another option is to just use a fountain pump and pump a small stream of cooling water to each place you have a tank to cool them. This may be a good option to cool tanks if you use the pipe option from ti325v and address the containment debris issue from rcontrera's post. On the other hand, there are some shops that fill tanks completely dry so the heck with my water suggestions.
  8. TN-Steve

    TN-Steve Barracuda

    # of Dives: 200 - 499
    Location: Clarksville, TN, USA
    Thank you all for your comments, I'm learning a lot. Right now I've got a source for some 3/8th steel pipe 10 inches in diameter for a low cost. Now I know that in itself won't be enough to "contain" the blast if a tank lets go, but that's not the primary purpose. Let me give you more info, and lets see where this goes.

    Right now we have our compressor / panel and bank bottles inside a large trailer. The trailer is on a cement pad behind the shop, with a metal roof protecting it from rain. The entire back behind the shop is bounded by chain link walls and a metal roof. We are currently filling tanks inside the trailer. The plan would be to run the fill whips through an opening in the side of the trailer and then have the containment system outside, so that any blast would basically be directed upward toward the metal roof over the fill station. The operator would be inside the trailer during the fill operations, the tanks outside. (as opposed to now, where I'm basically standing right next to / over them)

    Now I'm thinking the 3/8th steel, set inside large plastic water barrels, with appx 6 inches of packed sand around each of the pipes. That should help contain the initial force, disperse it, and let it go upward where it won't do any damage.

    The other plan that has been floated is for a 3/8th steel open top box, with chains secure the top of the tanks during filling. The box would have a sloped front on it to help load tanks, and the end joints welded with angle strips the entire length to strengthen them. One of our instructors is part owner of a dive op in PR, that's what they use. I'm not sold on it, since the lower opening would make a place where shrapnel and blast could hit someone, and that would also be directed directly at the back wall of the shop based on where it would be located.

    Keep the ideas coming.


  9. descent

    descent Solo Diver

    What you're trying to design is like a grenade sump, only bigger.

    Here's a blast wave / overpressure damage table from NOAA.

    If you take your final design out to the county demo range to test it, please do share the Youtube link with us.
    TN-Steve likes this.
  10. KWS

    KWS ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: SE TEXAS
    It just wont work. Pardon me if i appear to speek down to you, I am not trying to do so. Ther is no difference in water and ground. dive 3 ft of a board in a pool and the water slows your fall because it reshapes itself to accomodate the new matter trying to occupy its space. . hit the water after falling 10 stories and the water (unable to reshape its self fast enough) is concrete cause it can not change shape as fast as required. Ther is a point where any fluid ceases to absorbe and begins to transfer energy. similar to using a chisel on a bolt. hitting the chisel with a hammer tranfers full force to the bolt. if you blow a tank in a water bath there is no absorbntion,,, it is only additional flying stuff. to some degree the water becomes an extension of the tank itself. What is needed is a method for channeling the explosion in a mannor that allows a limited controlled release direction of the energy. a tank in a pipe becomes a shaped charge of sorts where the release is channeled in a chosen least destructive direction. That is normally up. The containment does not absorb it channels the release. There for to allow this to work the operator has to be in a position that is not in the vacinity of or in the path of the release energy channel. Your compressor is in one space and the tanks being filled is in another space. (the containment space) a concrete bunker if you will. A 10x10x10 concrete room with pipes in the ground for housing the tanks. The pipes protect the adjacent tanks from direct horizontal impact and causing a chain reaction of explosions. the bopnker volumn of air space absorbs the air compression of the blast and the walls of the room contains / confines the fragmentation of the tank. The tanks are not supposed to be in the imediate area of the fill station operator controls. Tanks are hazmat. Actually the hgh pressure is the hazmat. The tanks contain hazmat. there are procedures for the handling and the release of hazmat, even in scuba. Your precautions. water is just like steel with that energy behind it. googles. wont protect you from the debris of an explosion, al they do is provide a barrier from an air LEAK in the fill station components at best. You know like putting on the whip turning on the air and finding the vent is open still. There is a tremanduos amount of energy/force in a pressure vessel. One can only begin to appreciate it when a burst disk goes and you spend some time chasing your tank till it (pardon me) runs out of gas. And that is IMO an controled release of energy.


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