Freeflow regulator question

[PaulG]

I have been reading the BSAC diving incidents for 2004 and there seem to be a good percentage of freeflow regulator problems which then end up in either a more rapid ascent than prudent or arriving on the surface with no air in main tank.

I have a question which I am hoping someone may be able to answer before I have to try it in a real life situation.

If I encounter a free flow primary reg and cannot cure it by purging etc, would it work to switch to the octo and then fold the primary hose in half to stop (or at least dramatically reduce the airflow from the primary reg) to allow a more controlled ascent time.

When I was in the motor trade, I did this all the time with high pressure airlines when switching from one air tool to another and same principle applies with a hosepipe so I assume it would work with a reg hose.

Am I wrong and it does not work or is it just that most people would not think to stop the flow with this method, especially with the added stress of being 20m underwater?

 

[FatCat]

If I encounter a free flow primary reg and cannot cure it by purging etc, would it work to switch to the octo and then fold the primary hose in half to stop (or at least dramatically reduce the airflow from the primary reg) to allow a more controlled ascent time.

It does work. It even works quite well, provided your first stage isn't frozen. So even though it's a useful procedure for stopping second stage freeflows, it's best to dive with two first stages.

BTW, Apeks sells a gadget - I forget what it's called - you screw in between your LP hose and your second stage. In case of a freeflow, you just pull back on this gizmo (something like disconnecting an LP connector) and it shuts off the airflow to your second stage. A few minutes later you can re-open the airflow by repeating the operation.

Also, second stage freeflows are mostly caused by all-plastic designs, so look for a second stage with either a metal finish or a metal heat exchanger.

 

[RiverRat]

I have been reading the BSAC diving incidents for 2004 and there seem to be a good percentage of freeflow regulator problems which then end up in either a more rapid ascent than prudent or arriving on the surface with no air in main tank.

I have a question which I am hoping someone may be able to answer before I have to try it in a real life situation.

If I encounter a free flow primary reg and cannot cure it by purging etc, would it work to switch to the octo and then fold the primary hose in half to stop (or at least dramatically reduce the airflow from the primary reg) to allow a more controlled ascent time.

When I was in the motor trade, I did this all the time with high pressure airlines when switching from one air tool to another and same principle applies with a hosepipe so I assume it would work with a reg hose.

Am I wrong and it does not work or is it just that most people would not think to stop the flow with this method, especially with the added stress of being 20m underwater?

Interesting concept. I suppose it would depend on the internal structure of the hose, how it's reinforced. Or could one actually burst the hose by bending it sharply causing even more air to flow? If one were relatively shallow I would not bother but it might be worth investigating for use on deep dives.

 

[diverbrian]

It's an idea. As someone who dives with his regs set too sensitive some of the time, I normally dive doubles (preferred) or a large tank with an H-Valve. Either way, I can have a free flow isolated in less than a minute, have a breathing reg in my mouth and restore air to my reg that acted up in the first place shortly thereafter. I practice this for the reason that I normally dive cold water. Forty degrees is not uncommon to dive in where I live and many times it is colder than that in the water.


I have even done it in a recreational set-up. By the time that I am done exhaling, I have my reg unfrozen and ready for action again. Just make sure that your buddy is there to share air with in case that won't happen for you. Some advanced courses will make you breathe out of the hose and isolate, breathe out of the hose and isolate, etc. That is for major regulator malfunctions in an overhead environment and has saved some lives when used for real. But, PLEASE don't try this without training. As you can imagine, it can leave a diver without breathing gas if screwed up and that is not a good thing.

 

[emtdan]

http://www.aqualung.com/products/free_flow_control.html


It's called a "Free-Flow Control Device", a very original name.

I dont quite understand how it works, though...

 

[MikeFerrara]

The first step is to get comfortabal breathing a free flow and controling buoyancy and position. If you can't do this you'll have trouble reacting regardless of which action you choose.

The valves made by Zeagle as well as kinking the hose are poor choices in my opinion because if it's the first stage that's frozen (or HP seat failed for whatever reason) the air is still going to come out someplace. That means that if there's another second stage attached to that first stage that it will free flow. If there isn't another 2nd stage as in when using an h-valve or doubles then something still has to give possibly a burst hose because if the first stage is wide open you'll be applying tank pressure (3000 psi?) to the intermediate side and hoses.

