Conditions for a First Stage freeze?

[Bretagus]

Hi - So I did my first sub-40F dive today (39, but hey, that counts!) Anyway, I was massively impressed with my old Sherwood Brut in its ability to do its job and not freeze. My understanding is freeze ups can happen <45F and it is exascerbated by heavy breathing. Since my unsealed, unbalanced, former rental-reg didn't die on me... this got me wondering... under what conditions have you had a reg freeze up?

I'll obviously remain wary, given that my equipment was not designed for this type of use, and given I've only had 60-70 minutes of testing... but still... go Brut!

 

[cbmech2]

Something that you may find interesting is a test report from the good folks at the Navy Experimental Dive Unit (NEDU). They do quite a bit of testing to qualify scuba equipment to be on their authorized use list and I do remember seeing such tests being documented. I stumbled upon it by searching via Google.

 

[elan]

Hi - So I did my first sub-40F dive today (39, but hey, that counts!) Anyway, I was massively impressed with my old Sherwood Brut in its ability to do its job and not freeze. My understanding is freeze ups can happen <45F and it is exascerbated by heavy breathing. Since my unsealed, unbalanced, former rental-reg didn't die on me... this got me wondering... under what conditions have you had a reg freeze up?

I'll obviously remain wary, given that my equipment was not designed for this type of use, and given I've only had 60-70 minutes of testing... but still... go Brut!

I had only 2 dives on my Zeagle Flathead which is sealed in cold water (36F) and it did not freeze Well it sealed. When I was preparing for my dives I was doing some research and read some books intended for Ice Diving Rescue. The factors that will contribute freezing that I have found are the following:
- if the reg is submerged and then taken out and the air is < 0 it can freeze , even sealed regs can freeze of moisture got inside (when switching tanks for example, or the air in the tank has some moisture) Thus when you submerged you stay submerged (this recommendation is for the second stage and the unsealed 1 st.)
- high breathing rates (in the cold water it is recommended to inhale slow)
- using octo is very undesirable as when you body starts breathing out of your octo the rate can increase as much as 10 times in the stress situation. This will cool the 1 st stage quickly and can cause the freeflow


I would personally avoid using unsealed 1 st stages as this is gambling and just reduces your safety margin. Besides our instructor said never use piston first stage for ice diving. I cannot comment on that as I'm not that advanced yet.

And I also used a pony bottle as an alternative source when diving cold.

 

[eponym]

under what conditions have you had a reg freeze up?

When the air is cold, breathing off the reg or using the BC inflator (on the surface) can cool the first stage to the point where it will freeze up once in the water. So your gear assembly/testing needs to be different in cold weather. Don't take more than a sip of air on the second stages, if you must. Keep the first stage out of the wind--put a heavy sock or a watch cap over it if it's going to sit out on the tank for a spell before you get in. Inflate your BC orally to start. Once you're under the surface the water will transfer enough heat to the first stage (even 39-degree water has heat) to keep it from freezing, as long as you're not breathing hard or leaning on a BC or drysuit inflate button. Short bursts with long pauses between them is ideal. I've also seen freeze-ups start underwater during reg retrieval drills, because of overuse of the purge valve.

Turning off the air for a couple of minutes is usually enough to allow the first stage to thaw underwater. Of course, breathing hard off your buddy's tank now puts that reg in danger of freeze-up, so sometimes ascending while sipping from the free-flow is the way to go.

There have been some good threads on this over the years. Search on "freeze" and you'll see lots to read.

-Bryan

 

[NorthWoodsDiver]

I had my scubapro mk25/S600 freeze on a dive in the spring in minnesota. I dont remember off hand what the exact water temp was but since they never get warmer than 41 degrees in the summer it was probably in the 37-39 degree range. I did a dive to 131 ft and had the reg pop off at around 90 ft on the way back up. I probably over breathed it without knowing as I was still fairly fresh to diving especially in cold water at that time. I feathered the valve until I got into the thermocline.

I dont dive mk25's anymore and stick with the mk17/S600 and have not had an issue since.

 

[Maximum Overdive]

I'm a fairly green diver and thought I'ld go with the dive club this year for the new years dive, well the first stage became a ball of ice and free flowed on the surface before I even got under. I was able to borrow another set of regs from a diver that decided it was too cold for him and made it under 14 feet before my buddy free flowed and we had to cancel the dive. Temp. was 32 degrees. I see here by your post that I did just about everything wrong, hopefully next year the new years dive will be a little longer and more enjoyable. Thanx for the lesson!

 

[eponym]

Max, good post, nice image ("ball of ice").

Since we often have cold-air cold-water conditions here in the winter (but not as bad as Ontario, I'd guess), I've started talking about this subject in open water diver courses, for the few hardy souls who will actually want to dive locally in the winter.

-Bryan