1st Stage Freeze Up Prevention

[urbanrob]

Norm,
I just dove in Dutch Springs with surface temp of water around 62 and air temp about 74. I went down to about 48 feet when my BC inflator started to free flow. Is this an icing condition from the first stage? I was using an Aqua Lung Titan LX reg/first stage, Oeanic Chute 2 and drysuit. Yes, I took 2-3 breaths topside. Yes, I was adjusting air in the BC and the drysuit on the way down. At 48 feet, temp have been around between 48 and 50. I was decending on a line and the sudden rapid inflation took me by surprise. The BC valve popped as I hung on to dear life. I dumped air several times before I managed to disconnect the inflator hose. Once stable, I waited about a minute and reconnected the hose. It kept on continuous flowing. I pulled it apart again and headed for topside. I reconnected the inflator topside and filled my BC to wade back to shore. This never happened to me before. My dive buddies suggested icing in the first stage but weren't sure. I couldn't replicate the problem topside and figured that I would just swap setups with another reg I had. I never thought that a first stage would freeze in 75 degree weather. Then I read some of the math on this thread. Thoughts/advice/insight regarding the BC inflator and first stage icing?
Thanks,
Urbanrob

 

[WarmWaterDiver]

What was the water content / measured dew point of your gas fill?

Was your first stage fitted with the AL "cold water kit' for the Titan?

 

[jonnythan]

First stage freezeup in 60+ degree water? I doubt it.. more likely an issue with the inflator itself having a nicked O-ring or something..

 

[WarmWaterDiver]

Try calculating the Joule-Thompson effect Jonny - what does the pressurized gas dew point need to be for this to be possible?

Also, read the poster's info that at the depth this occured, the water temp was 48 to 50 degrees F.

Now, why would this be eliminated from the realm of possibility / probability?

 

[jonnythan]

How about you try to imagine what would happen if you disconnected the BC inflator while a first stage freeze-up was causing a runaway BC inflation?

I don't need to pull out my old Thermal and Fluids Engineering textbooks to figure out that if disconnecting the BC inflator solved the problem of a sticking inflator on a hot summer day with water temps over 60 at the surface and over 50 at depth, chances are it wasn't a first stage failure

 

[jonnythan]

BTW, I was at Dutch yesterday as well, and it was a sweltering hot, cloudless day with the sun beating down on everything. The water was over 60 degrees until you got below 30 feet, and though my class didn't go much below 30, it wasn't very cold at depth. My BT and dive logger read temps of over 110 while sitting in the sun, and my tanks went from 2500 to 3000 psi in between dives 1 and 2 (only a 1 hour SI!). The symptoms and situation simply don't indicate a first stage freezeup, don't you agree?

 

[Warren_L]

Try calculating the Joule-Thompson effect Jonny - what does the pressurized gas dew point need to be for this to be possible?

Also, read the poster's info that at the depth this occured, the water temp was 48 to 50 degrees F.

Now, why would this be eliminated from the realm of possibility / probability?

For what it's worth, 50F around here at home is practically the tropics and I would consider a first stage freeze up very improbable, but of course not out of the realm of possibility. Even in waters in the low 30s I've only experienced 2nd stage freezeups. I could maybe believe it might happen if a number of factors at play came together all at once. Perhaps a problem with moisture in the air in the tank, combined with an extremely high draw on the 1st stage (that is not environmentally sealed) all at once for a prolonged period of time. But really, I don't see it happening myself.

 

[urbanrob]

Thanks for all the responses. No, my Titan is not environmentally sealed. But, I thought, like folks here, that the likelihood of a freeze up on such a warm day in such warm water was just short of impossible. After all, I've been in 38 degree water and all was fine.

My local shop said pretty much it wasn't an ice up and he didn't even need to test the reg to tell me it wasn't an overpressure situation. He did a bench test for my piece of mind and it was perfect.

All other evidence points to the inflator (as suggested in this thread). He cited the likelihood as a grain of sand or something snagged the extremely tight clearance on the inflator button cap on the Chute 2 (I do a lot of beach diving). Said that folks sometimes just remove the cap altogether. Recommended that if I leave it on, maybe I'd want to shim the edges a bit to increase the tolerances. Thought it was a good idea.

I checked into recalls and inflator failures on the internet. Apparently, it's not exactly uncommon to have a sticky inflator button (http://www.cdnn.info/recall/recall.html). The Cute 2 didn't appear but its also an older BCD.

In the meantime, I'm also investing in some LP release flanges (http://www.deepseasupply.com/page18.html) to make life that much easier should this happen again. I'll tell you it's kind of tough to otherwise get heavy gloved fingers to pinch the line.

 

[jonnythan]

Good idea... btw if you had a first stage failure that resulted in a freeflowing inflator, disconnecting the inflator, which was acting as the outlet of the extra pressure, would almost certainly result in one or both of your second stages freeflowing instead to vent the pressure. Also, and I'm not sure about this, inflators freeflowing from a first stage freeze-up is rare, as one or both second stages will normally vent the extra gas first.

 

[WarmWaterDiver]

So why did it wait until the diver was at depth, at a lower temperature, to begin Jonny? I'm certainly not berating any theories, but would like to understand the science behind your posts on this event. It didn't appear you had read the post as to what the water temperature was when the event occured, in your post #53 on this thread, as it differed by over 20 degrees F from the poster's data. I'm open to why that was - just let us know.

Is a nicked o-ring often a delayed reaction as described?

And no one specifically asked you to examine textbooks in posts I've seen here - why, one could build a curve / graph from data posted a year or so in this very thread. But, the question was what dew point is required to remove this from the realm of possibility? The old "Once one has eliminated the impossible, the remaining facts, no matter how improbable, must be the truth". So, you've decided already this can't fit in the realm of the 'possible', and I'd like to understand your science.

In your latest post, it appears you may have changed your opinion to 'improbable, but again I see the original poster listing adjusting buoyancy right before the event - let me know why this should be dismissed outright. I'm open to reasoning.

And, once a free-flow is intitated, isn't it self-sustaining if internal icing is the root cause, whether it originates in the first stage or second stage? And if it started free flowing in the inflator, why would the J-T effect of that open path cause the same effect in one of the second stages necessarily? The approach to steady-state would be quite different in the two separate hoses / ports I think.