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John: I agree that second stage freeze ups are the norm. However although rare first stage freezing is possible. The most common way is for moisture to be in the 1st stage as was the case with Steve. My concern was how the moisture got there.I've included a snip of a message from Steve which details his problem as he now understands it. "The DM's there will dissasemble your gear if you don't stop them. They use the disproven method of "blowing out" the reg. I think that's where I picked up the water. They also fill 200 + tanks a day, so I think their air had a high dew point. They had a 75 CFM Bauer, it was the biggest scuba compressor I've ever seen. The thing was mounted on a two axel, 4000 lb trailer, and it ran all day. I don't think they changed the filters every day. I think the ice formed in the first stage, and inhibted the movement of the piston. This caused the IP to be too low, and the ballon that acts as the second stage valve seat never fully inflated. I think the IP was too low for the correct pnumatic balance to occur. Rmemeber, the failure happened when I first pressurized the reg at 10F, and it cleared when they dumped hot water on the first stage, not the second." I now feel that the small amount of moisture left in the reg from his "cozumel blowing out" procedure or high dew point from their compresser, is very possible as the reg seems to have been frozen before being pressurized. My original understanding was that the reg faied while in use, and I felt that the residual moisture would have been blowen through and was concerned about more moisture being injected. Ian you wrote >Personally,after 10 years of michigan diving,I NEVER saw a first-stage >freezup in ANY brand of reg.2nd stage freezes are more common,but still not >a very common occurrence. > Most of the fixes/precautions have been discussed here,including clean >regs & not breathing from the 2nd stage out of the water.My guess would be >these both prevent the formation of "seed crystal",or sites where >crystallization (i.e. freezing) can begin.We used to perform all our reg >checks just below the surface before proceeding with the dive.This helps >prevent freezups due to testing on the surface,but can result in some >frustration since you then have to climb out of the freezing water to change >regs (trying to unthaw it at the site usually doesnt work). > Finally,is everyone aware that a regulator freezup almost always results >in a free-flow,rather than a shutting-off of the air supply?Granted,this is >still not a desirable situation,but nowhere near as immediate a problem as a >totally non-functional reg (i.e.,one that provides NO air).You CAN shut off >the offending 2nd stage,and either breathe from the backup,or control the >airflow with the tank valve long enough to get to the surface.That's for >survival,however,not a way to continue a dive that should be aborted. > We had good luck with both the posiedon and the older version of the >scubapro g250( the 109).The worst respones came from old,dirty,or cheap regs. > John L. Dunk o > Tallhassee,Fl. o > screwloose@ne*.co* ______o_________ > > >
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