tank failure

[lermontov]

Hi I'm new to scuba diving and reading about gas management and an example in the TDi manual asked for calculations to work out what two divers could do if one had a complete tank failure., but my real quest ion is how often does this really occur? I've tried to search on the internet about accidents re complete tank failure but can find any -so how common /rare is it/

 

[Centrals]

Complete tank failure is quite rare.
It has nothing to do with gas management, it is about equipment maintenance.

 

[DevonDiver]

Tank failure.... or a general equipment failure that ceases effective gas supply to the diver?

Tanks don't "fail" often; but you do hear occasional reports of debris blocked valves, blown valve o-rings or, more commonly, leaks from the valve handle. These are all servicing and maintenance issues.

In respect to wider failures, there are many. It can be something as simple as a torn 2nd stage diaphragm, a mis-aligned mushroom valve, hose blockage, 1st stage IP drop, a yoke-valve getting forcibly jolted to misplace the o-ring... etc etc etc...

In more than 2 decades of diving, I've only had to deal (air-share donor) with one true out-of-gas emergency caused by an unanticipated equipment failure (double regulator hose failure... read the report HERE). Other than that, I've only had to donate gas in training exercises or as a pre-emptive action to prevent someone running low on gas.

 

[tstormdiver]

As the others have mentioned,... complete failures are very rare,... However when in a technical overhead environment, whether real (wreck or cave) or virtual (decompression obligations), gas is typically planned for the worst case scenario. Yes, it can be taken to silly extremes, but when you can not get immediately to the surface,... you want to have plenty of gas to get you home safely. That is why it is addressed in the TDI manual.

 

[dumpsterDiver]

[video=youtube_share;Bap2PxetarQ]http://youtu.be/Bap2PxetarQ[/video]

I filmed my failure a few yrs ago. Pretty rare.

 

[2airishuman]

Minor leaks at the attachment point between the valve and cylinder are common but are not sudden or catastrophic. They can be identified early in the dive. Otherwise, here are some of the actual reports I've seen of failures in the water:

1) O-ring failure at the sealing surface between the tank valve and the regulator. Not uncommon. This is a problem particular to yoke valves, never heard of it happening with DIN. Usually happens at the very beginning of a dive, but DumpsterDiver reported an incident of this type at depth. [ETA: crossposted, this is the incident DumpsterDiver reports upthread]

2) Clogged dip tube. I've only seen one report of this. It was unclear to me how the tank accumulated enough particulate contaminants to pose a problem.

3) O-ring failure between the tank valve and cylinder neck. Cause unclear in the reports I've seen although I have trouble imagining how it could happen without the wrong parts or insufficient assembly torque.

4) Burst disk. Can fail as a result of a history of overfilling the tanks, or as a result of excessive assembly torque. I've seen one report.

5) Valve stem seal failure. Not uncommon on older valves. Some shops replace all the valve O-rings at the annual tank inspection, which I think is prudent.

 

[Mustard Dave]

Tank failure is incredibly rare, but you should be prepared for any situation where your kit is no longer able to supply you with gas, so good buddy contact and/or redundant gas sources should always be at the top of the list.

2) Clogged dip tube. I've only seen one report of this. It was unclear to me how the tank accumulated enough particulate contaminants to pose a problem.

One of the lads from my club had this in Cuba many years ago (where their attitude to equipment maintenance is somewhat poor. He went head down for a moment, went to breath, and nothing. It did not help he was a good distance away from any of the others in the group.

 

[Dive Right In Scuba.]

I don't know which TDI manual you read to learn about the problem, but you should understand that TDI is what is known as a "technical diving" agency. Their recreational or sport diving equivalent is SDI. There is an important difference. Technical divers must prepare for dives in which they cannot go to the surface to solve a problem, either because they are in an overhead environment or because they have mandatory decompression obligations. they must have a much greater concern about such problems than other divers will.

If you are a new diver, you should not be in such a situation, and your options are very different. An open water, recreational, sport (choose your term) diver should always have the option of going to the surface in relatively short order. If your tank is leaking air, you should have no trouble doing it by yourself. If you have a sudden gas loss, you should have a buddy nearby with whom you can share air during that ascent. If not, you were taught how to get to the surface by yourself in such an emergency in your OW class.

 

[abscuba]

It does happen, but as it has been stated multiple times. Hence why you always dive with a buddy unless you are trained and equipped to dive solo. TDI does go into the weeds a lot more because on the tech side you are self reliant and the rare things tend to happen more when you are in a place where it is harder to deal. That is why tech divers always have redundant systems. Things do happen I seen a tank valve have a catastrophic failure, I have had a complete regulator failure at depth as well, but being prepared is what makes them just stories instead of insurance statistics. It is good as a new diver you are studying, but be mindful of what you adopt out of tech manuals as there is training that goes along with those manuals and they are designed for experienced divers going beyond what is done in recreational diving and can get you in trouble if it is outside of what you are trained to do. But always keep learning.

 

[DogDiver]

4) Burst disk. Can fail as a result of a history of overfilling the tanks, or as a result of excessive assembly torque. I've seen one report.

This is the rational as to why most cave divers "double disc" their valves. [emoji41]



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