Freeze- Up & Free Flows

[Darnold9999]

Yesterday while at the quarry, a group of us (4) decided to do a deep dive. The quarry reaches depths of 115 ft with temperatures in the low 40's below 60 ft. We decided that 1 buddy pair go one way & the other would go another. I was diving double 108's & my buddy was diving a single steel 104. We descended without much problem. The other team leveled off at about 70 ft & started on their way. I am not sure what size/ type tanks they were diving only that they were singles with no redundancy- which IMO is crazy in that environment;

I am a little puzzled by the "crazy in that environment" statement. They were diving single tanks at 70 feet - possibly going to 115 with a buddy. I am missing the crazy part of that plan. I am pretty regularly diving 70 to 100 feet with a single tank and don't view it as even remotely crazy. Low 40 degrees is cold but not outside of normal. What is the crazy part that I am missing? Personally I view shlepping doubles around to do rec diving as crazy but that is a whole other topic

 

[tstormdiver]

The "crazy" part comes from not having some sort of redundancy (doubles, pony,... something) for one's air supply. In that cold water, it is usually not a matter of "if" your regulator will have a free flow, but "when" it will. I had almost 200 deep dives there before my free flow.

From statements made earlier in the thread, the diver's tank was full as we were in the beginning of the dive. He was at no time out of air. The only reason I offered my primary was because I was planning to shut his air system down to let it thaw & then give it back to him. The free flow started at minute 5 of the dive. With that until I broke the surface after doing the deco my computer had prescribed, the dive was 9 minutes total.

captndale- I could not put my regulator in his mouth as he still had his in. He breathed his free flowing regulator all the way to the surface.

Why did he not react? I honestly can't say. I believe it was a combination of narcosis (tends to be much worse in colder water), perceptual narrowing from rising stress & some inexperience in that kind of diving. This diver has probably a little over 100 dives & maybe a dozen deep dives at this quarry. He was taught deep diving in the warm Caribbean. It is worlds apart from the cold water in the quarry. Can one adapt to it? Of course you can, but there are thing to consider in each environment that is not found in the other. I think this diver may be a little too complacent, careless (I don't know exactly what to call it) about diving this quarry. He has been encouraging newer divers to dive deep there. One of them was the diver who had the other free flow- that diver, I found out today, has not had any training in deep diving. I can only imagine what may have happened if those 2 had been diving deep together & had that happen.

I am not saying that no one shouldn't dive deep there, but that if you do, you should be prepared to handle what can be problems down there. It is not a very forgiving environment.

 

[stakanak]

I have a feeling I am going to be verbally punished for this question but here goes:
If free-flow is an inherent problem, especially in cold water circumstances, why do we not have an "off valve" in front of the second stage so we may shut off the flow and immediately go to our back up without shutting the whole system down?

 

[tstormdiver]

It seems to be more of a problem with high performance regulators (which all of us were using), though any regulator can free flow, if conditions are right. Most of the time the free flow comes from the 1st stage freezing up, not the second stages, so even if you shut 1 second stage down, the other would then start free flowing also. Not a dumb question by far, something a diver needs to know.

 

[TSandM]

The freeflows that occur in cold water are most often due to the first stage freezing, so that the orifice can't close and regulate the pressure coming through to the second stage. The second stage freeflows because it's not designed to retain that much pressure; in fact, it's a safety valve to prevent blowing the hose. So, if you had a shutoff valve on the second stage and used it, most likely your other second stage would begin to freeflow, or if not, something more dangerous would happen, like uncontrolled BC inflation.

 

[Ayisha]

Something to also consider in extremely cold water conditions is that you use a cold water reg. Typical warm water regs will often freeflow in very cold water and don't really cut it here in Ontario, which is similar to what you're describing. A reg that is designed for cold water, though, can be used in both cold and warm water diving. High performance regs often freeflow here as well, but that is usually because they are not adjusted appropriately or do not have the environmental kit installed. Good reg maintenance by an excellent technician is a must.

 

[tstormdiver]

I service my own regulators. I do not have an environmental kit in them because the kits will lessen the performance of the regulators & I need the performance in them at times for the diving I do. I dial the adjustment knobs back & am very careful to watch my breathing patterns when I'm in cold waters.

 

[Troutmaster]

I dive sealed first stages and have not had a first stage freeze. Ever. Most of my diving is in cold water (32 to 40 degrees) I have had second stages freeflow, like most of you my high perf regs are much more prone to locking up then lower perf ones. One most of the freeflows I have had, just like was said before, the reg started to "dribble" air before it locked up.

In my opinion (and it is only that) diving a 1st stage not designed for cold water use is unsafe in cold water. I am curious what performance is lost with a sealed diaphram 1st?

 

[Thalassamania]

Almost no performance is lost, a tiny increasing in the cracking pressure is about it. As far as using a 1st stage not designed for cold water use, I was curious about that and in the high arctic on a series of blue water dives I used an OCEANIC OMEGA II (piston, unsealed). As long as I was careful not to breathe off the reg before I submerged it preformed fine, but one breath on the surface, or even just BC or suit inflation and then it would freeze up when I started breathing off it underwater.

 

[Troutmaster]

Thal., I am guessing you have a pretty low sac rate and do not overbreath your reg, 2 things that tend to cause more problems with freeze up. I know you have a few thousand more dives than I do and I am curious if you ever had an air share situation with an unsealed piston in really cold water? If you have and it did not freeze with that much demand, I don't think it ever will.

I have also experienced the "in air but not water" freeze ups you refer to (had to get out of the habit of the "check breath" with wet regs before submerging).

In my limited experience seeing a few unsealed firsts freeze up, I just don't want to mess with it.

I guess my point is this, sealed diaphrams are available, why not use them in cold water (is there a disadvantage I am missing?)