Deep thought about Scuba Regulators

[Firebird4life]

I recently thought up of a question that i cant find the answer to. If someone has a "magic" scuba tank that stays at 3000psi always, a "magic" tank that isn't affected by depth or pressure, and "magic" body that can go to any depth (without any consequences of getting the bends or pressure or death AKA invincible), at what depth would a regulator stop working (stop the flow of air). My research so far makes me think that a diaphragm, or piston regulator wouldn't make a difference. I also know that regulators are designed that if their was a major failure in the regulator, that it would open in a constant free flow mode, so is this even possible? Out of everything i have gathered my gut tells me that what would cause the fail is the spring around the load transmitter. I think it might fail due to the water pressure at X depth because the spring wouldn't be able to function. Any thoughts/ideas/comments???


Thanks

 

[IanBrit]

As soon as the ambient pressure matched the pressure in the tank, minus a chunk that's needed to overcome the resistance of the mechanism (including spring, frictional losses and a few other aspects). For the ambient pressure to be in the region of 3000 psi, you'd have to be in roughly 6700 feet of sea water.

 

[t.pickett66]

There is a nice visualization of this over @xkcd, although it refers to what would happen if you put a hole in the tank but the depth would be about the same.

 

[Firebird4life]

so is 6,700 feet the depth that a regulator would fail?? that dosnet seem right...

 

[nimoh]

Luckily I have HP tanks for my dives down to the bottom of Lake Baikal

Seriously though, interesting thought, with a surprisingly simple answer. I admit I didn't put much thought into it (hence my surprise), but makes perfect sense--3000psi pushing in, 3000psi pushing out and the air goes nowhere.

 

[Tigerman]

so is 6,700 feet the depth that a regulator would fail?? that dosnet seem right...

The regulator will fail to provide breathing gas when the water excert as many PSI of pressure as the pressure inside your tank.
In other words, dependant on tank pressure.

 

[IanBrit]

The math behind it... 3000 psi = 3000/14.7 = 204 atmospheres.

204 atmospheres occurs at (204-1) * 33 = 6701 feet of sea water.

I'm guessing the reg would have given up a little earlier due to mechanical stress of trying to deliver sufficient air to this invincible diver's lungs. That, and the part that while the diver may be narc immune, that magic tank had better be delivering some magic PPO2 controls too

 

[Tigerman]

Excluding the part where you get crushed to death, narced to death and o2-toxed to death, such theoretical thought experiments is fun though.
But in reality, the reg and tank will never stop delivering air due to depth, but rather because you dont watch the gauges or mechanical error.

It would probably freeflow because the purge get pushed in by pressure long before you get to 6700 feet below the surface too..

 

[IanBrit]

But in reality, the reg and tank will never stop delivering air due to depth, but rather because you dont watch the gauges or mechanical error.
I

I guess it depends in this thought experiment by what you mean of 'never stop delivering' - once pressures equalize, 'delivery' will be reduced to diffusion.

 

[PfcAJ]

Excluding the part where you get crushed to death, narced to death and o2-toxed to death, such theoretical thought experiments is fun though.
But in reality, the reg and tank will never stop delivering air due to depth, but rather because you dont watch the gauges or mechanical error.

It would probably freeflow because the purge get pushed in by pressure long before you get to 6700 feet below the surface too..

Thats not how regs work...