Cold Water Free-Flow Survey?

[MrVegas]

As far as I can find, despite all of the discussion and some published extreme condition testing, there has never been a real survey of experiences with cold water regulator free flows (at least publicly available). I have never had one personally, but I thought I would finally go ahead and ask for experiences of those who have had or directly observed free flows in cold water due to freezing. (Cold water generally defined as under 50F\10C.) If you are willing to share, here are the questions:

1. What was the water temperature, air temperature, and depth at which the free flow occurred?
2. What was the make, model, and style of the 1st and 2nd stage of the regulator? (If not wanting to share brand information, then what type or style – e.g., balanced or unbalanced piston, diaphragm, environmentally sealed or not, compact or normal 1st or 2nd stage, plastic or metal 2nd stage, adjustable, venturi adjustment, etc.)
3. Other relevant information – venturi set to dive or pre-dive, purge button depressed during dive, do you know whether free flow started in 1st or 2nd stage, etc.?
4. Anything else you want to share regarding conditions or preparation, reg servicing\adjustment, or techniques for cold water dive that could have led to incident?

CAVEAT: for anyone reading – this would still be largely anecdotal evidence, not a true statistical study and would not account for factors like total number of dives on a particular regulator. (For example, if sealed diaphragm regulators are used for 99% of cold water dives, they might logically account for more stories of freeze-ups.)

 

[OrcasC205]

You may want to note the salinity (fresh- or salt-water) when the free-flow occurred since it will affect the freezing point.

Regarding your study, despite having dove in fresh water down to 43°F and salt water down to 45°F (primarily with balanced piston first stages), I haven't seen a free flow.

 

[nadwidny]

Way too many parameters for me to remember but here we go.

Pistons. Sherwood blizzard (salt), S'pro mk20 ( few times in fresh). Freeflows because of 1st stage freezing Water temps were probably around 3C.

Diaphragms- never seen it. Even that time I used a Poseidon 1st that was encased in 1/4" of ice when I got out after 30 minutes (fresh water)

 

[L13]

I have had a buddy's regulator free flow 3 times in ~42F fresh water at ~80 ft. 2 different buddies, 2 different regulators. In both cases the regulator was an SP Mk25, one with a G260 and the other with a C370, that had been recently service. I suspect that the recent service was more significant than either the make or model of the regs.

 

[Tanks A Lot]

You may find the two attached files interesting.

The extract from the NEDU report is very dated (1987), but still an interesting read. It clearly shows which designs are/were better at resisting freeze ups. Things have changed over the years and engineering has moved forward, but I nevertheless find it illuminating. The full NEDU report is too big to attach here.

DiveLab ran a fantastic test in 2014, explaining clearly why and where the freezing happens.

 

[MrVegas]

You may find the two attached files interesting.

The extract from the NEDU report is very dated (1987), but still an interesting read. It clearly shows which designs are/were better at resisting freeze ups. Things have changed over the years and engineering has moved forward, but I nevertheless find it illuminating. The full NEDU report is too big to attach here.

DiveLab ran a fantastic test in 2014, explaining clearly why and where the freezing happens.

I had actually seen those studies before. I guess what I am trying to get at is a survey of people that have had free flow experiences on actual dives. How cold, how deep, and what kind of 1st and 2nd stage? As far as I can find, that has not been done.

Thanks to those that have responded!

 

[Bigbella]

I have never had one personally, but I thought I would finally go ahead and ask for experiences of those who have had or directly observed free flows in cold water due to freezing. (Cold water generally defined as under 50F\10C.)

Nor have I, even though I had frequently engaged in ice-diving in both freshwater and cold (saltwater) diving in the low single digits celsius, in British Columbia and elsewhere. I would attribute that lack of free-flow issues, to having been quite careful to preassemble and test breathe all of the equipment, either only in a heated, indoor environment if that were at all possible; or, even a warm truck interior -- and never out in the elements, prior to hitting the water.

Purge buttons were seldom or just gingerly used.

My equipment at that time, were "winterized" Poseidon Cyklon 300s (unbalanced 2980 first stages) and Cyklon 5000s (balanced 2950s) regulators with metal second stages, with either vodka-filled rubber caps or metal antifreeze versions with alcohol / glycerine mixtures -- and while I did experience some minor icing, especially with the increased air volume of positive-pressure or "OP" full face mask use -- it, luckily, never reached the threshold of a free-flow.

Even though any regulator is capable of freezing given the right-wrong circumstances, the later "naked-as-a-jaybird" MK3 (XStream) first stages of the early 2000s could accumulate ice like nobody's business, around the "barrel" of the first stage, but not the "sensing area," as Dive Lab had described it; but it never posed an issue.

Paradoxically, it had been a few of those fellow divers who had purposely "detuned" regulators, to lower IPs for the cold (mine were typically run at a sky-high 12.5 bar; and about 8.5-9 bar for a FFM), who had experienced the majority of the free-flow incidents that I had ever witnessed; but whether that could have just been attributed to mere coincidence, poor pre-dive preparation or some other mechanical issue, I couldn't really say.

I believe that they were using, variously, a "cold-water" Dacor (don't recall the model); a detuned Poseidon Cyklon; and ScubaPro MK2s, for the most part -- whichever had been the most popular model, common to rental fleets, through the late 1980s to the early 1990s . . .

 

[ScubaSteveT]

I’m no expert in cold water diving, but if we’re talking about first stages freezing up wouldn't a lower IP make the situation worse? Greater pressure shift, greater expansion, lower temps created?