Scuba Cylinder kills fire fighter

[Rred]

'Waiting for it to fail instead of replacing on schedule is very much "penny wise and pound foolish" in my opinion."
Totally agree with you. However, the rated life cycles of a plain copper burst disk, which may experience 1000 cycles in one year of commercial use (and the tank is designed for over 10,000 to meet DOT specs) is more than most spot divers will do in then years.
This is why I prefer separate copper discs. The pressure cycling means nothing. What gets to them is any salt water that is left in the outer surface of the disc, in the plug side, and any moisture which gets to them from the tank side.
I coat many things, including burst discs, with a thin film of Krytox grease. That's chemically inert (against sulphur, flourine, oxygen, and acids) from -70F to 700F, and does not migrate. It makes surface impervious to all contaminants, It also makes Crysotolube and the other normal "for oxygen service" lubricants seem dirt cheap.
I've also used it to lube combustion gas cylinders, where everyone in the business says "You can't lube them, the gas is too hot. You just have to decarbon them to clean them." Well, no. A parsimonious film of Krytox and all the carbon just wipes off with a paper towel.(G)
Damned expensive stuff, and worth every penny.

 

[Bob DBF]

'Waiting for it to fail instead of replacing on schedule is very much "penny wise and pound foolish" in my opinion."

Especially if it goes off in your vehicle and blows out a window or two. Bad enough if it goes off when you are around and have to then explain to your wife why you crapped your pants, the up side being that you may not be able to hear her laugh.

I change mine at hydro, I instituted that procedure a few decades ago after an incident.


Bob

 

[TrimixToo]

Especially if it goes off in your vehicle and blows out a window or two. Bad enough if it goes off when you are around and have to then explain to your wife why you crapped your pants, the up side being that you may not be able to hear her laugh.

I change mine at hydro, I instituted that procedure a few decades ago after an incident.


Bob

I can tell you from unfortunate experience that a blown burst disk will not blow out the windows in a closed vehicle. (The experience was unfortunate because the tank in question was full of trimix! And the damn disk was only a year or two old.) Exhaust vents are an integral part of the car's HVAC system. Usually if not always located in the rear, they are more than large enough to prevent any pressure buildup inside.

 

[IDNeon357]

What is the typical pressure in a cylinder used for firefighting? 3000 psi seems like overkill for surface breathing, maybe scuba tanks are more pressurized than the ones they were used to working with?



@fsardone can you give us more information about the different tanks shown in the video? The last 2 tanks were obviously less reactive to the loss of the valve, were they at lower pressures?

Up to 4500 psi, actually, usually for compact composite bottles since you want smaller/lighter bottles for obvious reasons but need a lot of air in them.

I seem to remember a pressure for steel was 2700psi, but composite is going to be 4500 to 5500psi...

You're lucky to get 15 minutes of work with even that, here's the estimates.

30 minute cylinder = 45 cu ft.
45 minute cylinder = 66 cu ft.
60 minute cylinder = 88 cu ft

Reality is half that usually...that's a modest breathing regime.