Free flow from reg or over pressure valve on bcd when jump into water?

the past few dives I have had, whether giant stride entry or backwards roll, my reg free flows for a bit, until i face the reg down to stop it. The rest of the dive is fine. Also if my bcd is filled, could the force of the entry cause it to deflate some of the air via the OPV? Could explain the loud noise when i enter the water.
One time when i jumped in, my reg free flowed and managed to blow my mask off my face, and i ended up losing it.

Just wondering if anyone has experienced any of this before.

A common problem with divers as they enter the water is having the mouthpiece facing up. There is a pressure differential in the inverted 2nd stage which causes the lever to open and air flows directly up. This is not a fault of the reg- just something to avoid.

Sometimes the reg is tuned very 'loose' which makes it difficult to stop the free flow once started. A finger pressed smartly against the mouthpiece is sometimes all it takes, but I've had to turn air off in order to stop the freeflow before.

Again, if yours stops freeflowing if you turn the mouthpiece down, that's good and nothing to worry about.


A fully inflated BCD will burp excess air on intial impact with the water- try to avoid filling the BCD as full as possible. You shouldn't need it completely full in order to come to the surface after entry- especially if you are correctly weighted. Cold water diving requires more air in the BCD to combat the extra weights worn, but again, you shouldn't need it fully full to regain the surface after entry.

You're talking about 2 separate issues...

Issue #1: Reg freeflow during water entry

With which second stage are you having freeflow issues? The primary (which is in your mouth during water entry) or the octo?

If it's the primary that's freeflowing, you can opt to put your hand over the 2nd stage during a backroll entry to prevent water from forcefully hitting the purge button.
Typically, the octo is adjusted with a slightly higher cracking pressure and the Venturi lever is set to predive/- to prevent a forceful, sustained freeflow. Even with these adjustments, the octo can freeflow a little during water entry. It's usually not a big deal.

FWIW, a well-adjusted second stage reg will initiate flow if it is submerged in water with the mouthpiece pointing up.

Issue #2: BCD OPV(s) activating during water entry

Yes, it's certainly possible that with a fully inflated BCD, one or more OPVs will activate (open up) during water entry due to the force of hitting the water. If you don't like the sound, I suppose you could inflate the BCD less.

On a side note, make sure that you are properly weighted by doing an in-water weight check. I've known some beginner divers who were substantially overweighted, so they had to keep an excessive amount of air in their BCDs.

Agree with everything Bubbletrubble said.
Don't forget to hug your hoses, that way your mouthpiece won't flop in front of your mask and blow it off.

supergaijin:

Cold water diving requires more air in the BCD to combat the extra weights worn, but again, you shouldn't need it fully full to regain the surface after entry.

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This shouldn't be the case on entry if you're properly weighted. Your wetsuit or undergarments gives you bouyancy as well.
I use a few puffs of air on my inflator whether in a 3mm or a 7mm farmer john. Always have bobbed back to the surface, no problem.

g1138:

Agree with everything Bubbletrubble said.
This shouldn't be the case on entry if you're properly weighted. Your wetsuit or undergarments gives you bouyancy as well.
I use a few puffs of air on my inflator whether in a 3mm or a 7mm farmer john. Always have bobbed back to the surface, no problem.

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Hitting icy water tends to make you inhale a bit too.

But true- the extra weights worn are to get you down with an extremely buoyant exposure suit.

Finally- with a bit of practice, you'll learn to orientate yourself pretty quickly as you hit the water. A couple of fin kicks and you're up straight away.

I assume that you are a new diver with new equipment. So take the reg into your LDS and have them look at it as the cracking pressure may need adjustment. If you purchased online you have to decide if this is a problem, or new diver syndrome. If you feel it needs adjusting then send it in to have this done. You can also take it to a local shop, but they may charge $50 for the pleasure of turning a screw 1/4 turn! ScubaToys charges $20 plus parts to service a second stage just to give you an idea.

I think servicing a second stage requires skills you can gain in an hour, the problem is where do you learn this stuff? I've taken them apart and there is not much there.... this may be of use Dive Industry Technician Service Course, scuba regulators spare parts, compressors, scuba tanks, regulator service manuals

So what exactly is a free flow and what causes it? (Mine will sometimes do it when taking it out of my mouth underwater). What's going on when it happens and why do the solutions work?

I've had free flows, never while diving at depth, but only on entry. Never had the ones where you cant stop it either. In the future I will inflate bc less and try hold onto hoses and see what happens.

diverzach:

So what exactly is a free flow and what causes it? (Mine will sometimes do it when taking it out of my mouth underwater). What's going on when it happens and why do the solutions work?

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To explain this I have to explain the basic workings of a second stage. You have a rubber hard seat that's seated along the opening of your hose to your second stage. As you breathe you lower the pressure inside the second stage. This flexes your purge diaphragm which pushes down a lever; exactly the same way when you press your purge button. This lever lifts the hard seat off the hose opening and allows air to flow.

When you hit the water on entry you may hit your purge button causing a free flow. When the hard seat gets too worn you may also get a free flow. A free flow occurs and doesn't stop because of the Venturi Effect. It's the same effect that occurs when you siphon water from a fish tank or gas from a gas tank.
Basically when you get a fluid (gas or liquids) running through a tube from one reservoir to another, it will not stop running until you put an external force to stop that flow or until your donor reservoir runs out.

So in the case of a free flow, it will not stop until your tank runs out or until you put an external pressure to stop the flow. This can be water pressure by turning your reg so the mouthpiece is down, or by air pressure by covering your mouthpiece, allowing air to fill the second stage w/o escaping.

Either method allows air to fill the second stage which flexes the diaphragm out, releasing your lever which seats the hardseat back on the hose opening. If your hard seat is worn then you'll still have a freeflow.