Double Your Burst Disk - Arguments For & Against, Please...

[alpaj]

I skipped to the end of the thread cause its a long one. I just wanted to put in that there was a report of a steel tank blowing (they attributed it to overpressurization) at 6000 psi ! Now I don't know that if you double up disks you double up bursting pressure (ie. 2 times 4000 psi BD = 8000 psi BD) you'd have to run tests on that. But in anycase it will probably be much higher then 6000 psi. That said I'd have no trouble with a doubled up BD cause for the tank to become the weakest link you asume the tank to be WAY overfilled by the filling station.

 

[Dive-aholic]

I haven't tested it, but I've heard doubling up disks doesn't double the burst pressure, it just essentially makes them ineffective as burst disks.

 

[NTDS]

There are burst disk police out there and they are called insurance investigators. You will see them going over everything with a fine tooth comb in the event of an accident in order to avoid paying out on your policy.
I wish you the best in your new charter business Steve but if you are publicly advocating breaking the law you are not going into business in a very sensible way.

Our business is not new we have been in business for years! I have filled thousands of cylinders. Funny the most recent fire involving scuba insurance adjusters on the island couldn't give a rat’s *** if they had triple discs in the valves or bolts.

A law question for you seeing that you are the authority on burst discs, when you owned your dive store did you check everyone’s burst discs before you filled the cylinders. If you did you must be some sort of god or you sure spent a lot of time and money changing out burst discs every time you cracked the disc assembly.

You seem to think that I’m in the scuba industry to make money I retired at an early age and don’t really need the money, it’s about lives and diving for me, if I believe that double discs can save a life then I will break the law every time.

Happy Diving

Steve

 

[Soggy]

The principle reason for the requirement for burst disks in the United States is to prevent tank explosions in the event of a fire, not necessarily to prevent overpressurization at a fill station, though this is a convenient side-effect.

I considered double disking/plugging for a while, but ultimately decided against it when I realized that it is not *my* life I would probably be endangering since I wouldn't be fighting the fire, nor operating the fill station and a burst disk failure at depth is not a life threatening failure if you are diving doubles and have a buddy, which I always do.

 

[wedivebc]

The principle reason for the requirement for burst disks in the United States is to prevent tank explosions in the event of a fire, not necessarily to prevent overpressurization at a fill station, though this is a convenient side-effect.

I considered double disking/plugging for a while, but ultimately decided against it when I realized that it is not *my* life I would probably be endangering since I wouldn't be fighting the fire, nor operating the fill station and a burst disk failure at depth is not a life threatening failure if you are diving doubles and have a buddy, which I always do.

Bingo! I think that is the bottom line

 

[Soggy]

b. A steel tank has never exploded (don't DD alums) and good luck finding the valve after a tank does.
.

You might be interested in taking the PSI Cylinder Inspection class. The first half of the class is a very interesting look at the types of cylinders out there and the history and causes of various explosions along with pictures. Many were aluminum, many were steel.

 

[in_cavediver]

I think GDI really hit the nail on the head with his post. In this day and age, you can slap a 300 bar manifold on LP tanks and use the 300 burst disks that came with the manifold and do cave fills. Double disking really isn't needed. I believe the double disks date back to times when you couldn't slap the 300 bar disk in a 200 or 232 bar manifold. Now, start a thread about not using right burst disk in you valve for your tank and see where it goes.....

For the record, I don't double disk, just use the appropriate disk for the fill pressures I use. I make no comment regarding the DOT stamping on the tank and relevent fill pressures however.

 

[SeanQ]

if I believe that double discs can save a life then I will break the law every time.

Would you do this even if it puts others at an even greater risk?

Whose life is seriously at risk from a blown burst disk? The fill operator is inconvenienced; it is the diver who finds themselves in a potentially dangerous situation. Regular valve maintenance nearly eliminates the problem. If it happens underwater by some freak occurrence it puts your gas management planning to the test.

Whose life is at risk from an exploding tank? The careless fill operator who left the compressor on (provided its safety mechanisms failed too) or a firefighter who is trying to save your building or, more importantly, your life.


The difference between the two is that the diver can do something about the situation because they should already prepared for gas problems while the person standing next to an exploding tank can only hope they don't get hit by anything. I know where I would rather be.

 

[Kim]

Ok guys. I have just edited a personal attack and removed references to it. Everyone is entitled to their own point of view but we don't allow flaming and other personal attacks on the board.

Thank you.

 

[Tommygun53]

Ive seen disks go for 2 different reasons. One was an overfilled tank, the second was a burst disk not tightened to specs.(80-100 inlbs on a thermo valve)

Now assume you have a 40cuft deco bottle that has been filled with 100% O2 to 3000 psi and the burst disk goes. I wouldnt want to be anywhere near that when it happens. No matter how clean the valve is!! I could see how some people would want to double disk a tank like this.

-Tom