Equipment failure and response: The free-flowing regulator

[scagrotto]

your theories, while fascinating, are not supported by reality.

Perhaps, but you haven't supported your argument against them with anything other than some brief anecdotes. Nothing personal, but I don't find those anecdotes nearly as persuasive as actual data. In particular, the claim that "it's impossible to get more air than the exhaust valve can handle" is meaningless without actual data. A regulator that only allowed .1 CF/minute through the exhaust port wouldn't get more than it could "handle" either as it would, in combination with the mouthpiece, restrict the amount of air delivered. Perhaps all regs are engineered to ensure that it's impossible for mouthpiece to deliver a pressure that's 2psig, but I'm not going to assume that to be the case or accept a vague statement about what the exhaust port can handle.

I'd like to have actual data or an authoritative source. If you have something to offer, great. If you don't, then all you really know is that you're just unaware of any potential to cause injury, but that's not a guarantee that it doesn't exist.

 

[flots am]

I'd like to have actual data or an authoritative source.

I've had freeflows. I'm not dead or injured.

Over the past decade, hundreds of students have had freeflows during OW dives (it's cold here). None has been killed or injured.

I'm not sure how much more authoritative you're looking for, and frankly don't really care.

If you have something to offer, great. If you don't, then all you really know is that you're just unaware of any potential to cause injury, but that's not a guarantee that it doesn't exist.

That's correct. It's impossible to prove that something doesn't exist. Your regulator may very well kill you when it freeflows.

Mine has an exhaust port that's at least a hundred times the diameter of the orifice on the barrel, as well as decades of use, and has never done any of the things you're apparently concerned about.

 

[Diver0001]

The flow rate cannot exceed the exhaust valve capacity on a modern regulator. Stick your tongue in the mouthpiece if need be to modulate it. Go up, the surface is your safety zone.

N

Er..... yes it can. In the exceedingly unlikely event that the HP seat inside the 1st stage becomes dislodged the 1st stage can deliver about 1100 litres of air per minute to your 2nd stage. Basically, it's just blowing tank pressure straight into the 2nd stage.

I've only seen something like this happen once and only read about it online a few times in the time I've been active, but the pressure will literally blow the 2nd stage right out of your mouth.

This is the reason you're taught to breathe from the bubble stream. I do wonder if this protocol is still relevant in the 21st century because to be honest, I only recall hearing about one such failure in the last 15 years. It would appear that modern regs are engineered such that this failure mode may not be relevant to divers anymore.

What does happen a LOT are minor free flows, either bubbling or in cases of frozen regs, a fairly vigorous freeflow that conforms to your description of something similar to holding in the purge. These, can, in fact, be handled by keeping the reg in your mouth until you have an alternate available.

R..

---------- Post added April 23rd, 2014 at 01:22 PM ----------

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.

Lynne, it requires zero adjustment to your gear. It requires using two hands. Didn't they teach you that?

R..

 

[CamG]

Interesting thread my OW training consisted of Free Flow training.
We were trained in cold water so our instructor took plenty of time and training how to handle / become comfortable dealing with free flows.
As OW divers we learned if your reg starts to trickle "bubble" it is imperative to attempt to readjust it a little bit.
When it does this it can be an intro to a full blown free flow, no worries go to your buddy begin safe ascent on his octo and cut your tank off.
This was our OW SOP.

When we took AOW we were trained to use a pony bottle yes it is a bit much for Basic OW but our instructor was very methodical in his approach and made for certain everyone was comfortable / skills were up to par.
This being said if student were not comfortable they did not have to use ponys they could instead follow buddy OW protocol.

If we had a Deep Specialty it was a pony.
At our local training site we had two fatalities due to a free flows.
I was present the weekend after and witnessed many free flows personally and amongst training divers.
When water temps are 40º or below they re common place it takes very little to set them off.
THEY ARE NOT CRITICAL UNLESS YOU REACT POORLY!
If you are monitoring your gas, diving conservatively and train for them it is very well managed.