Also if one reg is free flowing full out and you switch to another second stage that's coming off the same first stage it may not breath real well.

On a recreational no-stop dive where proper gas management is employed you should have no trouble either making your ascent breathing the free flow or switching to a buddys alternate. Obviously a step up from that would be redundant regs like an h-valve or doubles because you can isolate the failure and switch to your own backup.

In my experience the reason so many get in trouble with this is that they can't breath a free flow midwater and control their position. They either panic and blow or all the bubbles in the face and the distraction just sends them to the surface without them even realizing it.

The fact that some agencies don't teach this at all and others allow it taught kneeling on a platform is obsurd and sets you up for trouble unless you realize what you really need to be able to do and go teach it to yourself.

 

[pilot fish]

How can one practice this to achieve some level of experience with a free flow reg? Would you hit purge and hold it to simulate free flow to practice? This was only covered lightly in my OW cert, as I recall

 

[RiverRat]

How can one practice this to achieve some level of experience with a free flow reg? Would you hit purge and hold it to simulate free flow to practice? This was only covered lightly in my OW cert, as I recall

Yes, in my OW we sipped off the reg in the pool while holding the purge. Something to practice in shallow water with a buddy.

 

[knotical]

If I encounter a free flow primary reg and cannot cure it by purging etc, would it work to switch to the octo and then fold the primary hose in half to stop (or at least dramatically reduce the airflow from the primary reg) to allow a more controlled ascent time.

Another method that stops some freeflows that you might or might not have had in mind when you said "by purging etc", is: after switching to your alternate, put your thumb in the offending mouthpiece air hole, thereby producing backpressure.

As for kinking the hose: it sure used to work and I think would still work even with more modern hoses. But, if I had to do this, I'd surely replace the hose and have the first stage checked/serviced before diving that reg set again.

 

[Rick Inman]

http://www.aqualung.com/products/free_flow_control.html


It's called a "Free-Flow Control Device", a very original name.

I dont quite understand how it works, though...

My first though about ths thing was, You've got to be kidding! First stages are designed to fail open for a reason. Adding a device that shuts off the flow of air seems a dubious answerer at best.
Not for me, thanks. The real answer is... well, see Mike's quote below.

The first step is to get comfortabal breathing a free flow and controling buoyancy and position. If you can't do this you'll have trouble reacting regardless of which action you choose.

The valves made by Zeagle as well as kinking the hose are poor choices in my opinion because if it's the first stage that's frozen (or HP seat failed for whatever reason) the air is still going to come out someplace. That means that if there's another second stage attached to that first stage that it will free flow. If there isn't another 2nd stage as in when using an h-valve or doubles then something still has to give possibly a burst hose because if the first stage is wide open you'll be applying tank pressure (3000 psi?) to the intermediate side and hoses.

Also if one reg is free flowing full out and you switch to another second stage that's coming off the same first stage it may not breath real well.

On a recreational no-stop dive where proper gas management is employed you should have no trouble either making your ascent breathing the free flow or switching to a buddys alternate. Obviously a step up from that would be redundant regs like an h-valve or doubles because you can isolate the failure and switch to your own backup.

In my experience the reason so many get in trouble with this is that they can't breath a free flow midwater and control their position. They either panic and blow or all the bubbles in the face and the distraction just sends them to the surface without them even realizing it.

The fact that some agencies don't teach this at all and others allow it taught kneeling on a platform is obsurd and sets you up for trouble unless you realize what you really need to be able to do and go teach it to yourself.

How can one practice this to achieve some level of experience with a free flow reg? Would you hit purge and hold it to simulate free flow to practice? This was only covered lightly in my OW cert, as I recall

Last year we had free-flow issues every week. My main buddy and I have both replaced our cheep regs, so (so far) we aren't having any free-flow-fun. It became routine to share air, shut off the free-lowing tank, wait a minute for it to defrost, turn it back on and continue the dive. I once made an ascent from 90 feet on a free-flowing reg, nice and slow, had my buddy turn me off at 15 feet for the safety stop and I did the safety stop on my pony. No problem.
Yeah, you can practice in the pool. But most of the time, we would just share air for a bit and let the first stage defrost. Sharing air is a BASIC skill and should be no big deal.