Youtube vid - free flow

[amascuba]

Here is the text by the video.

In light of the unfortunate annual diving fatalities that result from inexperienced divers going too deep too fast, I decided to share a video I shot a couple years ago.

I shot this video while observing an entry level technical dive training class at a midwestern quarry that shall remain nameless. The diver experienced a massive free-flow at 120' while practicing valve shutdowns and regulator switching. He had a few hundred dives under his weight belt and was intimately familiar with the quarry. Even so, watch him struggle to shut down his valves. Ultimately, no one panicked and everyone involved learned a valuable lesson. However, the important thing is that one never knows when something like this will happen. One can take every precaution and accidents still happen, albeit less often.

Cold, dark and deep water plays tricks on the mind. And remember, no one can hear you scream down there...

I disagree that nobody panicked. The student had a brief "oh ****" moment until the instructor stepped in. Also, did anybody notice that the student reached for the instructors 70' regulator?

 

[jjones9527]

Imagine how this would have gone if they didn't have that platform to kneel on. One of the dives on my Tech 1 was a skills dive at 100' doing valve failures, OOA, etc, but we had been beat into us the two days prior in 30-40ft. Here our video Tech One Class on the Munson - Yahoo! Video

 

[rjack321]

With his rather "upright" body position it looked like he was having a hard time before the freeflow.

 

[Flightlead]

That would actually raise the temp (minutely) of the primary, and shouldn't freeze it.

surely because gas would be moving rapidly from the left tank to the right this would chill the left valve. although the gas is not moving through the regulator, some heat would be lost due to conduction.

how would the temp rise? what am I missing?

 

[amascuba]

surely because gas would be moving rapidly from the left tank to the right this would chill the left valve. although the gas is not moving through the regulator, some heat would be lost due to conduction.

how would the temp rise? what am I missing?

friction == heat

 

[Flightlead]

Also, did anybody notice that the student reached for the instructors 70' regulator?

wow, talk about a long hose

 

[amascuba]

wow, talk about a long hose

Should have been more clear. He was reaching for the regulator on the instructors 70' tank. It looked as if the instructor had to rip the regulator out of his hand.

 

[Flightlead]

friction == heat

its an application of the universal gas law. pV=nRT. Since pressure is dropping so does temperature. sure, there may be some friction from the gas passing through, but it is greatly outweighed by the loss of heat energy due to the reduction in pressure.

open one of your tank valves in the garage tonight. after your wife is done yelling at you about all the noise, put your hand on the valve. cold or hot?

 

[ekewaka]

its an application of the universal gas law. pV=nRT. Since pressure is dropping so does temperature. sure, there may be some friction from the gas passing through, but it is greatly outweighed by the loss of heat energy due to the reduction in pressure.

When the isolator is opened, the the pressure is only reduced in the left tank. The pressure on the right is increasing. This will heat the right tank, and cool the left tank
.

 

[ekewaka]

There will not be much effect on the temperature of the regulator because the pressure is always reduced when gas flows through the regulator.