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.
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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?)