Free flowing reg and what should one do?

[LollyO]

I was just reading a thread about a free flowing reg. I seem to remember that discussed in my training, but thats been a long long long time and it hasnt come up since.

What causes a free flowing reg and what you should you do if it happens to you?

 

[antattack]

Your regulator will flow air when pressure on the diaphram is low enough to open the demand valve. This happens when an air bubble in the regulator escapes and pulls on the diaphragm a little. Once that happens, the regulator flows air and subsequent bubbles escaping create a low pressure gradient on the demand side of the diaphram, holding the valve open until pressure is somehow sufficient to close the demand valve.

The easy way to restore pressure is to capture an air bubble in the regulator so that it cannot escape. To do this, all you need to do is position the regulator so that the mouth piece is face down.

At the surface, position your regulator so that the mouthpiece is face down to prevent free flows.

Once you are under water, the bubble will slowly escape and ambient pressure of water will hold the valve closed until you hit the purge button.

Many modern regulators have a switch that allows you to increase cracking pressure of the demand valve. This will help prevent free flows at the surface.

That's my understanding. Now scuba board members, tune up my comments.

 

[TSandM]

A freeflow will occur whenever the demand valve on the second stage is stuck in the open position. This can occur because of pressure differentials, as when you first immerse the second stage and do it with the mouthpiece up. It can also occur because of debris in the second stage, or a stuck purge cover. The most difficult freeflows are the ones which occur due to high intermediate pressure, because you can't fix them by messing with the second stage. First stage freeflows can be caused by regs which are out of service, or by freezing that happens with high airflows in cold water.

You can breathe off a freeflowing second stage, either by holding the mouthpiece loosely and allowing the excess flow to escape, or using the method you learned in OW, which is tilting the reg and breathing off the edge of it. However, it takes about 90 seconds for a full-blown freeflow to empty an 80 cf tank from full (and even less if the tank was partially used before the freeflow happened). Therefore, except in very cold water, you are almost certainly better served to request gas from your buddy, and then have time to make a well-controlled ascent. (In very cold water, the extra demand on the buddy's regulator may cause HIS to freeflow, too -- so for ice diving, having your own redundancy, for example by using double tanks, is a better strategy.)

 

[oreocookie]

Like antattack mentions, if there's less pressure on the mouthpiece side of the second stage diaphragm, the reg will freeflow. Turning the mouthpiece downward will stop the freeflow by equalizing the pressure differential. A reg could also freeflow if it freezes up or something breaks or gets jammed. Turning the mouthpiece downward in that case is not going to help. You should have been taught how to breathe from a freeflowing reg in your OW class, have part of the mouthpiece in your mouth, part out, so the freeflowing air will spill out of your mouth and sip the air like you would drinking at a water fountain.

 

[Doc]

All as above plus: Give it a hard whack on the palm of your hand.

And here's the big one... if that fails, alert your buddy for potential OOA situation, then ascend immediately but slowly.

 

[redacted]

There is a class of freeflows that you will not be able to fix UW. Lynn touched on it when she mentioned high IP forcing the 2nd stage seat open. That is usually associated with some type of component failure in the 1st stage. A failure of certain components in the 2nd stage will have the same effect - spring, LP seat, and the orifice o-ring (and others depending on the design). So it is good to know how to remedy a FF but you must also be prepared to breath from a FF reg or turn to your alternate air source.

 

[windapp]

One thing to note is that the fast majority of free flows are caused by the first stage. Knowing this, you should never use your octo in a free flow. If you do, and it is the first stage, you will have two free flowing seconds instead of one.

If you are my buddy, within seconds of me realizing you are having a freeflow, you will feel my hand grab your bcd. You can continue sipping off of the freeflowing regulator as we ascend, assured that there is a correctly oriented octo tucked under my pinky finger.

 

[fjpatrum]

One thing to note is that the fast majority of free flows are caused by the first stage. Knowing this, you should never use your octo in a free flow. If you do, and it is the first stage, you will have two free flowing seconds instead of one.

If you are my buddy, within seconds of me realizing you are having a freeflow, you will feel my hand grab your bcd. You can continue sipping off of the freeflowing regulator as we ascend, assured that there is a correctly oriented octo tucked under my pinky finger.

I've never heard this information before. Why do you say the vast majority of free-flows are first stage? The only free flows I've ever seen or heard of second hand (except here on scubaboard) have been second stage free-flows. I've not met anyone in person who has had a first stage free-flow.

