Aluminum K-valves

[KevinNM]

They were so much not at fault that they were banned. Try to buy a new Al med regulator today. (in the US. The Chinese will gladly sell you one.)

Essentially you can get Al to ignite in 100% easily. Brass is much harder. So with improper cleaning you get a flash fire in a brass reg that at worst burns up the valve seats and extinguishes itself when it runs of out fuel. Sucks to be you if you are breathing from it then, but it's a contained problem. With an Al regulator the regulator body also catches fire and you get the multi-foot long blowtorch coming out the regulator that burns until the tank ruptures or the oxygen is exhausted. Or the regulator cannonballs off and the tank vents and the added O2 turns the already bad fire into a special little corner of hell.

 

[guruboy]

And somehow the tank itself is immune to burning?

 

[KevinNM]

No, that happens too. There was a case a few years ago with a tech diver whose deco tank internally ignited and blew up inside his house, apparently when he dropped it. It is much rarer that the flurry of med gas o2 fires that caused the report.

 

[Luis H]

That is a Voit valve from the early to mid 1970’s. Aluminum cylinders were introduced into the scuba industry in 1972 and a few years later Voit decided that it would be a good idea to make a valve to match.

Voit/ Swimmaster, introduced that valve and advertised it as being specifically compatible with aluminum cylinders. I remember the advertising and the catalog pictures as mentioning that it avoided the contact of dissimilar metals. I can’t remember if it claimed that it avoided galvanic corrosion or any other specific detail.

The O2 related posts have nothing to do with that valve. In the 1970's no one in the scuba industry was promoting the use of O2 or any type of high O2 gas mixture. Some regulator used to have labels that read: “USE COMPRESSED AIR ONLY”

 

[guruboy]

Cool. Thanks, Luis.

 

[2airishuman]

And somehow the tank itself is immune to burning?

Experience, in the medical oxygen world, is that the cylinder itself is less likely to be exposed to enough contamination and an ignition source.

Three counterexamples come to mind, though. The one mentioned upthread, an explosion while filling with contaminated whips, and the medical o2 tech who tried to remove a seized valve that wouldn't open.