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

[JS1scuba]

Well, I've *seen* several dive days ruined by having burst discs blow at inopportune times for no apparent reason.. yet I've never even *heard* of a modern steel tank blowing up due to overpressurization.

*shrug* I don't, and I won't, but to say that it's incredibly dangerous is a bit of a stretch, I think.

With more than 5000 personal dives, and more than observing 10 times that amount over the years and having filled over the years close to 100,000 cylinders
I have seen less than a handful of safteys release. These were normally in hot tropic zones where valve maintenance is at best poor.

Service the valve on regular intervals, replace the saftey with the properly rated saftey and your perceived problem will not exist.

 

[pusser]

Well, I've *seen* several dive days ruined by having burst discs blow at inopportune times for no apparent reason.. yet I've never even *heard* of a modern steel tank blowing up due to overpressurization.

*shrug* I don't, and I won't, but to say that it's incredibly dangerous is a bit of a stretch, I think.

In the event of a fire the burst disk prevents the tank from exploding due to high pressure and heat. You may not care but the fireman who is trying to save you and your stuff might.

 

[dherbman]

In the event of a fire the burst disk prevents the tank from exploding due to high pressure and heat. You may not care but the fireman who is trying to save you and your stuff might.

Good point.

 

[jonnythan]

In the event of a fire the burst disk prevents the tank from exploding due to high pressure and heat. You may not care but the fireman who is trying to save you and your stuff might.

So.. use them in case they get caught in a house that's on fire?

 

[dherbman]

So.. use them in case they get caught in a house that's on fire?

Or a car that's on fire.

Use them because it's the law. If you don't use them, understand that the decision may impact more than yourself and be prepared to be held accountable.

 

[Dive-aholic]

...Except as provided in paragraphs (f)(5) and (f)(6) of this section, a cylinder filled with a gas and offered for transportation must be equipped with one or more pressure relief devices sized and selected as to type, location, and quantity, and tested in accordance with CGA S-1.1 (compliance with paragraph 9.1.1.1 of CGA S-1.1 is not required) and S-7. The pressure relief device must be capable of preventing rupture of the normally filled cylinder when subjected to a fire test conducted in accordance with CGA C-14 (IBR, see § 171.7 of this subchapter), or, in the case of an acetylene cylinder, CGA C-12 (IBR, see § 171.7 of this subchapter)....

Not commenting on the practice in particular, but DOT only governs cylinders "offered for transportation". I believe this refers to commercial operations conducting interstate transports. I don't think there is a legal issue for privately owned cylinders for personal use.

 

[Rick Inman]

So, let's say you put a 5000psi disk into a LP tank with a plus rating to 2700. Now there's a fire in the house all around the tank. Are we saying that the tank will explode before the 5000psi disk blows??

What about the o-ring in the tank neck?

 

[dlegros]

I may be way off base here, and maybe Joel has something when he says that European cylinders are different (he does seem to know his ***** )

But Burst disks are alien to us in the UK and we don't have exploding cylinders (99% steel - Faber, Heiser or ECS) all over the place.

Dom

 

[wedivebc]

So.. use them in case they get caught in a house that's on fire?

Or use them because;
a. it's the law
b. in the highly unlikely event a tank should blow up. The widow of the poor tank monkey who agreed to overfill the tanks is left penniless because the insurance is void because the investigator found doubled burst disk.
c. because there could be any number of other eventuallities that you may not see but because of a. the pitfalls are probably numerous.

I have filled thousands of tanks and never seen a burst disk fail.

 

[dherbman]

Or use them because;
a. it's the law
b. in the highly unlikely event a tank should blow up. The widow of the poor tank monkey who agreed to overfill the tanks is left penniless because the insurance is void because the investigator found doubled burst disk.
c. because there could be any number of other eventuallities that you may not see but because of a. the pitfalls are probably numerous.

I have filled thousands of tanks and never seen a burst disk fail.

I've filled several thousand and have seen two fail. One during a fill and one after.