Regulator freeflow? How to deal with this?

After reading the Near Misses forum (great learning tool for noobs, imo), it occurred to me that I ought to post a question about what I guess is called regulator freeflow. As a noob myself, I've been on 9 dives with 4 different operators in 4 different countries. I mention this because despite having so few dives under my belt, I've had regulator freeflow issues with 3 out of the 4 operators (all rented equipment).

First, let me make sure I understand the term "freeflow" properly. This is when the 2nd stage gushes out air despite the user not inhaling, right? So I've had this happen twice when we were checking gear on shore and twice while floating in the water (either at the beginning or the end of the dive).

It was not cold, and I would think regulator maintenance wouldn't be the likely culprit since it happened with 3 different operators, all in different countries. But whatever the cause may be, if I have this happen again, what should I do? Our DM/Instructor seemed to slap the mouthpiece against their palm to get it to stop. On one occasion (maybe 2) this didn't work, and they turned the valve off and on to get thee regulator working again. One time, they swapped out the regulator.

Is this a problem that people have a "quick fix" for (ie. is tapping the mouthpiece a standard routine?), or is this a more serious problem? Since I don't want to rely on my DMs to fix these glitches for me, I'd like to know what the SOP should be under these circumstances. Also, have I just been unlucky in experiencing a serious problem so often (relatively speaking) or is this a common, minor problem that people deal with all the time and resolve in a few seconds?

Stick your tongue in the hole

You experience is really unusual. I have nearly 1000 dives and have never experience regulator free flow. My first suggestion is that you buy your own quality equipment and have it serviced regularly. That is the best prevention. If you do experience regulator free flow, I suggest you switch to your alternate air source first before trying to solve the problem, assuming you are in the water. Then you can attempt to stop the flow through pushing the purge valve once or twice. Sometimes the simple act of facing the mouthpiece downward will stop the flow. Slapping the regulator may (but at you pointed out) does not always stop the issue. In re-reading you post I sense that your free flows happened at the surface at least one time. If that occurs and you cannot correct it, turn off the air, and change the regulator by removing the defective one from the first stage and replacing it with a working one. If upon turning on your air while still above water you have a free flow, push the purge valve once or twice. If that does not work, submerge the regulator to get it wet, and that may do it. But let's go back to the first suggestion: Get some quality gear and maintain it properly and reduce the risk of a real problem.
DivemasterDennis

Covering the mouthpiece hole sometimes works. If it's not a full-blown free-flow and you get it fast enough, you can sometimes just turn the mouth piece over IE turn it down instead of up. Other than that, if you can't get it to stop, banging sometimes works. The next option is turning the gas off and using your buddy's octo then maybe trying to turn your air back on.

A lot of 2nd stages these days have dials on the side that allow you to adjust (slightly) how easily the air flows. This is something you should check out before you get in the water. I keep mine set to the "hardest" level (most work to get it to flow) which should help reduce free flows a little bit.

If you're going to dive a lot, my opinion is you should buy your own regs and maintain them well. I bought a lot of used equipment cheaply (including 5 or 6 regs) that I have serviced by a shop or am servicing myself.

Thank you for the advice.

Actually, all of these problems have occurred while at the surface (either floating on the surface or on land). I recall now that at least once, this happened when I used the purge button to test the set-up.

So it appears that my own regulator is on the horizon if I'm to continue diving. Are there specific brands that have a reputation for these kinds of problems? From reading these forums, the general consensus seems to be that any mid-range regulator would be fine, but I've had other people tell me that certain brands tend to be flaky. And considering my luck, I should probably get the most reliable one for the price, hehe.

Cosmographer:

So I've had this happen twice when we were checking gear on shore and twice while floating in the water (either at the beginning or the end of the dive).

Click to expand...

I think this part of your question is the key . While some regs are less susceptible to free flow at the surface than others, it has to do with the unequal amount of water pressure being exerted on the purge valve when the second stage submerges. Pick up the reg and place it in the water mouthpiece side down. This prevents free flow at the surface virtually every time.

Slight hijack:

What would cause a regulator to free-flow at depth? Does it usually only happen while descending / going past certain depths (to trigger uneven pressures somehow)? Temperature or dirt making it stick? When it does happen at depth, is it more often to a primary or a secondary reg, or is it equal odds? Any other good info I should know but probably don't?

Obviously I've never had this happen (well, at the surface for sure, but I'm not worried about that), so I don't know what to look for and/or really what to do (besides hopefully getting a buddy's octo in my mouth and going to the surface). But what if there's no easy access to the surface?... dose this pose a "holy sh*t - I'm going to die" threat?

