Cold, stressed & freeflow regulator

[peterbe]

I think I learned an important lesson yesterday. First some background...

Last weekend I was diving in a fresh water scuba park in Texas (CSSP). Water temp was around 50F and I was wearing a 7mm sleevless vest with integrated hood with a full 3mm w/s over the top - so 10mm over my core, 3mm on arms & legs. The other divers with me were diving dry. I have around 40 dives.
I was comfortable in the water for the first dive but beginning to chill a little on the second. On the second dive I noticed that my 2nd stage was emiting bubbles even when I was not exhaling - I didn't register this as a freeflow as I thought a freeflow was more explosive than that. It was intermittant and I
completed the dive. I had the reg. serviced that week (Atomic B2 which I bought new).

Yesterday, conditions were slightly colder (49F) and the air temp was in the 40s and a bit windy. Same exposure protection, I made a 45 min dive with no incident. I was comfortable until we made our s/stop and I practiced some skills on a platform - then I began to get cold. We had a 2hr+ s/i and made a second dive. I was still a little chilled at the start
of the second dive. Again I noticed my 2nd stage freeflowing. I took it out of my mouth and waved it around and it stopped - this happened several times (I never thought to breath from my integrated octo/inflator!). The freeflow and (I guess) the cold had my anxiety level rise and I began having trouble maintaining buoyancy. After 3 or 4 of these incidents I came to the surface and swam back to the dock on the surface. Dive time was 30mins.

My SAC rate on the first dive was around .7 (which has been average for me this winter). On the second dive it was 1.35.

My buddy (a very experienced tech. diver) said that the cold was having me stressed, breathing too hard, and overloading and freezing the reg. His advice, learn to breath slower/deeper and dress more warmly!

I thought I'd share this and invite any other tips/advice.

[openmindOW]

Thank you for your post.

If I may, I have a couple of questions.

1) What kind of First Stage did you have? Enviro-sealed? Make, Model?

2) What kind of Second Stage did you have?

3) Do you own the gear or was it rental?

4) If you owned it, when was it last surfaced? And, who serviced it?

5) You say the water temp was about 50 F. Can you be a bit more specific? Did you or your buddy happen to have a computer with a thermometer?

6) Have you tried the same rig in a pool with, of course, warmer water?

7) You said the free-low stoppped when you shook the Second Stage. That doesn't sound like a First Stage freeze-up. Is it possible that the reg might simply need an adjustment?

Thanks.

[simcoediver]

What your reg was doing was not a freeflow,theres something else wrong if its emitting bubbles as you described. Take it back to get serviced properly,you have an internal oring problem.
50 degree water is not cold enough to cause a freeflowing reg.
Get yourself a drysuit, you will never go back to diving wet in cold water.

[dave4868]

Again I noticed my 2nd stage freeflowing. I took it out of my mouth and waved it around and it stopped - this happened several times (I never thought to breath from my integrated octo/inflator!).

My buddy (a very experienced tech. diver) said that the cold was having me stressed, breathing too hard, and overloading and freezing the reg. His advice, learn to breath slower/deeper and dress more warmly!

I thought I'd share this and invite any other tips/advice.

It's a slight freeflow, not uncommon just after a servicing where the cracking pressure (ease of breathing) was adjusted too close to freeflow and/or the regulator was not cycled enough to stabilize the seats and intermediate pressure.

It probably requires a simple adjustment to the second stage. Your LDS should be happy to do it for free.

I doubt your regulator was freezing up in those temps.

Dave C

[DA Aquamaster]

I agree it is most likely a second stage adjustment issue - with one possibility we'll discuss later.

50 degrees is cold enough in some cases for a reg to freeze, but you'd have to provoke it.

At 40 degrees, taking a reg with slight freeflow out of your mouth and waving it around would probably count as provoking it and the most likely result would be a full fledged freeze flow.

That said, a second stage freezes up because the air passing through it expands about 140 psi and has to gain energy in order to expand (as the molecules need to move faster to take up the greater volume). It gets this energy in the form of heat drawn from the regulator parts that are in contact with the expanding gas. The reg parts in turn either have to draw heat from the surrounding water, or they will cool well below freezing. If that occurs any water or moisture inside the reg will freeze onto those parts and the ice that accumulates may cause the reg to fail open or closed. With so many mostly plastic regs floating around many of these internal parts are well insulated from the outside water so this heat transfer does not occur.

