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Tank Valve Freeze Up
- Thread starter nikolaus
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Last serviced over a year ago (believe me, this is one of my lessons learned!). It certainly wasn't free-flowing. Didn't hear/see any leak that severe. Plus, I would not have still had a half tank at 30 minutes into the dive if it had been free-flowing for any length of time.
Oh, and forgot to mention earlier, that after disassembling everything, scooping most of the ice out, letting the rest melt for 15 minutes, and then reassembling, we found that the tank still had about 1300psi in it and everything was working again ... at least on the surface.
I'm thoroughly perplexed....
What happens if a tank has a little water in it and the diver is inverted? Could the water run into the valve or is there something there to prevent this?
Oh, and forgot to mention earlier, that after disassembling everything, scooping most of the ice out, letting the rest melt for 15 minutes, and then reassembling, we found that the tank still had about 1300psi in it and everything was working again ... at least on the surface.
I'm thoroughly perplexed....
What happens if a tank has a little water in it and the diver is inverted? Could the water run into the valve or is there something there to prevent this?
halocline
Contributor
Freezing a tank on land is one thing, because the air around the valve is much less efficient for heat transfer than water. 85F water would prevent freezing way more efficiently than 85F air.
Freezing is usually caused by air expanding in the first stage in the presence of water in the ambient chamber; this freezes the stage open and causes a freeflow. I have never heard of a reg freezing shut; it just doesn't make any sense. In this case, the only guess I would have would be a severe leak at the tank valve o-ring which allowed rapid air expansion and icing between the reg and the valve. The only place water could come from to get in that area would be from the tank. But, if there was still 1300 PSI in the tank, I can't imagine a block of ice holding that back; as soon as it stopped flowing (no air to breathe, no violent freeflow) any ice build up would have melted enough to get it started again. Remember you're in warm salt water which melts ice far more efficiently than air.
So you got out of the water, found there was 1300 PSI in the tank. Why wasn't it flowing like crazy? IOW, when did you turn off the valve?
Freezing is usually caused by air expanding in the first stage in the presence of water in the ambient chamber; this freezes the stage open and causes a freeflow. I have never heard of a reg freezing shut; it just doesn't make any sense. In this case, the only guess I would have would be a severe leak at the tank valve o-ring which allowed rapid air expansion and icing between the reg and the valve. The only place water could come from to get in that area would be from the tank. But, if there was still 1300 PSI in the tank, I can't imagine a block of ice holding that back; as soon as it stopped flowing (no air to breathe, no violent freeflow) any ice build up would have melted enough to get it started again. Remember you're in warm salt water which melts ice far more efficiently than air.
So you got out of the water, found there was 1300 PSI in the tank. Why wasn't it flowing like crazy? IOW, when did you turn off the valve?
This is pretty strange. I know that a regulator or tank valve can freeze. I even know they can freeze in 85 degree salt water. However, the only way for this to possibly happen is for there to be a fairly substantial expansion of air. This air would necessarily have been escaping to ambient pressure. This could only happen with a free flow; and many cubic feet of air would need to flow to create this apparent amount of ice. And, after the free flow stops, the removal of heat would have ended, and a pretty rapid thaw would have begun.
The OP's second statement makes it even more perplexing. It appears that there was enough ice for the OP to get out of the water, disassemble the equipment, and still have ice to "scoop" out of something. And, as he states, after waiting 15 minutes for the remainder of the ice to melt, there was still considerable air in the cylinder. So, where the the volume of expanding air necessary to create this type of freeze originate?
Very strange.
Phil Ellis
www.divesports.com
mikerault
Contributor
If you have ever pulled a valve on a cylinder then you know there is a "dip" tube a couple of inches long on the end of the valve. It is not likely that yo would get that much water in the tank.
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I wonder if those are ever removed or cut down in some cases?
Dip tubes do fall out (and roll around in the cylinder) and are sometimes accidentally left off of the valve during installation, but that would not explain the critical necessity for a large volume of air to be flowing through the regulator just prior to the freeze up. The OP here reports "blocked" ice on the outside of the valve and first stage.
Phil Ellis
www.divesports.com
FredT
Guest
Way back in the dark ages I had a USD reg freeze shut, but it was under thin ice, or I wouldn't still be here. Other than having water in the tank nothing would explain the problem as presented.
Dip tubes do break and/or come off, and the tank in question should definitely have the valve pulled and inspected.
Dip tubes do break and/or come off, and the tank in question should definitely have the valve pulled and inspected.
You guys are all awesome! I really appreciate you all taking time to discuss and respond to my strange question. Even if we can't conclusively figure out what happened, I've learned a lot just reading your responses!
As far as the incident ... There was definitely enough ice to "scoop" out of the tank valve mouth and the opening of the first-stage, but the 15 minute break was just to let any tiny residual or unseen stuff melt and evaporate out. The dive shop guys who witnessed the ice apologized profusely and at length. They kept saying "bad tank", but there was too much of a language barrier to really discuss what they thought had caused it. I know I had a small air leak on earlier dives (buddy reported a regular stream of tiny bubbles escaping) but I really don't think it was ever free-flowing.
As far as the incident ... There was definitely enough ice to "scoop" out of the tank valve mouth and the opening of the first-stage, but the 15 minute break was just to let any tiny residual or unseen stuff melt and evaporate out. The dive shop guys who witnessed the ice apologized profusely and at length. They kept saying "bad tank", but there was too much of a language barrier to really discuss what they thought had caused it. I know I had a small air leak on earlier dives (buddy reported a regular stream of tiny bubbles escaping) but I really don't think it was ever free-flowing.
mikerault
Contributor
With certain types of regulator a small stream of bubbles is expected...it prevents free flows...
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