Question Valve for 100% O2 Deco Bottle

[Lorenzoid]

I know of three guys that were burned. One of them is the current director of the WKPP, another is a large distributor of dive gear in the US, the third was a guest diver at a prominent cave system.

It happens, rarely, but it happens.

I know--I've seen you mention this before. But was the main cause of any of these incidents "opening the valve too quickly" or the fact that the threads were chromed?

I would guess that opening the valve quickly could be a contributing factor, but something else was likely the main factor, such as the reg not having been properly cleaned and lubed with O2-compatible lube.

 

[rjack321]

I know--I've seen you mention this before. But was the main cause of any of these incidents "opening the valve too quickly" or the fact that the threads were chromed?

I would guess that opening the valve quickly could be a contributing factor, but something else was likely the main factor, such as the reg not having been properly cleaned and lubed with O2-compatible lube.

There is no fire investigator ever capable of figuring the chrome vs unchromed question out. And combustible dirt/debris/aluminum oxide etc on a (combustible) nylon valve seat is going to exacerbate the potential for a fire. But figuring out all these factors after the fact is not possible for even the most adept NTSB level fire investigation. We know what increases fire potential, when one or more factors are present or elevated it's not possible to assign responsibility to any one thing. Fire, even more so with HP oxygen, is a multifactorial risk.

 

[arkstorm]

I'm obviously going to spend the extra $20 bucks for the designated O2 valve, but for my own edification, why is chrome finish bad ?

 

[Lorenzoid]

There is no fire investigator ever capable of figuring the chrome vs unchromed question out. And combustible dirt/debris/aluminum oxide etc on a (combustible) nylon valve seat is going to exacerbate the potential for a fire. But figuring out all these factors after the fact is not possible for even the most adept NTSB level fire investigation. We know what increases fire potential, when one or more factors are present or elevated it's not possible to assign responsibility to any one thing. Fire, even more so with HP oxygen, is a multifactorial risk.

So, in your opinion, take every reasonable measure that could plausibly improve O2 safety? Don't read this as me doubting what you said--my diving philosophy is indeed to take every reasonable measure to stack the safety odds in my favor. If switching my O2 bottles' valves out for DGX O2 Pros is in line with my philosophy, I won't hesitate. I just hadn't seen them mentioned before, that's all.

By the way, now that you mention the nylon valve seat, I am wondering why DGX did not include a less-combustible valve seat among the features of the O2 Pro? I know little about this stuff, but my understanding is that we don't see such a valve seat in regulators for scuba O2 use because the standard material (nylon?) is reasonably non-combustible, and an even less combustible material would be an expensive aerospace type, of which someone would then have to custom-manufacture valve seats. So I guess with the O2 Pro DGX decided on a compromise of an essentially standard tank valve with a couple of fairly straightforward but plausibly combustion-resistant features at a reasonable price point.

 

[rjack321]

So, in your opinion, take every reasonable measure that could plausibly improve O2 safety? Don't read this as me doubting what you said--my diving philosophy is indeed to take every reasonable measure to stack the safety odds in my favor. If switching my O2 bottles' valves out for DGX O2 Pros is in line with my philosophy, I won't hesitate. I just hadn't seen them mentioned before, that's all.

Yes take reasonable measures and do your best. But agonizing over one itty bitty factor like thread pitch and not cleaning your stuff regularly is tangential.

By the way, now that you mention the nylon valve seat, I am wondering why DGX did not include a less-combustible valve seat among the features of the O2 Pro? I know little about this stuff, but my understanding is that we don't see such a valve seat in regulators for scuba O2 use because the standard material (nylon?) is reasonably non-combustible, and an even less combustible material would be an expensive aerospace type, of which someone would then have to custom-manufacture valve seats. So I guess with the O2 Pro DGX decided on a compromise of an essentially standard tank valve with a couple of fairly straightforward but plausibly combustion-resistant features at a reasonable price point.

The problem is all the fluoro polymer materials (teflon and related analogues) which are potentially more O2 tolerant are too soft and will "flow" under 200+bar pressure in a conventional scuba valve.

Nylon isn't ideal from an O2 perspective but unless you completely redesign the way a scuba valve works, its the "best" seat material within the constraints of current designs.

 

[kensuf]

I know--I've seen you mention this before. But was the main cause of any of these incidents "opening the valve too quickly" or the fact that the threads were chromed?

I would guess that opening the valve quickly could be a contributing factor, but something else was likely the main factor, such as the reg not having been properly cleaned and lubed with O2-compatible lube.

I don't know that anyone called for an NTSB investigation of why the first stages blew up.

 

[Lorenzoid]

I don't know that anyone called for an NTSB investigation of why the first stages blew up.

Ha ha. No. But from what rjack said, it sounds like opening a valve too quickly and/or chrome on the threads, while never proven to be main causes of any accident, could plausibly be contributing factors, so it's worthwhile to use a reg that addresses those couple of issues if such a reg is available.

 

[mr_v]

Spend extra $20. I have those valves - they work well and I am quite happy.

 

[arkstorm]

Spend extra $20. I have those valves - they work well and I am quite happy.

That’s my plan. I’m glad to hear they work well too.

 

[mr_v]

So I guess with the O2 Pro DGX decided on a compromise of an essentially standard tank valve with a couple of fairly straightforward but plausibly combustion-resistant features at a reasonable price point.

It is a bit of a calculated risk. Material is one thing but you still need a heat source. Therefore, by making the valve slow-opening, DGX is betting that there will be a smaller chance of heat related-inflamation.