Do regulator heatsinks actually increase regulator freezing during ice diving?

[tbone1004]

@tbone1004 I think there's a misunderstanding here about the Norsok test. Although this test is performed in cold water down to 400msw, it uses Heliox. Heliox does not freeze your first stage but heats it. Apeks were tested to 200msw on Heliox. This test is only interesting for work of breathing at depth for example for deep professional divers on heliox, but it does not tell much about freezing issues for recreational divers on air or trimix.

please explain how heliox becomes exothermic when it loses pressure, but nitrogen magically makes it endothermic.
I'm well aware of what that test does and it still tells quite a bit about how it's going to freeze for recreational divers. It can't pass the test of it freezes, and no, heliox isn't exothermic.

@Joebar the concern is moreso inside of the second stage housing for a reg to freeze than the first stage. The second stages have fresh water condensing on them from your exhalation breath and that tends to cause more problems than ambient water

 

[Joebar]

my fault.

what is the freezing temp. of seawater? 30F? According to the graphs you only cool the regulator when your tank is near empty (500psi)

 

[Joris Vd]

please explain how heliox becomes exothermic when it loses pressure, but nitrogen magically makes it endothermic.
I'm well aware of what that test does and it still tells quite a bit about how it's going to freeze for recreational divers. It can't pass the test of it freezes, and no, heliox isn't exothermic.

@Joebar the concern is moreso inside of the second stage housing for a reg to freeze than the first stage. The second stages have fresh water condensing on them from your exhalation breath and that tends to cause more problems than ambient water

Isn't the main problem actually that compressor filters are not being changed often enough making the air contain too much moisture? Which means the temp drop from the gas flow can form ice crystal inside the first stage / second stage which usually manifests in the poppet not closing properly at the second stage lever?

 

[tbone1004]

Isn't the main problem actually that compressor filters are not being changed often enough making the air contain too much moisture? Which means the temp drop from the gas flow can form ice crystal inside the first stage / second stage which usually manifests in the poppet not closing properly at the second stage lever?

it can be one of the problems, but most of what I have seen is the second stages freezing due to moisture being rapidly chilled from the gas coming out. I haven't seen a reg freeze internally yet, granted I work with compressors that actually have their PM done properly

 

[leadduck]

please explain how heliox becomes exothermic when it loses pressure, but nitrogen magically makes it endothermic.
I'm well aware of what that test does and it still tells quite a bit about how it's going to freeze for recreational divers. It can't pass the test of it freezes, and no, heliox isn't exothermic.

Please look up the Joule Thompson effect in Wikipedia, particularly how it differs for air (both oxygen and nitrogen cool down when expanding in the first stage) and helium (heats up when expanding in the first stage). Freezing first stages is not an issue with high percentage helium mixes.

 

[tbone1004]

Please look up the Joule Thompson effect in Wikipedia, particularly how it differs for air (both oxygen and nitrogen cool down when expanding in the first stage) and helium (heats up when expanding in the first stage). Freezing first stages is not an issue with high percentage helium mixes.

that's a 200m dive on heliox *albeit simulated during the Norsok testing in a chamber*, rich heliox so 5/95 or less due to the depth. That looks like an ice block to me. Not a problem, just a block of ice.

We are outside the inversion temp for He sure, but is it enough to offset the cooling of O2?
I'm not going to do the math since I'm working and also not a chemist, but since the specific heat of the two gases are radically different, I'm going to guess that while He may warm up a touch when it goes through the valve, it's more than offset by the O2 with or without the N2.

We are also outside my area of expertise since I'm not a chemist, but I am part of an SBIR right now for the USN who is wanting active heating of heliox due to the cooling, and anecdotally, I've seen a lot of heliox regs come back with ice blocks on them and have seen more than a few pure helium tank valves freeze up when draining tanks. I also know that when I mix helium the valves and regs are not warmer than ambient. Not as cold as O2/He, but they definitely aren't warm.

 

[leadduck]

This is an image from a presentation on measurements inside a first stage at 50m, 4°C water temp. Left side: air, right side: trimix with 58% helium. You can see nicely how the same reg with air easily reaches -20°C, whereas with 58% helium it never goes below +2°C and warms up to +4°C when breathing starts. The specific heat capacity of helium is much higher than of air, hence just calculating a weighted sum of inversion temperatures won't work.
Heliox usually gets heated for the working saturation divers because else the diver loses so much heat.

 

[tbone1004]

@leadduck well no sh!t, that's surprising. I know they heat the umbilical air, but it still doesn't explain how and why the first stages are icing over on the machines during testing.

 

[Storker]

Apex

<nitpick>
Apeks
</nitpick>

Please look up the Joule Thompson effect in Wikipedia, particularly how it differs for air (both oxygen and nitrogen cool down when expanding in the first stage) and helium (heats up when expanding in the first stage).

Cool. I learned something today. Wasn't aware that some fluids (H2, He and Ne, but not many others) actually increase their temperature on adiabatic expansion at "normal" temperatures.

Heliox usually gets heated for the working saturation divers because else the diver loses so much heat.

Well, AFAIU that has to do with heat capacities and heat transfer coefficients, not with Joule-Thomson coefficients...

 

[Schwob]

View attachment 473424

This is an image from a presentation on measurements inside a first stage at 50m, 4°C water temp. Left side: air, right side: trimix with 58% helium. You can see nicely how the same reg with air easily reaches -20°C, whereas with 58% helium it never goes below +2°C and warms up to +4°C when breathing starts. The specific heat capacity of helium is much higher than of air, hence just calculating a weighted sum of inversion temperatures won't work.
Heliox usually gets heated for the working saturation divers because else the diver loses so much heat.

Say, might there be a place where one could read or download the whole presentation (in German is just fine)? Interesting.