BC Failure

[dumpsterDiver]

I was taught to always put air into my wing with the power inflator, then dump some, then orally inflate it, then dump some as part of a pre-dive check. This is a good test to see if anything sticks in the open or closed positions. Also, if diving a drysuit, put air into that and dump some, prior to diving.

Yes this is good practice and SHOULD be done. Probably had I done this before my dive, it is likely that I would have noticed a leak or something. I think the most likely problems this protocol will detect is the failure to connect the inflator and also an inflator that will continue to inflate after released.

Also, for normal BC's (NOT BP/w), donning the Bc when inflated is easier.

 

[padudle]

Pehaps I am a little off topic with this.

In my experience the corrugated hose of the power inflator is the most common serious point of failure in scuba. I have had two inflator hoses snap completely open in such a way that it would be impossible to put any air into the BC. In both cases this happened pre-dive but could easily have happened down below where the problem would be challenging to deal with.

I think it is time manufacturers reconsider the design of these hoses in order to maximize their reliability.

 

[bleeb]

In my experience the corrugated hose of the power inflator is the most common serious point of failure in scuba. I have had two inflator hoses snap completely open in such a way that it would be impossible to put any air into the BC. In both cases this happened pre-dive but could easily have happened down below where the problem would be challenging to deal with.

I think it is time manufacturers reconsider the design of these hoses in order to maximize their reliability.

Can you clarify exactly where you've had the problem? Is it down at the joint between the hose and the inflator mechanism, up at the shoulder joint, or the hose itself? Were these pull dumps? Some manufacturers do not build pull dumps because of the strain and what not, which might be one way of answering your suggestion, although it does sacrifice a bit of functionality.

 

[Akimbo]

Now you know how Mike Nelson felt during most of 20k dives(EDIT---without the SMB)------lol, ......My HERO, btw......

Our hero also didn’t have a BC to screw up or a wetsuit that crushed down to tissue paper at shallow depths (thus losing displacement). I have dropped 22 Lbs in 60’ with a ¼” Rubatex wetsuit that would have been more buoyant at depth and lived to write about it… right here actually.

The trip was a little fast compared to the normal 60’/minute ascent rate of the day, but it’s not like I breached like a Trident missile or put a hole in the boat. Fortunately that was before computers nagging me that my ascent rate was too fast!

dumpsterDiver would have been fine dropping his belt ala Mike Nelson, though it may have been a little more prudent to surface when he still had the weight of air in full tanks and minimal absorbed nitrogen. The problem with accidents is several small problems like this often compound into something serious.

 

[Akimbo]

… In my experience the corrugated hose of the power inflator is the most common serious point of failure in scuba…

It seems like we spend more time ruminating about what a serious problem BC failures are than it takes to teach people how to make it into a minor inconvenience and a learning opportunity.

 

[Charlie99]

It seems like we spend more time ruminating about what a serious problem BC failures are than it takes to teach people how to make it into a minor inconvenience and a learning opportunity.

Agreed, although there really isn't much to teach. It's easy for any diver to check out what would happen with a BC failure.

At the very beginning of your next dive, at least 60' and preferably deeper, drop to the bottom, empty all of the air out of your BCD. You have simulated a BC failure at the worst point of the dive ...... at the deepest part, and at the beginning with a full tank of air.

No see what it takes to lift off the bottom, whether you can swim around a bit, and how easy is it for you to ascend 10' or so. (The ascent will get easier as you go up and the wetsuit expands). If you can lift off the bottom, ascend 10' or so and swim around a bit, then you will be able to complete the ascent if desired.

It's an easy exercise, without any significant risks, and makes it so you know what to expect if you do have a BCD failure.

If you change to a thicker wetsuit, then you should repeat the exercise.

Simple. Just takes a couple minutes at the beginning of a dive. There's no excuse for not knowing what a BCD failure feels like and knowing whether you can swim yourself up.

 

[padudle]

Can you clarify exactly where you've had the problem? Is it down at the joint between the hose and the inflator mechanism, up at the shoulder joint, or the hose itself? Were these pull dumps? Some manufacturers do not build pull dumps because of the strain and what not, which might be one way of answering your suggestion, although it does sacrifice a bit of functionality.

Bleeb,

Yes, thanks for asking, the failure always occurs at the transition between the thick rigid material and the thinner rubber that is intended to stretch.

In one case it occured where the rubber hose attached to the hard plastic shoulder dump fitting.

In the other case it split more near the middle right along the transition between the thick rubber and thin rubber sections that form the corrugation.

Our BC's have shoulder dumps but we never use them. We use the hip dump or lift the power inflator. We never pull on the inflator.

In my opinion, these corrugated hoses are lacking what I call strain relief. Any time you design something that goes from a hard section to a flexible section it is necessary to put a transition called strain relief. Look at the various power and data cables scattered around your desk. Where they go from the hard plastic plug to the flexible cable there is a section of semi-flexible rubber. That semi-flexible strain relief reduces the chances that the cable will fail right at the transition from the plug.

In the case of a power inflator hose the strain relief can be built right into the design of the hose. The sections close to the hose clamps should be thicker, stronger and less flexible and then gradually transition to the fully flexible corrugation.

 

[Freezerbrn]

Great info. I have to say that I read this post just before an open ocean wreck dive dive to 120fsw. I thought about what I read here regarding the use of an SMB to ascend if I had a wing failure. The more options to readily turn too in the event of equipment failure helps keep panic at bay. My buddy was there too but it's nice to know your options. And boy did I check the heck out of my inflation hose connections and pull dump.

Thanks

 

[dumpsterDiver]

Great info. I have to say that I read this post just before an open ocean wreck dive dive to 120fsw. I thought about what I read here regarding the use of an SMB to ascend if I had a wing failure. The more options to readily turn too in the event of equipment failure helps keep panic at bay. My buddy was there too but it's nice to know your options. And boy did I check the heck out of my inflation hose connections and pull dump.

Thanks

People can learn a lot from my mistakes. Wonder if I learn anything??

 

[fjpatrum]

Bleeb,

Yes, thanks for asking, the failure always occurs at the transition between the thick rigid material and the thinner rubber that is intended to stretch.

In one case it occured where the rubber hose attached to the hard plastic shoulder dump fitting.

In the other case it split more near the middle right along the transition between the thick rubber and thin rubber sections that form the corrugation.

Our BC's have shoulder dumps but we never use them. We use the hip dump or lift the power inflator. We never pull on the inflator.

In my opinion, these corrugated hoses are lacking what I call strain relief. Any time you design something that goes from a hard section to a flexible section it is necessary to put a transition called strain relief. Look at the various power and data cables scattered around your desk. Where they go from the hard plastic plug to the flexible cable there is a section of semi-flexible rubber. That semi-flexible strain relief reduces the chances that the cable will fail right at the transition from the plug.

In the case of a power inflator hose the strain relief can be built right into the design of the hose. The sections close to the hose clamps should be thicker, stronger and less flexible and then gradually transition to the fully flexible corrugation.

I don't mean to be rude, but the entire corrugated section of the hose IS the strain relief. I don't know why you've had multiple failures, but that isn't normal in the hoses I've seen buying used gear. (So far I've bought half a dozen or so old BCs.) All of them have equally thick sections of non-corrugated hose where they are intended to attach to inflators and elbows. I'd dare say if you're having failures then you may have gotten a couple of lemons or someone is cinching the tie wraps too tightly.