 

[Diver0001]

I was just reading a thread about a free flowing reg. I seem to remember that discussed in my training, but thats been a long long long time and it hasnt come up since.

What causes a free flowing reg and what you should you do if it happens to you?

You got some good technical answers already so I'm going to take it down a notch. Look at it like this:

A freeflow is when your regulator keeps pumping out air even when you're not breathing in. In some cases the amount of air is small (a little bit of a "hiss" and some extra bubbling) and you'll have lots of time to deal with it as described above. HOwever, there are situations where something goes drastically wrong and the regulator can freeflow "violently". The worst case scenario is when something breaks inside the 1st stage (the bit you screw onto your tank) that can cause the regulator to freeflow so hard that you can't even put it into your mouth. Likewise if it was in your mouth at the time, a first stage failure could cause so much air to push through the regulator that it will blow it right out of your mouth, which can be quite a shock.

In order to handle these situations, I tell people to apply the "ABC" rule.

A = air. Whatever happens make sure you don't run out of air. In the worst case scenario I mentioned above, you'll have to look to your buddy and give them the OOA sign and make use of their octopus. You can also breathe out of a violently freeflowing regulator by putting it 1/2 in your mouth and "sipping" air out of the stream of bubbles it generates. You probably did this in your OW training but it sounds like you may have forgotten.

If you buddy is not in the neighbourhood then you really only have one choice, which is to GTFO to the surface using your own reg and "sipping" out of it like I mentioned. In the worst case a total failure could cause the regulator to drain a full tank in about 2-3 minutes, give or take, so you have enough time to surface. Just make sure if you have to do this that you get on with it and get to the surface on time. Keeping your tempo under control is nice but getting to the surface before the tank is empty is a lot more important.

B = buoyancy. If your buddy is there to help you then take a moment after you get the octopus to get sorted before doing anything. Make sure you hold on to each other and make sure you get your buoyancy synchronized so you're still "diving" and not making an unintended ascent or sinking. This step is to ensure that once you have your air supply sorted out that you take a moment to calm down and regain control. Anything you do after that will become a lot easier if you do.

In the case where you make an emergency ascent to the surface with a free flow, buoyancy means to throw off your weights so you don't have any chance of sinking again. Don't forget, if your BCD isn't holding you up and your tank is empty then you can become screwed in a big hurry so don't forget to dump the weights and make SURE that once you get to the surface you STAY there.

C = communicate. Make a plan and do it. If you use your buddy's octopus then you may signal for them to turn off your tank to stop the free flow (and the chaos of all of teh bubbles) or to signal to surface or whatever. At this point you're working as a team under control (because you have your air and buoyancy sorted) to make a plan to end the dive safely and under control.

Hope that makes sense.

R..

---------- Post Merged at 07:54 PM ---------- Previous Post was at 07:45 PM ----------

I've not met anyone in person who has had a first stage free-flow.

The "bubbling" type can be caused by IP creep in the first stage but generally they're caused by the second stage being out of tune or poorly maintained.

I've seen a lot of free flows over the years and to date all but 2 of them were caused by the 2nd stage somehow sticking open (freezing or getting gunked up).

The other two were one case of a first stage that froze open during an ice dive, causing a violent free flow (thankfully on the surface but it was -15C and it was not totally unexpected...) and one case of someone whose second stage had somehow become unscrewed from the end of the hose during a dive.

R..

 

[fjpatrum]

---------- Post Merged at 07:54 PM ---------- Previous Post was at 07:45 PM ----------



The "bubbling" type can be caused by IP creep in the first stage but generally they're caused by the second stage being out of tune or poorly maintained.

I've seen a lot of free flows over the years and to date all but 2 of them were caused by the 2nd stage somehow sticking open (freezing or getting gunked up).

The other two were one case of a first stage that froze open during an ice dive, causing a violent free flow (thankfully on the surface but it was -15C and it was not totally unexpected...) and one case of someone whose second stage had somehow become unscrewed from the end of the hose during a dive.

R..

Exactly, I was wondering if maybe windapp just meant second stage and typed first stage or if there was something I hadn't heard about before. Having been an avid scubaboard diver for the last two years (if not a very active actual diver) I hadn't even read about a lot of first stage free-flows. Most I've read about and all I've experienced or seen first hand were always second stage... just wanted some clarification for my education.