So...it is possible that the slight freeflow was occurring as small crystals of ice were forming on the poppet, seat, or other parts involved in opening and closing the valve that prevented the valve from fully closing, creating a small leak. In this case taking the reg out and waving it around let water into the second stage where it could then warm the parts and melt the ice.

The downside here is that it also lets water in the second stage, some of which remains there in contact with parts that will get cold one you put it back in your mouth, purge it and continue to breathe off it. I other words, if this was occurring, you got away with it only because the ice accumulation was minor and the parts were just barely below the freezing point. If you tried the same thing in 40 degree water, the likely result would be bubbles everywhere.

The same effect occurs in the first stage, where the reg cools and the water in the ambient chamber freezes on the colder metal parts and eventually form an abstruction that prevents the valve from closing after an inhalation - this then produces excess intermediate pressure that has to vent through one of the second stages, and that rush of air creates more ice in/on the first stage as well as quickly causes ice formation in the second stage which causes it to freeze as well.

As an aside, the little second stage shut off valves work fine if the second stage freezes and would allow you to shut off a frozen second stage, so you could take it out wave it around and generally not use it for a few minutes until it thaws. But they are dangerous in the case of a first stage freeze up if you have one on each second stage, as closing off both second stages leaves the excess intermediate pressure with no place to vent other than through your BC or drysuit inflator (an uncommanded inflation) or through a burst LP hose. In other words, if the first stage freezes up the only solution to stopping it is to shut off the gas at the tank valve until it thaws.

[peterbe]

[QUOTE=openmindOW;4281535]Thank you for your post.

If I may, I have a couple of questions.

1) What kind of First Stage did you have? Enviro-sealed? Make, Model?
2) What kind of Second Stage did you have?
3) Do you own the gear or was it rental?
4) If you owned it, when was it last surfaced? And, who serviced it?
5) You say the water temp was about 50 F. Can you be a bit more specific? Did you or your buddy happen to have a computer with a thermometer?

It's an Atomic B2 with about 40 dives on. Last serviced last week by my local dive shop equipment specialist (certified to
service Atomic regs). It is NOT enviro. sealed.
I bought the whole rig new 18 months ago.
Water temp was 49F

6) Have you tried the same rig in a pool with, of course, warmer water?

Yes. And in the warm (tropical) salt and fresh water. Never had
this problem before.

7) You said the free-low stoppped when you shook the Second Stage. That doesn't sound like a First Stage freeze-up. Is it possible that the reg might simply need an adjustment?

Well. I don't know.

[jeckyll]

Couple of other questions.

Did you buddy ascend with you when you called the 2nd dive? Was he aware of the fact that you were having problems, either due to you mentioning it before or from observing you?

As for the reg, take it back to the tech and make him fix it

[Garrobo]

A two-hour SI? At 49 degrees that would freeze me up. Especially if there was any wind blowing.

[Piccola]

I just posted this:
Just to add my 2 cents and coincidentally I was just discussing this on another board. I have a scubapro mk17/s555. I dive in cold NE waters. I had my regulator freeflow on me once. I wrote a big response on it here but can't find the post. In any case looking back on it I did all the wrong things, I dragged my second stage in the water and then added my breath to the mix and it wasn't properly adjust for our water temps. Someone here question the passing of small bubble vesrsus and explosive event, it is an explosisve event when it went into freeflow. I believe the water temp was 36 degree at 50+ feet and there was still snow on the ground. Another CRITICAL thing to mention was it was the first time I used the gear. The regulator flows are set by the factory in California for their condidtions which are not nearly as cold as ours. That is not the user settable flow control on the outside of the regulator, I had my LD shop adjust it and it never happened again.

I agree with Da Aquamaster's reply. I have since added shutoff's to my gear, against some recommendations. Sometimes a freeflow can easily be resolved by pushing your thumb into the mouthpiece, assuming of course it is a second stage freeflow. The thing is not to panic, you can continue to breathe normally as you head to the surface and you can suck off of your buddy if you run out of air. They are always happy to share! The other thing is to inflate your BCD if possible at the surface to keep you and all your prized gear above the waterline.

Hope this helps