Regulator Freezing

[Marie13]

View attachment 640860

Today would work for a good test of cold water regs.

No need for a boat - just walk out and drill a hole. How's that work with pack ice?

Perfect for @Marie13 ???

My Apeks XTX50/DST got a good workout at the WI mine a few weeks back. 0F air temp but the water was 48F. I had no issues except one first stage froze to the valve when we were done. I knew not to breathe from my regs until I was going under. I’ll be doing my ice diving class in WI the first weekend in March. Today’s weather would be a good test for them ice diving with the surface conditions. -4F air temp and -25F windchill.

 

[lowwall]

View attachment 640860

Today would work for a good test of cold water regs.

No need for a boat - just walk out and drill a hole. How's that work with pack ice?

Perfect for @Marie13 ???

We've got all the ice we need in Chicago right now. Shedd Aquarium is near the top of the shot. Chicago Yacht Club on the bottom right.

 

[M-Cameron]

rather than thinking about this as a pressure conversion, would it make more sense to think of it as an energy conversion?

converting that stored potential energy to kinetic energy.

in essence isnt a 1st stage just a valve?....and isnt lowering the IP in essentially just slowing the speed of the gas leaving the valve?

well if we are slowing the speed of the gas leaving the 1st stage, that gas is going to have a lower kinetic energy..

as we know the higher the kinetic energy, the higher the temperature imparted to that gas......well that energy has to come from somewhere, mainly the stored potential energy of the rest of the gas in the cylinder, and the metal of the first stage, and subsequently the surrounding water...

.....which in theory is why a higher IP results in a higher temperature drop over the 1st stage.

Ide imagine it should be much like taking 2 full cylinders and opening the valve only a crack on one of them....and fully open on the other.

The wide open cylinder is going to output that air at a higher pressure....but will subsequently get much much colder than the partially open cylinder

I'm pretty sure the gas laws, like charles' and gay lussac's law, only applies to closed systems.....and I think that's why they seems to fall apart when applied to an open system like a scuba tank


that was my understanding of it, but admittedly i havent really sat down to look at the math.

 

[shurite7]

...and isnt lowering the IP in essence slowing the speed of the gas leaving the valve?

In my experience with servicing regs and diving in murky cold high elevation lakes, sometimes under the ice while living in MT, first stage ip didn’t have to be lowered. The actual difference in psi/bar isn’t great enough to play a major factor. With that being stated, some older regs benefitted from lowering the ip.

 

[UCFKnightDiver]

rather than thinking about this as a pressure conversion, would it make more sense to think of it as an energy conversion?

converting that stored potential energy to kinetic energy.

in essence isnt a 1st stage just a valve?....and isnt lowering the IP in essentially just slowing the speed of the gas leaving the valve?

well if we are slowing the speed of the gas leaving the 1st stage, that gas is going to have a lower kinetic energy..

as we know the higher the kinetic energy, the higher the temperature imparted to that gas......well that energy has to come from somewhere, mainly the stored potential energy of the rest of the gas in the cylinder, and the metal of the first stage, and subsequently the surrounding water...

.....which in theory is why a higher IP results in a higher temperature drop over the 1st stage.

Ide imagine it should be much like taking 2 full cylinders and opening the valve only a crack on one of them....and fully open on the other.

The wide open cylinder is going to output that air at a higher pressure....but will subsequently get much much colder than the partially open cylinder

I'm pretty sure the gas laws, like charles' and gay lussac's law, only applies to closed systems.....and I think that's why they seems to fall apart when applied to an open system like a scuba tank


that was my understanding of it, but admittedly i havent really sat down to look at the math.

The 1st stage supplies gas on demand based on breathing rate/volume, etc. to "refill" to intermediate pressure. Therefore, you don't really have more flow of gas if you have a higher or lower IP. I don't think you're analogy of two tanks with one valve cracked and the other valve fully open makes sense here because the gas is delivered on demand rather than at a constant rate

 

[Angelo Farina]

If air was a perfect gas, an irreversible adiabatic expansion, not producing any work, such as the lamination process occurring in a valve, would be perfectly isothermal due to the energy conservation principle.
But air is not a perfect gas. So its behaviour deviates from perfect gas laws and you get what is called the Joule-Thomson effect, which is the actual cause of cooling.
See here: Joule–Thomson effect - Wikipedia