Equipment failure and response: The free-flowing regulator

[TMHeimer]

The only one that's necessary is to continue breathing, surface normally with your buddy and share air if it becomes necessary.

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Highly unlikely, but you're at 80' and have buddy separation, then a free flow. Breathing from it beats a CESA. Or, you can be solo diving at 30 fsw (as I do a lot)--even then breathing from the free flow is probably the best/easiest option, especially if you don't start with full lungs.

 

[Kevrumbo]

You know, as part of Fundies, I had to demonstrate that I could reach and turn the valve on my single tank. It was very difficult to do, and required significant adjustment of my gear, as well as some changes in my exposure protection. I configure my single tank setup so that I CAN reach the valve, but there is no way on earth that I could feather the valve to allow myself to breathe while ascending. (I found that skill somewhat challenging in sidemount, where I could see and easily reach the valves!). I would not recommend any attempt to do that to a backmounted single tank diver. Sharing gas with a buddy, or making an ascent while breathing, either off the freeflowing regulator or your own backup reg, would definitely be preferable.

Even with a buddy there to donate the long hose primary reg, you just don't let your own free-flowing gas expire away uselessly with all its noise and bubbles --have your buddy shut down your cylinder valve and then ascend normally together sharing gas to your safety stop and surface. Worst case --if you lose your buddy to begin with-- Loosen that waist belt on your BP/W Lynne and reach back & pull that tank valve up to the back of your head. Feather/modulate the tank valve while doing a CESA to your safety stop & surface.

Difficult in single tank (not much easier in doubles tank manifold), but a vital skill and with LOTS OF PRACTICE --it can be done.

Actual incident (not a free-flowing 2nd stage regulator though):
Raja Ampat 2007, my DM/Guide has his tank valve O-ring extrude resulting in a major leak on initial descent to 12m depth; I donated my long hose, shut-down his tank valve, showed my SPG reading 190 bar (like you should always do during a S-drill), and we elected to continue the dive gas-sharing at 9m for 30min touring an absolutely gorgeous reef.

 

[flots am]

Highly unlikely, but you're at 80' and have buddy separation, then a free flow. Breathing from it beats a CESA. Or, you can be solo diving at 30 fsw (as I do a lot)--even then breathing from the free flow is probably the best/easiest option, especially if you don't start with full lungs.

You can always breathe from a freeflow until the air is gone. In fact there's no reason not to. It's perfectly good air regardless of whether your lungs were full or not.

There's no need to switch regulators or take it out of your mouth or do anything except surface with your buddy (or without your buddy if you managed to lose him).

 

[Kevrumbo]

You can always breathe from a freeflow until the air is gone. In fact there's no reason not to. It's perfectly good air regardless of whether your lungs were full or not.

There's no need to switch regulators or take it out of your mouth or do anything except surface with your buddy (or without your buddy if you managed to lose him).

Well in that instance ---hopefully you're at the surface already in good shape AND can orally inflate your BCD/Wing. But it gets even more confounding if you have a drysuit that's "shrink wrapped" tight upon surfacing. . .

Can you be in good enough condition on surfacing to ditch your weights, orally inflate you BCD/Wing but with no positive tank pressure remaining to effectively inflate your Drysuit --maintaining positive buoyancy-- all after just performing a near out-of-air CESA??

 

[TSandM]

If I had a freeflow, my first choice would be to go on my buddy's gas and turn my tank off, to get rid of the noise and the reduced visibility, and save the gas.

If I had no buddy at hand (2nd failure) I would go on my own backup reg, to get rid of the bubbles in my face, and ascend as quickly as I could safely do, with hopes of arriving at the surface before the tank was completely empty.

I would not attempt to feather a single tank unless I was desperately low on gas reserves to get to the surface. I honestly do not think I can competently do this, and I think trying to do it would just augment the stress of the situation.

 

[TMHeimer]

You can always breathe from a freeflow until the air is gone. In fact there's no reason not to. It's perfectly good air regardless of whether your lungs were full or not.

There's no need to switch regulators or take it out of your mouth or do anything except surface with your buddy (or without your buddy if you managed to lose him).

Agree. By lungs not full I just meant this makes a CESA less desirable as well.



Possible silly question-- If you have a free flow can you just let it dangle and breathe from your octo to ascend? I know that breathing from one's own octo if you are unable to retrieve a dislodged reg (reg retrieval skill) is not often mentioned in classes. But with a free flow, would the octo also free flow?

 

[Ricky B]

Possible silly question-- If you have a free flow can you just let it dangle and breathe from your octo to ascend? I know that breathing from one's own octo if you are unable to retrieve a dislodged reg (reg retrieval skill) is not often mentioned in classes. But with a free flow, would the octo also free flow?

Not a silly question at all. I believe it depends on the cause of the free flow.

If the free flow is the result of a problem with the first stage, then the octopus could free flow too.

If the free flow is the result of a problem with the second stage free that is flowing, then absent cold water causing a freeze-up, I don't think that the octopus would free flow.

 

[scagrotto]

It's just air.

It's compressed air that will expand. That's potentially very different than "just air".

In a properly designed modern regular, it's impossible to get more air than the exhaust valve can handle.

Does that mean anything other than the exhaust valve having low enough resistance that 140psig is enough to force the air through it?

Just press the purge button.

If you press the purge button air comes out the mouthpiece. Skip trying it in a pool. Do it in air and the venturi will result in flow continuing even after you release the purge button. That you can (usually) stop a freeflow by obstructing the mouthpiece, even partially, is a clear demonstration that the exhaust port is not capable of passing that volume of air with no increase in backpressure. That backpressure means that air is forced out the mouthpiece rather than being drawn out by a pressure reduction caused by inhaling. Freeflow means that your demand valve has been turned into a positive pressure ventilator, and the backpressure caused by the exhaust port will determine the pressure of the air being forced through the mouthpiece.

If nothing reduces the ability of that air to enter your lungs, then the overpressure in your lungs will be determined by the backpressure caused by the exhaust port. If the exhaust port causes less than 2 psi of backpressure then the lungs won't experience more than 2psi of overpressure. Can anyone authoritatively say that no freeflow scenario, including a high intermediate pressure, can result in more than 2psi of backpressure?

If not, then it's clearly important to make sure that the pressure isn't transmitted to the lungs. I can only see one way to be 100% positive that you're reducing the airflow enough, and given other options I'd prefer to have that 100% certainty. Ideally I'd have the option of my octo, my buddy's octo, an unobstructed path to the surface, and the ability to not have my lips tightly or fully wrapped around the mouthpiece of the freeflowing reg.

 

[Agility]

This person ... is most likely not using redundant first stages.

Exactly that was the intention of my post :blinking: to point out the necessity of additional preplanning.
If a diver plans to dive really cold water redundancy is a must IMHO.

 

[flots am]

. . .

You're working this really hard, and your theories, while fascinating, are not supported by reality.

Having actually had a number of cold water freeflows, assisted with many others, and having actually mashed the purge button on a number of regulators underwater, both in the pool and in OW, I can tell you that nothing remotely dangerous happens with the Atomic M1, Z1, Z2, SS-1, or the SCUBAPro Mk25/G250V, Air-2, or MK2/R195.

You can feel free to do whatever you want with your regulator. I'll leave mine in my mouth.