Most common open-circuit equipment malfunctions leading to problems?

[scubadada]

Narrowly escapes imminent death due to catastrophic equipment failure at nearly 200 feet, (switches to pony, deploys smb, AND doesn't ditch his speargun) surfaces and... nonchalantly frees fouled prop...

Sometimes I miss dD

 

[JasmineNeedsGills]

I'm wondering what the most common equipment malfunctions are that can lead to serious problems. I can see the following being possible, but not sure how common they are.

- O-ring failure between the tank and first stage
- Stuck inflator mechanism on the BCD and/or drysuit

First stages are very reliable, right? Is it very rare for a first stage to suddenly stop delivering air or to leak air catastrophically?

When I was doing pool training, the other trainee with me had the inflator stick open on her BCD, and she went up like a cork. Thankfully it was only in a 3 metre deep pool so no harm done, but had it been at depth it could have become a nasty situation. Equipment failures aren't common, but they do happen. And when they do happen - even if they are salvageable by themselves - it can lead to panic and a classic incident pit scenario develops.

Same with a first stage issue, it might not be common, but if it does happen it makes the octo kind of pointless. When I start diving again, I'm seriously considering either a pony or a Y valve to have 1st stage and O-ring redundancy. Better safe than sorry.

 

[BlueTrin]

Here's a Zeagle first stage total diaphragm failure (8:42) on a solo spearfishing dive at 180 feet (55m)
At least he kept cool, had a 13 cu ft pony and deployed a SMB at depth (using his pony to inflate it!)

I need to watch this properly when I get home. This guy seems to have nerves of steel

 

[ajduplessis]

Sometimes I miss dD

Got hit by Chinese censorship policy

 

[SvR]

Same with a first stage issue, it might not be common, but if it does happen it makes the octo kind of pointless. When I start diving again, I'm seriously considering either a pony or a Y valve to have 1st stage and O-ring redundancy. Better safe than sorry.

Here in Switzerland, we use tanks with two valves and two 1st stages. Octo and primary go to separate stages. Same with inflator and drysuit.
I also have SPG and pressure sensor from the computer to separate stages.

I had two O-Ring failures so far. One (rented) broke immediately on land upon opening the valve.
Another one was leaking very small bubbles on occasion which I found out in the bath tub were I checked my gear after reconfiguring a 1st stage for vacation.

Btw, how long do they last in storage? Eventually, I should throw away and rebuy my spares.

 

[clownfishsydney]

My experience over more than 4,300 dives follows.

• Most o-ring failures happen when the tank is first turned on. I have only ever seen one such failure underwater and this was because the o-rings were really soft. On that trip, we had probably 20 o-ring failures over the week on the boat.
• I have had one first stage failure with free flow at 45 metres. Used this air till it ran out and then switched to second tank. I have never seen another such failure underwater.
• First stages falling apart underwater - seen this twice, design faults permitting parts to become loose and fall off, leading to failure of reg. Not dangerous problem as switching to octopus solves problem.
• I have had numerous second stage problems, with small free flows. Most related to sand in the reg from beach entries and were minor or able to be rectified underwater. I would say that this is the most common problem I have seen.
• Inflators self-inflating, I had one BCD that did this all the time unless I pulled apart and cleaned it every 10 dives. I have seen this happen to many people too, but for an experienced diver it presents no problem as you just disconnect it.
• Sticking tank valves, I have seen this a couple of times and leads to inadequate air supply at depth or towards the end of the dive.
• Drysuit floods, have seen a couple of times where they totally fill with water, easily handled by experienced diver but for a newer drysuit user or newer diver, could cause problems.
• Mask straps breaking underwater (or mask breaking), more common and can cause problems for insecure divers.

That's about all I can think of, gear properly looked after and used regularly is very reliable.

 

[The Chairman]

The most common failure is the nut loose behind the mask.