I give this word of caution just because you never dive cold water doesn't negate free flow training!
Sand, debris of any kind can cause free flows.
Gear repair / service issues can cause free flows.
Current, prop wash, etc.
Bumping alternate second stage / inflating BC / while taking a breath if your regs are tuned light could push it to flow or trickle.
The key is to properly service and train for them.
As previously stated they are not a big deal just manage them!

CamG

 

[fjpatrum]

RickyB, not to detract from this thread but there was a poster a few years back who posted several of these scenario based threads that I think you might be interested in reading. Might have been AWAP, but the search is only showing me posts back to 2012 now, so I can't find the specific links. I'll keep digging and see what I can find.

EDIT: Finally found some links--turns out these were from "Cave Diver":
http://www.scubaboard.com/forums/ne...what-if-physiological-issues.html#post5805602

http://www.scubaboard.com/forums/ne...514-what-if-what-do-when-things-go-wrong.html (This one's even a sticky in the New Divers forum)

http://www.scubaboard.com/forums/ne...g-diving/375573-what-if-equipment-issues.html

http://www.scubaboard.com/forums/ne...ering-diving/375571-what-if-lost-buddies.html

http://www.scubaboard.com/forums/ne...572-what-if-dive-planning-trust-me-dives.html

http://www.scubaboard.com/forums/ne...ng-diving/375575-what-if-computer-issues.html

http://www.scubaboard.com/forums/ne...ng/375576-what-if-miscellaneous-problems.html

 

[TSandM]

Two hands? Even reaching back and lifting the tank, I couldn't get to the valve where I initially had my tank placed. I had to raise it a LOT to get it to where the sequence didn't involve releasing the waist belt, lifting the tank, and then grabbing the valve -- a sequence I think I would have grave difficulty getting through if I jumped off a boat with my gas turned off . Raising the tank about five inches made the valve accessible, and then I had to redo my weighting to balance properly again.

 

[TONY CHANEY]

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??

If you were in good trim at the bottom then as the air expands during ascent you should have pleanty of buoyancy.

 

[Storker]

If a diver plans to dive really cold water redundancy is a must IMHO.

Just FTR, what's your definition of "really cold water"?

In my club, we don't make much of an issue out of diving in water down to 3-4 degrees C, and no-one is really concerned whether their buddy dives a standard single tank setup with a single 1st stage, or a twin setup with double 1st stages and an isolation manifold. We see free-flowing 2nd stage regs upon surfacing often enough, but so far I haven't seen anyone having a problem with free-flowing regs underwater. It's a rare enough phenomenon to be covered well enough by standard procedures like good buddy contact, air-sharing and the ability to shut down the tank valve of the offending gear.

Most of us are more concerned about freezing our a$$es (and fingers!) off after 30-40-50 minutes underwater...

 

[Diver0001]

Two hands? Even reaching back and lifting the tank, I couldn't get to the valve where I initially had my tank placed. I had to raise it a LOT to get it to where the sequence didn't involve releasing the waist belt, lifting the tank, and then grabbing the valve -- a sequence I think I would have grave difficulty getting through if I jumped off a boat with my gas turned off . Raising the tank about five inches made the valve accessible, and then I had to redo my weighting to balance properly again.

I'd have to see it. All of my OW students can access the valve by lifting the tank. I see this as basic equipment familiarity and they are taught to lift the tank and to familiarize themselves with how the 1st stage and valve feels on day 1 of the OW course. Knowing what I know about you, it's completely inconceivable to me that you could not.

R..

 

[Kevrumbo]

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??

If you were in good trim at the bottom then as the air expands during ascent you should have pleanty of buoyancy.

Not necessarily (with a drysuit and an empty tank):

http://www.scubaboard.com/forums/ac...ing-found-floating-kurnell-nsw-australia.html