Regulator Free Flow

[Buliwyf]

Don't you still have about 30 seconds of air to breath from your good regulator during a free flow as you fight the free flow on the way up? Isn't that enough to get to the surface?

If I answered "no" to either of those, I'd carry a pony or doubles.

Panic is an entirely more serious problem.

 

[dberry]

The venturi effect does not cause the valve to open bt it does enhance the flow rate once the valve is opened. The water pressure on the front cover in high current situations may open the valve. Or the reg could have been bumped causing the valve to open.

That makes sense, and he might very well have bumped it, too.

I should be able to figure this out myself, but pardon an ignorant / lazy question: when a reg free-flows at the surface you can often stop it by just turning it mouthpiece-down. How come?

 

[redacted]

That makes sense, and he might very well have bumped it, too.

I should be able to figure this out myself, but pardon an ignorant / lazy question: when a reg free-flows at the surface you can often stop it by just turning it mouthpiece-down. How come?

Closing off the mouthpiece will bstop the venturi effect. placing the mouthpiece down in the water has a similat effect as the extra depth of water increases the flow resistance. But if the venturi effect is too strong, it may keep flowing.

 

[Bob DBF]

The venturi effect does not cause the valve to open bt it does enhance the flow rate once the valve is opened.

That would be the reg design and happen after the diver or some other mechanism lowered the pressure enough to cause the reg valve to operate.

Although a venturi or bernuelli effect could cause a freeflow, if the right conditions exist, more likely it would be caused by turbulent flow around the diver(s) which cause small areas of low and high pressures in the swirl of the water. A low pressure area by the mouth of a reg could be enough to start a freeflow. None of my purge buttons are/were that easy to operate that a tap would make them work, but I have no new expensive regs.


Bob

 

[Storker]

always validate your intermediate pressure every 10 dives or so or every 20 dives. I validate my Intermediate Pressure before every use, especially if the regulator I've chosen for a particular dive or trip hadn't been in use for a while..

That seems a little... overblown to me. I have my regs serviced every second year or fifty dives, whatever comes first. Except for the occasional over-light tuning during service, I've never had an issue with them. But then I swear to proven cold-water reg designs

 

[redacted]

That seems a little... overblown to me. I have my regs serviced every second year or fifty dives, whatever comes first. Except for the occasional over-light tuning during service, I've never had an issue with them. But then I swear to proven cold-water reg designs

Such excessively frequent servce is likely to prevent IP problems and make your tech very happy. Those regs are likely to be just as reliable on a 4 year or 100 dive service interval. But the importance of an occasional IP check to head off incipient problems would increase.

 

[Subcooled]

I'm a new diver, and have done a few dives since being certified, but I worry about free flows. I suppose the reason why I worry is because I haven't experienced it during a deeper dive. What techniques have you found work best when encountering this?

More air is delivered than you can breathe, so you are not about to suffocate really. Lots of bubbles and noise can be scary though

Typically, you have breathing gas for a moment (and two and three moments), so you could EASILY surface from 20m/60ft. 10 m/min is the recommended ascent speed, but in the past fit people have ascended twice as fast. And yes, you can hold your breath (and exhale on ascent of course) up to two minutes if you must. Plus there's violent air flow for quite some time.

All that I am saying is that a free flow at -20m is not a major crisis. Inform your dive buddy and ascend to the surface. You can always borrow your buddys other regulator but why not breathe the leaking air first instead?

If the air flow cools your teeth and causes pain (I have experienced that) and blurries your reasoning ("it hurts - I must get out"), then just remove the regulator from your mouth and only insert it for breathing.

REMEMBER TO EXHALE EVEN IN THIS SITUATION
(remember that expanding compressed air can destroy your lungs and that this is actually the relevant risk here)

Those of us that can feather a valve, will find free flows a mere annoyance. Free flows are quite boring really if one has double tanks and can reach the valves. Two small tanks is soooo much better than one big.

----------
There are two types of free flows. Those caused by the second stage (exhaled air freezes and causes ice crystals that stop the 2nd stage from closing - inevitable in arctic waters - wait for it to come) and those caused by first stage freezing (did you really put DRY air in the tanks?)

 

[Subcooled]

If it's the BCD inflator that free flows instead, then breathing will be a lesser concern as you turn into a human missile and head for the surface very fast

I once surfaced from -20m involuntarily maybe in 30 seconds enclosed in a huge cloud of bubbles. I only focused on exhaling on the way up and that is why I did not destroy my lungs and die. Oh yes, there was air. Plenty of it.

You always have the option to disconnect the hose - although it requires practice or you will forget it as I did...