Most common open-circuit equipment malfunctions leading to problems?

[Bob DBF]

I find it hard to call something an "equipment malfunction" when it's due to the owner not properly inspecting, maintaining/cleaning, etc. Is failure of an ancient o-ring a "malfunction" or a form of human error?

From a mechanic and tech point of view, you are correct. However a large group of divers have little or no idea what to do, or how to do, any maintenance. For them it is an equipment malfunction and the actual cause is beyond their understanding.

These divers are at the mercy of the people that train them and/or work at their LDS to inform them and work on their gear. The quality of care varies.



Bob

 

[Gareth J]

Overall failures are rare.

I guess the ones I remember are.

1. Regulator free flows, - normally cold water induced.
2. Extruding O-rings on A-clamps, not that I know many that dive A-clamps these days.
3. I once got grit under the diaphram on a second stage - result, inhaling a lot of water.
4. A borrowed twinset, rust causing the manifold to behave as if it was closed.
5. Exploded 2nd stage. Didn't happen to me.
6. HP seal degrading resulting in high interstage pressure, not good on a CCR, the overpressure valve protected everything. Unfortunately, it dumped a lot of gas.

Gareth

 

[Storker]

Regulator free flows, - normally cold water induced.

1st or 2nd stage?

 

[Gareth J]

1st or 2nd stage?

I don't think it is always easy to determine what where the initial failure started. Once you have a free flow, you normally end up with both first and second stage icing.

I have the impression that the majority of failures are probably second stage failures. Due to poor practice.

Often from breathing on the surface in very cold weather. Condensation from the exhaled breath causing icing in the second stage. Then you have the cascade effect of the second stage icing and free flowing, followed by the first stage icing and free flowing.

Gareth

 

[Storker]

I have the impression that the majority of failures are probably second stage failures. Due to poor practice.

That's my impression, too (albeit probably based on a smaller experience base than yours)

 

[Bert van den Berg]

Have had BCD butt dump valve cover come loose and had to tighten several times. Never actually came off because I caught it in time. Could be a problem if it comes completely off.

 

[Landlocked123]

The only serious equipment failure i have personally witnessed is a first stage pressure creep that led buddy to have a double free flow at both second stages. My BCD inflator button did stick a tad once. After I rinsed the BC and washed it the issue went away.

 

[Fibonacci]

Total loss-of-air equipment failures have thankfully been rare in my experience, most incidents were caused by insufficient or incorrect maintenance causing a major drop in performance but still passing air till the diver got to the surface.

However I did witness a dramatic event diving the President Coolidge years ago.
A USD first stage HP seat failed (apparently delaminated from the carrier) and dumped the entire contents of an 88 cu ft aluminium tank in a few minutes... diver was enveloped in ball of bubbles
'Luckily' it happened near the start of a deep dive just before he entered the wreck, so no deco obligations and the DM was right nearby.
The diver kept his cool... ascending slowly straight up buddy breathing, no heath issues afterwards.
Could have had a far more serious outcome if it occurred deep inside the wreck, at 45m with mandatory deco required!

 

[Storker]

However I did witness a dramatic event diving the President Coolidge years ago.
A USD first stage HP seat failed (apparently delaminated from the carrier) and dumped the entire contents of an 88 cu ft aluminium tank in a few minutes... diver was enveloped in ball of bubbles
'Luckily' it happened near the start of a deep dive just before he entered the wreck, so no deco obligations and the DM was right nearby.
The diver kept his cool... ascending slowly straight up buddy breathing, no heath issues afterwards.
Could have had a far more serious outcome if it occurred deep inside the wreck, at 45m with mandatory deco required!

Isn't this a pretty good illustration of why it isn't a very good idea to enter an overhead environment (physical or virtual) without a redundant gas supply?

 

[Fibonacci]

Isn't this a pretty good illustration of why it isn't a very good idea to enter an overhead environment (physical or virtual) without a redundant gas supply?

True, but all dives on that wreck were (and still are I believe) done on a single 88-90 cu ft tank (!)