regulator free flow

OceanicRocks · Oct 31, 2007

Hi guys/gals,
Got into the pool for the second time with my new FDx10 delta 4 reg. it has a pre dive and the adjustment knob on the side. so I hooked up the gear and purged the valve on the second stage and imbarassing free flow at the pool (very loud). the instructor came over and sorta looked at me like... does this guy even have certs? he said just place your thumb over the reg to prevent free flow. It worked. The only reason for the confusion is that I was busy turning the knob on the side of the reg. as I was told that would stop the free flow. Come to think of it now I dont think that the pre-dive switch was in the right position. :shakehead:

I felt like an :mooner:... I was a bit like a kid in the candy store that could not wait to get his mouth on the candy. Please confirm that its me and not the reg. Yup I'm asking for punishment, but only if I deserve it. If you think that its the reg. I'd rather have it checked out... Oh BTW it never free flowed during the dive. :shakehead:

texdiveguy · Oct 31, 2007

This has - does - and will happen to all us divers!!!! Your reg. I bet is in fine shape...so probably know worries there. Next time it FF just turn over the second stage to point the mouth piece down and or place a finger or two over the mouth piece opening as your instructor did...this will stop that lions roar!!!

redacted · Oct 31, 2007

It sounds like your reg is well tuned and behaving as it should. The adjustment knobs will prevent or reduce the severity of a freeflow, but are not normally used to stop it once it gets started. The thumb ove the mouthpiece blocks the airflow and stops the "siphon" effect that sustains a freeflow. With the reg in your mouth, the problem will also be prevented.

DA Aquamaster · Oct 31, 2007

There is a difference between stopping a slight freeflow caused by the regulator being adjusted slightly too light (which may occur with the knob all the way out on the surface or even with it in a bit in a face down position in the water where you may get a slight freeflow between breaths). In that case, turning the knob in a turn or two should do the trick.

A violent freeflow occurring when you purge the reg or if it falls in the water with the mouthpiece facing up occurs and is sustained for different reasons related to the venturi effect that is caused by the air leaving the regulator - which essentially lowers the pressure in the second stage case and keeps the diaphragm depressed. In this case, restricting the flow, by either turning the reg mouthpiece down in the water or placing your thumb over the mouthpiece will slwo the flow, increase the pressure in the case and cause the diaphragm to return to the normal position and stop the air flow.

But don't worry about not knowing that - it is not intuitively obvious especially if you just upgraded from a lower performing regulator where the venturi effect is not sufficient to sustain a freeflow. Also, with a high performance second stage, lightly depressing the first stage works fine to test the reg and is less likely to start a sustained freeflow than a full depression of the purge.

OceanicRocks · Oct 31, 2007

DA Aquamaster:
There is a difference between stopping a slight freeflow caused by the regulator being adjusted slightly too light (which may occur with the knob all the way out on the surface or even with it in a bit in a face down position in the water where you may get a slight freeflow between breaths). In that case, turning the knob in a turn or two should do the trick.

A violent freeflow occurring when you purge the reg or if it falls in the water with the mouthpiece facing up occurs and is sustained for different reasons related to the venturi effect that is caused by the air leaving the regulator - which essentially lowers the pressure in the second stage case and keeps the diaphragm depressed. In this case, restricting the flow, by either turning the reg mouthpiece down in the water or placing your thumb over the mouthpiece will slwo the flow, increase the pressure in the case and cause the diaphragm to return to the normal position and stop the air flow.

But don't worry about not knowing that - it is not intuitively obvious especially if you just upgraded from a lower performing regulator where the venturi effect is not sufficient to sustain a freeflow. Also, with a high performance second stage, lightly depressing the first stage works fine to test the reg and is less likely to start a sustained freeflow than a full depression of the purge.

thank you all for making me feel better even though I caused quite a scene...

how do you lightly depress the first stage? did you mean the second stage?

Ed Palma · Oct 31, 2007

Hey Coral, yep, sounds like your reg is just fine and highly tuned.
As usual, DA's explanation was the best. I think he was referring to lightly pressing the opening of the ambient chamber to simulate going to a deeper depth.

IceBergSlim · Oct 31, 2007

Most regs come with all kinds of knobs and switches. They are there so you feel good about buying them.

Just dive the reg and see what happens. If it free flows often the problem may be due to temp/ ice or a lack of maintenance. (not likely on a new reg)

It kills me to see all the knob twisting people do to get their reg "Tuned".

Ed Palma · Oct 31, 2007

Actually, I find that the knobs DO work. I was servicing my friends regulator, it came with adjustment knob, and I could really feel a difference in the ease of breathing when adjusted to very light pressure. Additionally, those knobs help out because before storage, I could turn it way out to reduce the amount of groove formation in the poppet seat.

Personally though, my 2nd stage is an old conshelf XIV, with the brass box and no knobs. I get along just fine without them, but I can see that they would be a plus to some people.

philmayer · Oct 31, 2007

It happens all the time. I've done it plenty of times in front of students!

Check the predive switch, then the adjustment knob. If you're in the water, turn it mouthpiece-down.

Be sure to rinse the regs well each time you use them. My AirXS2 is a bi*ch about it.

As an example of why you need to learn to retrieve your reg in one of the classes a few months ago my instructor pulled my octo D4 loose and free-flowed it so all the students could see why the skill was important. And to show how goofy their DM looked trying to retreive it.

jaybombs25 · Oct 31, 2007

Sorry to burst your bubble Mr. Ice berg but the knobs DO work. it increases or decreases the sensitivity of the diaphragm. On the surface you want it on the least sensitive (reduces the chances of free flow). Once at depth turn the knob and make it a little more sensitive and you see a BIG difference in ease of breathing. I don't know if people "Tune" their regs, but a simple few turns on the surface all the way off and one or two at depth to make it just right is what most divers go through with most regs.

regulator free flow

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