Show and tell at the ER

[iamrushman]

interesting story and thanks for sharing...

 

[TMHeimer]

I tell my students not to use the tank air technique to dry the cap. It can inject water into the first stage if you are not holding it correctly and most of all its annoying as hell to others around you. A towel or tshirt does a better and quieter job.

I hold it correctly and also use a towel (I don't rinse with the reg on the tank, so I want to dry it best as possible). There's usually nobody around to annoy. I don't recommend it to students. Then again this is Advanced Forum.

 

[freename]

I figured I should drop by and give a quick follow-up - and reply to a couple comments while I was here!

You have the crackles for about 24 hours.

I should've just posted on here instead of going to the ER - great estimate! (Nah... I still don't regret my ER trip...) I'd say that the hand officially deflated (or at least, lost its bubble wrap feel) a little over 24 hours after the fact.

And of course, I should clarify: I in no way had any issue with becoming show and tell!

Am I a bad person because I chuckled when I read it?

For the record, nor do I have a problem with it being laughed at on here - I found, and still find, the entire thing greatly amusing! Had I realized that others could feel it too, I probably would have also gone around to show off to my coworkers before heading to the hospital... ahh well, next time! As I said, it needed to be shared...

A rug or thick towel does wonders to deaden the sound of escaping air

Great idea, thanks! Of course, I'm not sure I'll think of it next time this happens. There's something about the shock of being woken at 5 AM to the sound of extreme static that makes it... rather disorienting.

I carry a card in my wallet that has special instructions to medical personnel due to my day job as a waterjet operator.

Having stumbled my way into this experience, I'm actually rather curious what sorts of instructions such a card may have. I don't suppose you'd be willing to share?

Did DAN cover the injury??

Ha! Believe it or not, as I sat in the waiting room I pondered to myself whether or not they would have been worth calling... you know, had I carried their insurance! As it happens, I was/am actually planning on getting it at the start of January before a dive trip. Ah, fortunately healthcare in Canada is free...

I would never approach a leaking tank. There is nothing you can do to fix the problem and there is always the possibility of the situation going from bad to worse (as you found out).

Alas, I was worried about my other dive gear... some brand new things, too, bought for the aforementioned trip... and located very close to said tank. I'd imagine my landlords probably wouldn't like it, either, if the air jet messed up the wall. I wisely chose to risk my health and welfare to save material possessions, as any proper consumer would! Ha!

How long was your hand in the line of fire? I assume not very long?

Yep... not long at all. I can't tell you exactly how long, or when the injury took place - whether it was in pulling the tank out, or locating the leak, or figuring out what to do about it... but I'd say a couple seconds at most. And the interesting thing is that I didn't even notice it at first. It was just that I happened to glance at my hands and something unusual caught my eye. I can imagine it would be rather simple for the inflation to have continued, say, idly standing beside it with my hand on the valve - except for the fact that it got rather cold, and I'm not a fan of holding onto cold metal objects bare handed.

Even if the seal failed instantly around the entire perimeter of the O ring the initial pressure of the escaping air, at some minimal distance, will be tank pressure. Based on the time for the tank to completely empty (or for the leak to become nearly silent) I'll figure the mishap happened when the pressure was perhaps 60% or more of what it was before the leak started. Let's figure 1500psi or so.

I'm sure there's a simple formula for how the pressure decreases. Other than figuring an initial distance from the source, it may be as simple as the inverse square law - at twice the distance the pressure will be reduced to 1/4. That would only apply when the escape path is unobstructed, as any kind of confinement will reduce the rate of pressure decrease. Especially if the leak is limited to a small portion of the O ring I can easily imagine a jet of air with a pressure of a couple hundred psi if you put your hand fairly close to find the source.

... I am phenomenally tempted to go dig out one of my textbooks on fluid mechanics right now... off the top of my head, I'd think that the Bernoulli equation should work: an essentially laminar flow out a "pipe," z1 would be roughly equivalent to z2 and cancel out... but wait, would the injury be from the pressure or the velocity? Do we assume P1 in the vessel and P2 as atmospheric outside... are we solving for v2 or P2? Pressure would make more sense, being P=F/A... and I could measure the size of the area by the "puncture wound"...

... I had a date the other day with a doctor of physical chemistry. We ended up talking about fluid mechanics and its application in aerosols.

I think I have a problem.

I'll see your frostbitten hand and raise you some hearing damage

... ow. No, you can keep your hearing damage. I fold. Hearing the tank go in the confines of my apartment was bad enough; I can't imagine what you experienced - no... no, I can imagine it... I just don't want to!

Fun fact... I've lived in this apartment now for... almost 2 years. And I've never met my neighbor. Well, as fate would have it, the following day I got into the elevator with 3 other people. They hit the button. My floor. A rare occurrence, but it has happened before. It climbed to my floor, we got off. We started walking the same direction. I thought to myself, "wouldn't it be funny if these were my neighbors?"

... until they started unlocking the door next to mine. (My other 'neighbor' would be the elevators). So yeah... I paused for a moment, and then turned to them and said, "I have to apologize if my tank woke you up this morning" and we discussed the burst o-ring for a bit. I think the one person was a diver, since he asked me if it was on my regulator... but yeah, I am pleased to report that my tank did not manage to wake the neighbors.

 

[Storker]

... I had a date the other day with a doctor of physical chemistry. We ended up talking about fluid mechanics and its application in aerosols.

I think I have a problem.

That's just quite ordinary geekiness

 

[tstormdiver]

I tell my students not to use the tank air technique to dry the cap. It can inject water into the first stage if you are not holding it correctly and most of all its annoying as hell to others around you. A towel or tshirt does a better and quieter job.

I can second this. As a repair tech, I frequently see the internal HP parts of regulators pitted & corroded, from where the customers have used cylinder air to dry their dust caps & yoke nuts, thus inadvertently injecting salt water past the filter into the high pressure chamber.

 

[muddiver]

This reminds me of the stories by my submariner and steam ship powered buddies that talk about walking watch while singing a broom stick in front of themselves. It is a common occurrence for mechanics in the steam power industry to loose digits to unnoticed pinhole steam leaks.

I do find it unusual that you managed to hold any portion of the cylinder closely enough to become embolized. Rile one: check leaks from a distance until localized.

Sorry for your injury.


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[Nuribromanski]

thanks 4 sharing! could have been worse, 2!

 

[Centrals]

Didn't you take any picture?

 

[tech_diver]

a couple of random thoughts...

Over the years, I have seen neck O-ring and burst disks spontaneously fail without cause or reason on a few occasions. Just like the stories told here, it can just randomly happen while a tanks sits. It is very rare but I keep it in mind every time I plan an advanced dive.

Also, those who are interested might look at the pneumatic hypodermic technology being developed. You actually can inject yourself with high pressure air.

 

[maj2]

Also, those who are interested might look at the pneumatic hypodermic technology being developed. You actually can inject yourself with high pressure air.

"Jet injectors" have been around for a while, falling both into and out of favour over the years. Agreed though that it is still developing and a very interesting area.

I was on a charter once shortly after getting certified. This charter was probably 12-13 years ago. It was never suggested to me duration training to open the valve to dry my dust cap, but my buddy had been taught to do it. Once the captain heard the tell-tale noise, he came over to see what it was and specifically mentioned subcutaneous emphysema as a potential risk associated with the practice. I still do not engage in the practice, but never really gave the warning much thought again until reading this thread.

Interesting thread. Thanks to the OP for sharing!