There is some misunderstanding of what freeflows are. There are 2 basic reasons a reg freeflows, equipment failure and...the one that takes a little understanding- normal operation. I know this is counterintuitive. Equipment failure is pretty obvious but the freeflows you are describing are actually normal operation and believe it or not, if your does NOT freeflow as you describe it NEEDS service. Most modern second stages are designed so the regulator provides a venturi assist as you breath. Pressing the purge button or allowing the second stage diaphragm to be pressed by allowing it enter the water mouthpiece up starts the process. As air flows into the second stage, it is directed toward the mouthpiece. By design, the flow of air causes a slight vacuum to be created inside the second stage, pulling the diaphragm in and "assisting" the diver. In a divers mouth, as soon as the diver stops inhaling the air pressure builds up slightly which pushes the diaphragm back and the flow stops. When the reg is not in the divers mouth and air flow is started the flow in a reg creates sufficient vacuum to pull the diaphragm in by itself. Once started, the process feeds on itself, more flow means more vacuum and more vacuum pulls the diaphragm in farther, creating more flow and more vacuum. This process continues until the valve is fully open and the flow will continue until something stops it by increasing the pressure on the diaphragm in the second stage- your hand over the mouth piece or you put the reg mouthpiece down in the water. This process is normal and a reg should freeflow in this manner. Out of the water, if it does not freeflow when the purge is pressed there is a good chance the second stage is not properly adjusted or the first stage is not supplying sufficient volumes of air for some reason, both mean the reg needs service. Many second stages have operator adjustable venturi controls which will reduce the effect of the venturi to the point that is will no longer have sufficient effect to pull the diaphragm in (and no freeflow) but if the control is set to provide venturi assist, it should freeflow once flow is initiated. Bottom-line, out of water freeflows you are discribing are not an equipment problem, it's an operator problem.

The question is " Is it operator failure or gear failure? "

Any regulator that is working to a normal specification will Free Flow when you put it in the water on the surface with the mouthpiece facing up. Simply turn the mouthpiece facing down or create a back pressure by putting your finger or mouth over the mouthpiece.

Regulators that are set closer to their "cracking point " either intentionally or due to lack of maintenance may Free Flow when you push the purge button or when the tank is turned on.

Higher Performance regulators have an adjustable Venturi Initiated Vacuum Assist ( VIVA ) and an adjustable inhalation effort.

We use the Scubapro MK25/S600 reg. in our training program. It has both of the above features.

We train our students to have the VIVA turned down while they are doing their skills. We show them that when the VIVA is turned up in the dive position and the adjustment knob which controls the inhalation effort is all the way open the regulator will Free Flow when they push the purge cover and it is not in their mouth.

This Free Flow is a normal function of the regulator when it is out of the diver's mouth and there is no back pressure. You simply need to create a back pressure to stop the Free Flow by putting it in your mouth, putting your finger over the mouthpiece or turning down the VIVA.

This Free Flow actually demonstrates how effective the VIVA is. As the diver goes deeper the gas becomes denser and any reg. become harder to breath. The VIVA deals with this problem by assisting the divers breathing.

In a previous post, it was mentioned to have the adjustment knob which controls inhalation effort turned all the way down in the hardest position. This knob allows the diver to adjust the spring and increase the actual resistance of breathing.

We recommend that you have this adjustment all the way open so that the diver is not having to work to breath. This adjustment allows the diver to dial-in exactly how they want their reg. to breath in different situations. The idea that you can use less air by making the reg. harder to breath is incorrect.

The function of this adjustment is to allow the diver to de-tune the reg. while swimming against a current or other situations.

Also, as the reg. gets out of tune due to use and lack of maintenance the reg will go past the " cracking point " and Free Flow. The diver can externally adjust the reg by cranking down the adustment knob.
The reg. will not Free Flow, but will breath harder. This reg needs to be serviced to bring it back into spec.

If the rental reg. free flows due to lack of service, then do not use it. Hitting the rental reg. with your hand or a hammer is not the solution. The FREE FLOW will only get worst. Regs. are fail safe, they give you air as opposed to shutting off.

There have been U.S. travel warnings about how dangerous SCUBA rental gear is in some countries.

As far as recommendations for regs., the Scubapro MK25/S600, MK17/A700 or the MK25 or MK 17/ G250 in yoke or DIN are excellent choices.

Also, the NEW MK11/C300 is an excellent value in a mid-price range.

If you are going to be a diver, then you need to commit to the sport and own your own gear!

Freeflows and the order of diagnosis/resolution. I'd tackle them in this order, to determine the cause/severity...

2nd Stage:

- Invert the regulator (mouthpiece downwards).
- Plug the mouthpiece (finger or tongue etc).

1st Stage:

- Breathe from freeflow regulator (as per Open Water Course skill) and ascend.
- Breathe from buddies AAS and possibly consider shutting down your own tank (less stress from bubbles). Ascend. You might be able to re-open your tank after a short while (if freeflow caused by freezing).