OP
So, if I've let a little water get into the 1st stage (didn't dry the cap or whatever), THAT could cause a freeze???
Tis the season for freeze-flows!
- Thread starter Rick Inman
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True enough but I don't think that's the cause of most free flows. On the other hand there isn't any way to keep the secong stage dry. Besides, if you don't take your dust cap diving with you, you won't get it wet and you won't have to worry about drying it.
I've never had a first stage freeze in the water but I've had 2nd's freeze in an out of the water. Usually once they go they freeflow vigorously until shut off, which, getting to your question, is how you apply heat. Once the reg is freeflowing it will be much colder than the surrounding water. Turning the reg off and waiting for 2 min or so is usually enough to fix the problem. The surrounding water will warm the reg up. So will exhaling through it.
This is the reason you see a lot of cold water divers diving with double regs on H or Y valves. This always gives you the option of turning off a freeflow to deal with the problem under water. Obviously regulators need to be environmentally sealed and fitted with heat-sinks (which can take the form of internal baffles like the Sherwood Maxiumus has).
Having said that I think for every reg I've seen freeze under water I've seen 100 go on the surface and most of those are caused by sloppy entries that set off the octopus.
I dive in nearly freezing water for 4 or 5 months every year and I'll tell you what works for me to avoid freeflows:
1) Limit the time the reg is exposed to wind.
2) don't freeflow the reg to test it. I inhale once to see if everything is working (don't exhale back into the reg - your breath is moist). The less you actuate them the better until you're submerged. BCD function is tested with one short burst and then manually.
3) Turn off the venturi adjustment
4) Once in the water keep the 2nd stages submerged. Put your reg in your mouth just as you are about to descend and EXHALE through the first couple of metres. Never breathe it on the surface once it's wet.
5) and finally (important) when you enter the water make good and sure that your regs don't freeflow. As I previously said I see most regs start to go from sloppy entries. For example if you are making a giant stride into the water hold your thumb over the mouthpiece of your octopus. That's all it takes to avoid the vast majority of freeflows.
R..
I've been fortunate enough not to have experienced any 1st stage free flows, but I've heard this happening to others. Predominantly newer or less experienced divers that perhaps tend to demand more air at depth or do not manage reg use as closely. As well, this would probably happen more with a balanced piston 1st stage like the SP MK25. Which happens to be what I have.
A second stage freeflow can lead to the first stage freezing too. That's the only way I've ever seen it happen. On one occasion I've seen it the diver was unable/unwilling to shutdown and by the time the tank was empty the entire first stage was encased in ice.
R..
That's similar to having poor air usage - drawing too much air all at once increases the cooling effect on the 1st stage and increases the risk of the 1st stage freezing up. A 2nd stage free flow under cold conditions would most certainly cause this to happen.
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