Freeze! Freeze?

[Greendiver]

I have a question for all of you who have been on the inside of regulators...

What is it that will freeze when diving in cold water causing a freeflow or OOA incident? Pretty sad to say but I only gave this serious thought after diving this past weekend and recorded temps of 40f-44f.

If you can give me insight on this I would sure appreciate it, thanks!

 

[tfsails]

Obviously you can't dive in freezing water--it'd be ice if it were freezing. However, you can induce the water inside the ambient pressure part of the first stage to freeze in cold water. When the air in the tank leaves the cylinder, it necessarily has to expand. One of the byproducts of air expansion is cooling. If the air expands rapidly enough, it'll cool the water in the ambient part of the first stage enough for ice to form. This ice will restrict movement of the piston or diaphragm (depending on type of first stage), causing it to be unable to close up after you inhale, and you will have a free flow. This freezeup is more likely the colder the water you're diving in.

Cold-water divers routinely use a "sealed" regulator to eliminate freezups. The first stages are sealed to prevent water from getting inside them. Instead, they use either a silicon oil-based medium or a plastic piston behind a watertight seal to transmit depth information to the diaphragm. Sealed piston regs use Christo-Lube as a sealing medium--it's just plain nasty to work with!

Cold-water second stages usually have a lot of metal in them, either the whole case or the breathing tube. Metal transmits heat much better than does plastic. By being metal, they transmit heat from the water (even when it's cold, water has heat in it) to the air in an effort to keep any moisture inside the second stage from freezing.

Hope this helps some.

 

[redacted]

Valves in regulators involve moving parts. As gas passes through a valve, the pressure of that gas drops (the gas expands) and this expanding gas absorbs heat cooling surrounding components. If those components are in contact with water, ice may form. If ice forms on a moving part, the movement may be hindered and the valve may no longer close. And the resultant freeflow will produce more cooling which will produce more ice which will produce more freeflow.

 

[Greendiver]

Thanks for the replies. SO...
IF we have planned properly and have enough air in buddy's tank to breath off of his octo wouldn't it be better to turn the free flow/no flow systems tank valve off to allow the frozen reg to warm to ambient water temp for 1-2 minutes and retry rather than breathing off his system during the ascent/saftey stop? (Still having that as a last resort if still frozen)

 

[gene02]

Why wouldn't you just breath the free flow?

 

[Reallydg]

Thanks for the replies. SO...
IF we have planned properly and have enough air in buddy's tank to breath off of his octo wouldn't it be better to turn the free flow/no flow systems tank valve off to allow the frozen reg to warm to ambient water temp for 1-2 minutes and retry rather than breathing off his system during the ascent/saftey stop? (Still having that as a last resort if still frozen)

Breathing off your buddy's octo "doubles the load" for his/her first stage, increasing the chances of that one freeflowing as well. Add to this, dealing with a freeflow can increase your anxiety, meaning you'll be breathing faster than normal, the demand on your buddy's first stage is going to be pretty heavy. Just my thoughts. I'll let more experienced minds weigh in on what's the better move in this situation.

 

[Greendiver]

Well my initial thinking was that yes breathing off a free flowing regulator is certainly do-able, I would rather make an ascent in cold water breathing from a normally functioning reg, IF possible. Now that said, I really hadn't thought about inducing a freeze in buddies 1st stage by increasing the volume of air/cooling effect in it.

 

[Web Monkey]

Thanks for the replies. SO...
IF we have planned properly and have enough air in buddy's tank to breath off of his octo wouldn't it be better to turn the free flow/no flow systems tank valve off to allow the frozen reg to warm to ambient water temp for 1-2 minutes and retry rather than breathing off his system during the ascent/saftey stop? (Still having that as a last resort if still frozen)

You should do a google search, since this topic was extensively covered here less than a few weeks ago. However the "Cliff's Notes" version is: You can breathe a freeflow for as long as it lasts, which won't be long (anywhere from 0 - 2 minutes or so depending on the reg and how full the tank was and what the flow rate is).

You can also share air with your buddy, but the additional load will probably freeflow his reg too (unless he has a real cold water reg), at which point one OOA diver is now two OOA divers.

The "take away" is that if you plan on diving safely in cold water, you'll need appropriate equipment.

Terry

 

[Greendiver]

Gotcha, I appreciate the info. I'll be sure to search that out. My regulator is environmentally sealed and should be good to go with cold water but I am playing the "what if.." game. Thanks to all!

 

[SwimJim]

Why wouldn't you just breath the free flow?

Down in Georgia your probably diving warm water and if you have a free flow at all it's probably due to a maintenance issue. Up here in the Great lakes when your diving 35 degree water if your first stage goes the air rushing through it will supercool and freeze your gums. That will cost you a trip to the hospital. Not a good thing. That's why your taught to take the second stage out of your mouth and sip the air in the event of a free flow.
Chances are though if you stay below the Mason-Dixon line and or stick to quarries and properly maintain your gear, you won't have an issue. Get out on one of the Great Lakes in an open boat in November, well then, that's another story.

Jim