What can make BCD malfunction?

[Bom]

I looked at my FB and found someone shared link about the death of divers in Bluehole. They said one of the causes is maybe the malfunction of BCD. So I have question. What can make BCD failure? I mean divers will know when they jump into water that their BCD is working or not. I can not imagine how BCD can fail under water without noticeable. Or at very high depth, it is totally different from 20-40m and it is too late for divers to go up?

Thanks,

 

[phoenix31tt]

I looked at my FB and found someone shared link about the death of divers in Bluehole. They said one of the causes is maybe the malfunction of BCD. So I have question. What can make BCD failure? I mean divers will know when they jump into water that their BCD is working or not. I can not imagine how BCD can fail under water without noticeable. Or at very high depth, it is totally different from 20-40m and it is too late for divers to go up?

Thanks,

you would assume so... some people don't test their inflator before the dive or don't do a leak test the night before the dive (or ever)...

anyways possible failure for a BC:

1. Inflator stuck on on
2. Bladder not holding air
3. Integrated weight buckles breaking and falling out

other "malfunctions" are most likely gear misconfiguration or user error... i can't see much else going wrong with a bc

 

[tbone1004]

1. correct, inflator freeflow is fairly common
2. bladder not holding air is rare that a seam would blow or a puncture happens that you don't notice, but that's why you do a positive pressure check as part of your gear setup
3. that's not a bcd failure per se

4. inflator elbow breaks
5. exhaust valve spring breaks causing leak

All except the weighting issue which isn't actually a BC failure can be verified during positive pressure checks. Inflate the BC until the dump valve goes, and let it sit for 5-10 mintes. If it's leaking you'll notice

 

[ams511]

Whenever there is a diving accident the speculation starts kicking into high gear. A BC is not a necessary piece of gear as divers were diving before their invention. You can have two problems with a BC, one if won't inflate and the diver sinks. Usually this is because the diver is overweighted and for some reason the BC is not inflating (probably because the air was not turned on properly). Unless a BC was ripped to shreds or the elbow breaks it should be able to hold some air. Second and probably more dangerous is a runaway inflator that sends the diver to the surface too fast and the diver gets bent.

 

[spectrum]

Outright BC failure is not common but the need for attention, especially with the inflater valve is common.

Potential failure modes:
Loss of buoyancy:
1) Jammed inflater exhaust valve (not common, at least for me)
2) Air cell seam failure/tear (not common)
3) Dump valve failure (not common unless one likes to tinker with valves when cleaning or is an animal with an inflater tug dump. This can often be mitigated by orienting the opening at the low point so the air cell can still contain a bubble of air.

Excessive Buoyancy:
1) Inflater stuck open, very common but it's usually gives warnings in the form of sluggish performance.
2) Integrated weights fall out
3) Dump valve pull cord breaks so you cannot vent on ascent, you almost always have multiple options.

Other: Tank band release/failure leading to air delivery system damage or panic

In a location such as the blue hole major neoprene is not likely so there is a good chance of swimming the rig up even with total air cell failure. Cold water, heavy neoprene and depth can make this less cut and dried. In such a case dropping a little lead can be a recovery at the risk of difficult ascent control. Drowned or DCS risk, the call is a no brainer for most.

It is also possible to have a lot of neoprene (that loses buoyancy at depth) and the requisite lead to sink it in the first place combined with a small air cell (travel BC/wing) such that the air cell cannot compensate for the neoprene crush. This would not be an actual BC failure but close enough for the media.

Inflater function and the air cells ability to be driven to firmness should be SOP before getting in the water unless you're doing a hot drop.

Pete

 

[drbill]

As pointed out, inflator hose not functioning properly; dump valve not working properly (stuck partially open and releasing air), bladder develops a hole (had that happen spontaneously at 200 fsw one dive). I've had every one of those happen since I first started wearing a BCD in 1989 (prior to that in the 60s and 70s we didn't use them). Since my diving in the early years was without a BCD, none of these need be a disastrous event if weighted properly. Several times I've simply disconnected my inflator hose and continued the dive. However, a new diver who may be overweighted and may not have had the experience of diving without a BCD could easily have trouble.

 

[timz]

Just a question to ask. How can BCD failure causes life??

1-Say if the inflator keep inflating ur BC, u just unplug it.

2-If it's not able to inflate, u can do it orally. Or even dive with empty BCD.

3-Say if the BCD puncture and emptied, diving is still possible if weight properly.

I was taught if we were weight properly, towards the end of dive we should have almost all air out from the BC.

Sorry... I am still new and I would like to know more. Certified as OW in April and only logged 21 dives.

 

[tbone1004]

1. correct
2. only possible with thin wetsuits at shallow depth and small ish cylinders
3. see above.

If you're diving with a 3mm wetsuit or less and a single AL80, LP72 etc you are OK to dive without a wing if you're weighted properly. Get into a 5mm, dive deeper than 60ft, have tanks bigger than that, etc. and your lungs can't compensate for that buoyancy shift.

 

[timz]

1. correct
2. only possible with thin wetsuits at shallow depth and small ish cylinders
3. see above.

If you're diving with a 3mm wetsuit or less and a single AL80, LP72 etc you are OK to dive without a wing if you're weighted properly. Get into a 5mm, dive deeper than 60ft, have tanks bigger than that, etc. and your lungs can't compensate for that buoyancy shift.

Thanks for the infomation. Really appreciate it.

But during the Open Water, we were taught to empty the BCD and kick to assend.

And say if we are wearing 5mm wetsuit, and properly weight, when we exhale we should still sink, no??

I know bigger tank will definitely create more positive buoyant at the end of dive, but that will only go up.

 

[mikeycanuk]

Once at my LDS, I saw the tech doing a service on the guts of a BCD inflator . It wasn't pretty and corroded pretty badly. It's something most of us never see, I get our BCD's serviced every 2 years.