Prevent regs from free-flowing when you surface-swim?

Please register or login

Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

Benefits of registering include

  • Ability to post and comment on topics and discussions.
  • A Free photo gallery to share your dive photos with the world.
  • You can make this box go away

Joining is quick and easy. Log in or Register now!

alex_can_dive

Contributor
Messages
129
Reaction score
52
Location
Massachusetts
# of dives
25 - 49
Hey there~!
I've got noob question. I notice when I surface swim (using my snorkel to conserve air), my reg, which is out of my mouth, sometimes flies around and if the mouth piece faces upward, it'd start to free-flow.
I've tried to to mitigate it by holding it in my hand and swim with just one hand like an idiot :(.

Is there a better way to prevent this?
 
Hey there~!
I've got noob question. I notice when I surface swim (using my snorkel to conserve air), my reg, which is out of my mouth, sometimes flies around and if the mouth piece faces upward, it'd start to free-flow.
I've tried to to mitigate it by holding it in my hand and swim with just one hand like an idiot :(.

Is there a better way to prevent this?
Clip it off to a d ring. Waist d ring will probably be better than shoulder d ring to ensure it is submerged. Also if your reg has a pre dive adjustment valve, use it.
 
tbh, with fins on, you shouldn't really need to swim with your hands at any point, even on the surface!

You can swim on your back for some distance (as long as there is nothing to crash into!) , arms crossed and this keeps the front of you a bit drier, and put the reg looped over onto your front in your arms

Always make sure the reg is removed and carefully submerged, so both side of the diaphram see water pressure, any trapped air in the main body can cause enough deltaP to crack the reg.

When you remove it you can also loop the hose (depending on length) around or under something (like your weight belt, neck), or bcd pocket or strap) to keep the reg tight in to your body.

Finally, do an easy cracking check to be sure your reg isn't set too lightly (make sure there is no water in the main body, connect and pressurise, then lower diaphram first , mouth pieve upwards, into water, and you should be able to hear the reg cracking and juuuust starting to flow air at between 1 to 1.5" of water depth but no less. Usually, the reg should crack as the water line just about hits the bottom of the rubber mouth piece
 
> You can swim on your back for some distance (as long as there is nothing to crash into!) , arms crossed and this keeps the front of you a bit drier, and put the reg looped over onto your front in > your arms

I can't control where I'm going if I'm on my back - yet to work on that :)


> Always make sure the reg is removed and carefully submerged, so both side of the diaphram see water pressure, any trapped air in the main body can cause enough deltaP to crack the reg.

Can you elaborate on the "carefully submerged"? What is the right way to submerge it?

Thanks!!!
 
A second stage regulator works on differential pressure between your lungs and the ambient water surrounding you.

When it's in your mouth, the inside of the reg is at the same pressure as your lungs, and the outside of the reg at ambient. As you breath in you create a small difference in pressure between your lungs and airways and the ambient pressure and this "draws in" the soft flexible diaphram on the front of the reg (the side that is opposite the mouth piece). As that diaphram pulls inwards, it pushes down on a lever, and that starts to open a valve that lets high pressure air (at around 10 bar above ambient as controlled by the 1st stage regulator) flow into the volume formed by the reg, your airways and your lungs. When your lungs are as full as you need, you stop breathing in, the air pressure in your airway reaches just slightly above that of the ambient water pressure, and the diaphram moves forwards, letting the air demand valve close, and so stopping the flow of air.

In reality, it's not an on/off type arrangement, but a proportional one. The harder and faster you breath in, the more the diaphram moves and the more it opens the demand valve and the quicker air flows into your lungs.

In order to feel "easy to breath" the cracking pressure, the differential pressure at which the demand valve starts to open cannot be to large, or it feels like you are sucking in but not getting any air.

But in order not to freeflow, the cracking pressure shouldn't also be too low, otherwise the diaphram can move too easily and push on the demand valve, and send air into the reg when it's not wanted.

This is most often an issue when the reg is out of your mouth. Here, the roughly 1" to 1.5" of water differential pressure it takes to push the diaphram and open the demand valve really isn't very large, so it can be easy to have the regulator "free flow" when it's out of your mouth, even when it is set perfectly.

If when you are on the surface and you put the reg down from the air, and into the water front face first, ie diaphram down, mouth piece upwards, a small bubble or air can be caught under the diaphram, and as the reg is pushed more than 1.5" below the surface, that opens the Demand valve and air flows out. Because of an effect called the "venturi effect" once the air has started to flow out, it cam keep going and be a little harder to stop, so a freeflowing reg that has been submerged in this way can stay feeflowing, wasting your air and making a loud bubbling mess.


So, when you put the reg into the water, lower it in sideways, ie with the hose facing up, the diaphram and mouth piece level on each side, so that as it goes under the water, the water pressure can easily flow into the open mouth piece and fill up up the insides of the regulator at exactly the same time as it fills up the diaphram side. This means no differential pressure can happen, and the reg doesn't freeflow.
Once the reg is below the water, and the inside and diaphram side are full of water, ie no air, then there is also no differential pressure so no freeflow. However, if the purge button is pressed or knocked, that can have the effect of setting off a free flow as it pushes the water that is currently in the reg out, and once again a differential pressure occurs!



This also makes it real easy to check the cracking pressure is set to a sensible level. Simply make sure the air is on, and deliberately lower the ref carefully into the water, level as possible, diaphram side down, mouth piece straight up, and when you reach a depth of about 1 to 1.5" of water, normally just as the water gets to the mouth piece, you'll hear the reg crack and start to flow!. If it cracks before this point the cracking pressure is too low, and if you can get the whole reg submerged before it flows the cracking pressure is too high

Hope that explains things :)
 
second-stage.jpg


A picture is worth (at least) a thousand words..... ;-)
 
Regs that aren’t in your mouth should be de-tuned.
That's going to be tough with my classic Mares seconds.

I find that submerging them any way other than face down does the trick and is way more comfortable than swimming around with an inline adjustment tool screwed to my reg.
 
swimming around with an inline adjustment tool screwed to my reg.
Too bad your reg doesn't have an adjustment knob.....
 
https://www.shearwater.com/products/swift/

Back
Top Bottom