Need help identifying VOIT Steel tank size

[JamesBon92007]

With a 5000 psi burst disc you'll usually reach the yield strength of the cylinder wall before the burst disc blows.

That's probably going to hurt. What "service pressure" should I be using? I was finding the burst pressure on some of the disc sets that I was looking at but others only had the service pressure. What is the burst pressure for a typical AL 80 rated for 3000 psi?.

 

[runsongas]

i use 2400/4000 psi discs. the 2400 disc will blow at 3600 to 4000 psi vs 3375 to 3750 psi. the point to keep in mind is that lp72s are fairly old tanks at this point and while the burst pressure when new would have exceeded 5000 psi, that may not be the case anymore and the only value to be sure of is that it passes the hydro pressure at 3750 psi. as the margin between 4000 psi and 3750 is fairly small, the risks are generally low in swapping to the newer lp discs.

 

[John C. Ratliff]

I deal with transportation of co2 tanks in many of my projects at work and DOT rules (and mythology) come up a lot.

I will just say this... chances of being pulled over by the DOT are practically zero, and chances of them inspecting your burst disks is even less than that..

True, but that's not the point. If a person consciously uses the wrong burst disc, or "doubles" them to fill to a higher pressure (or actually plugs the port, as reported here on other threads), and something bad happens (tank explosion), there will probably an investigation. If that investigation shows that this person subverted the regs or the manufacturer's recommendations, then there is the potential for personal liability and/or loss of insurance monies for the accident. I used to work for a workers' compensation insurance carrier, and conducted a number of accident investigations of both fatalities and SDIs (Serious Disabling Injuries). While workers' compensation is a "no fault" insurance (the worker is covered regardless of fault), the insurance company will go after anyone with "third-party liability" for the accident, and seek reimbursement. That concept could apply here if an accident occured at a dive shop, or to a divemaster paid to do a job. As a Certified Safety Professional, I know that these things can happen.

This came up in a forum where someone who probably is not aware of the specific information on these tanks was presented the idea of intentional overfills as if it were done as a matter of good practice, which it is not. That is the context in which I presented this information.

SeaRat
John C. Ratliff, CSP, CIH(2006-2017), MSPH

 

[TrimixToo]

I put the right burst disks in my LP72s. The closest ones are 4000 PSI. Someone mentioned the tank failing first. This is why you don't store AL80s partly full. If you have a fire...

 

[Caveeagle]

How do the Europeans survive without burst disks? **sarcasm**

 

[John C. Ratliff]

We also discussed this at length in 2015 at the Vintage Scuba Supply website:

http://vintagescuba.proboards.com/thread/3671/burst-disk-plug

SeaRat

 

[2airishuman]

That's probably going to hurt. What "service pressure" should I be using? I was finding the burst pressure on some of the disc sets that I was looking at but others only had the service pressure. What is the burst pressure for a typical AL 80 rated for 3000 psi?.

For 3AA and 3AL cylinders, the proper burst disc is 5/3 the service pressure, which is the number after the "3AA" or "3AL." So, for AL80s, 3AL3000, it's 5000 PSI.

How do the Europeans survive without burst disks? **sarcasm**

There is much greater attention to controlling the pressure on fill whips and having pressure relief valves on the fill side.

I'm not necessarily a big fan of the U.S. system, but you do have to look at the system as a whole, because the problem of overfills does have to be addressed somewhere or there will be catastrophic accidents.

 

[JamesBon92007]

For 3AA and 3AL cylinders, the proper burst disc is 5/3 the service pressure, which is the number after the "3AA" or "3AL." So, for AL80s, 3AL3000, it's 5000 PSI.
.

So, is the burst disc always the same pressure as the hydro test pressure? For a 2250/72 it's 5/3 for the hydro, but is it the same for aluminum?

 

[John C. Ratliff]

5/3 x 2250 psi = 3750 psi
5/3 x 3000 psi = 5000 psi

SeaRat

 

[captain]

Burst pressure of a steel 72 is in the 8000 to 9000 psi range. No shop compressor is capable of that. Fire exposure is the primary danger. It raises the pressure and weakens the steel. The burst disc is rated to blow before the steel is substancially weakened in a fire.