Scuba tank problem

[netdiver]

It probably would not have ruptured underwater. Key word here: probably. Had it ruptured, you surface RIGHT NOW or you drown. It's that simple.

Really bad advice!!! Do not shoot to the surface. Follow your training. Take the last few breaths from the cylinder as it expels air and swim to your buddy <or the closest diver to you> to use their octo <alternate reg>.

Contrary to some posts and common belief, the increased pressure from the heat of the sun was not the cause and is at most only a minor factor. If the tank had been filled at approx. 80* and the tank was 140* in the sun, its pressure would have only increased by 333 PSI. Of course, this might be enough to push a bad disc over the edge but eventually this would've happened even at normal working pressure as the disc continued to disintegrate. If it was a disc....

How long did it take to empty?

 

[piffle]

I did see a burst disc let go on someones back while they were in water. I was doing my pool work for ow in Feb. in Misouri. It was like 15 degrees that night and they brought the tanks over to the indoor pool in the back of a pickup truck. While we students were gearing up, one of the guys assisting with the class geared up and jumped in the heated pool before any of us and the disc burst. It freaked everyone out to see and hear this thing blasting at the base of this guys head.

 

[h90]

The burst disc burst. Sounds to me like the tank got hot and overpressurized, so the burst disc let go. Don't worry--not your fault. Maybe the tank was overfilled. Maybe it was a black tank and sat out in the sun while the pressure built up inside it and it overcame the burst disc.

This is, believe it or not, a good thing; had the disc not let go, the tank itself may have ruptured, and you (and all around you) would have had a VERY BAD DAY. Every tank valve has a burst disc installed. At least, it's supposed to.This is a safety feature designed into the valve to prevent tank overpressurization. It should be rated at 5/3 the tank's working pressure. If a tank has a 3000psi working pressure, it should have a 5000psi burst disc installed in it.

It probably would not have ruptured underwater. Key word here: probably. Had it ruptured, you surface RIGHT NOW or you drown. It's that simple.

Burst discs are not common in every country. But it is a good idea to have it.
Actually every overfilled tank should be able to stay the heat of the direct sun, but I recall that I say 2007 a tank with "next inspection 1995" (Thailand) so better a corroded burst disc fail than the tank.

 

[SkydiverChick]

Was a Burst disc that let go, its a built in safety device to prevent high pressure mishap's, since it is usually considered to be good practice to self check any tanks you rent or pick up, what was the pressure on it when you picked it up?and what kind of tank AL or steel?
let me guess you had it sitting under the hot sun after being moved in a hot trunk right? while it should not have let go, it could have been a bad disc that should have been replaced when it was serviced, or the tank was already filled well over service pressure then sun baked till the pressure built up to crazy levels. I am sure some of the others can guess assuming standard rental of a Al 80, 3000 PSI normal fill, pressure was guessing around 3600 to pop the disc.

No, it wasn't in a hot trunk. My husband has a remote start on his SUV and starts it up a few min before getting in to give it time to cool down. The tank was then put on the back deck of the boat which has a soft top on it and secured under a bait table. It was hot out (FL) but no way was the sun shining on the tanks or even the deck. It was filled to 3000 PSI but surprisingly it only took at the most a minute to empty. I mean I've never seen one blow before but I just assumed it would take a little longer.

 

[SkydiverChick]

Really bad advice!!! Do not shoot to the surface. Follow your training. Take the last few breaths from the cylinder as it expels air and swim to your buddy <or the closest diver to you> to use their octo <alternate reg>.

Contrary to some posts and common belief, the increased pressure from the heat of the sun was not the cause and is at most only a minor factor. If the tank had been filled at approx. 80* and the tank was 140* in the sun, its pressure would have only increased by 333 PSI. Of course, this might be enough to push a bad disc over the edge but eventually this would've happened even at normal working pressure as the disc continued to disintegrate. If it was a disc....

How long did it take to empty?

I discussed it with the other dive and we both agreed that's what we would have done and will do in the future if it were to happen again. I would say it took about a minute to empty.

 

[captain]

The burst disc burst. Sounds to me like the tank got hot and overpressurized, so the burst disc let go. Don't worry--not your fault. Maybe the tank was overfilled. Maybe it was a black tank and sat out in the sun while the pressure built up inside it and it overcame the burst disc.

This is, believe it or not, a good thing; had the disc not let go, the tank itself may have ruptured, and you (and all around you) would have had a VERY BAD DAY. Every tank valve has a burst disc installed. At least, it's supposed to.This is a safety feature designed into the valve to prevent tank overpressurization. It should be rated at 5/3 the tank's working pressure. If a tank has a 3000psi working pressure, it should have a 5000psi burst disc installed in it.

It probably would not have ruptured underwater. Key word here: probably. Had it ruptured, you surface RIGHT NOW or you drown. It's that simple.

While it sounds like a burst disc it wasn't because the tank was hot. It would take throwing it in a fire to gain enough pressure to blow a burst disc. Most likely it wasn't replaced in a while and corrosion weakened it.

 

[UCFKnightDiver]

+ 1 for double disks?

 

[DA Aquamaster]

I normally advise against doubling the burst disc. Burst disc aseemblies and the burst discs themselves are not designed to work that way and they get bent and stressed when doubled in a manner that can actually precipitate a rupture. it's one of those ideas that sounds good but really isn't.

If you are worried about a failure, replace the disk annually or bi-annually just to ensure it is in good condition. When replaced at reasonable intervals (at least every 5 years) burst disc failures just do not happen. Since I do get 3600 psi cave fills in Florida, my 2400 psi doubles have 3500 psi service pressure burst discs in the manifolds to reflect the actual working pressure rather than the "turn pressure" stamped on the shoulder. Otherwise a 2400 psi service burst disc is designed to rupture at between 3600 and 4000 psi so the margin is way too thin to non existant with a 3600 psi fill.

If for some unknown reason (probably related to paranoia, OCD or just ignorance) the risk of a burst disc failure still bothers you, put a single disc in it designed for a higher service pressure. Burst discs can be found for up to 4350 psi service pressures - giving a burst pressure of 6525 to 7250 psi - and that is better approach than doubling the discs in your 2400 to 3500 psi tank. A derivative of that approach are stainless steel discs that are intended to disable the burst disc function and prevent a rupture along with reducing much of the corrosion that would occur with a traditional copper disc.

Doubling a burst disc is the last option I'd consider as I have seen ruptures caused by this practice.

 

[DandyDon]

I think leaving the standard disc is fine as I'd hate to have a burst pressure of 6525 possible. Much rather see the disc go than risk doing that to a tank if something went awry.

The burst disc is actually on the valve right? One of the plugs...?

 

[frankc420]

Looks like you have your answers already. I have yet to see a tank empty due to a valve O-ring, but I suppose anything is possible.

It takes 1 to 1.5 minutes for a tank to empty when the burst disc blows.