One of the deeplings shared this SCUBA diving concept called the Triton, a sort of artificial gill that would extract oxygen from the water for you in an on-demand fashion as you swim, obviating the need for bulky SCUBA gear. It’s supposed to work on some sort of nanotube absorption, with a mini battery and compressor to pressurise the oxygen for you. As soon as I saw it, I couldn’t help but think of this:
OK, I hate gearing up for a dive as much as anyone, but unfortunately there’s a bit of physics and physiology that means the Triton concept just ain’t gonna happen. On Earth at least. Naboo, maybe… Let me break it down for you.
- The average human breathes about 500mls of air per breath as their standard tidal volume
- Of that 500 mls, 21% is oxygen going in, and 16% is oxygen coming out, meaning that we strip about 5% of the volume of every breath as pure oxygen, or about 25mls (0.025 liters)
- Using Avagadro’s Law (1 mole of any gas occupies 22.4 liters) we see:
- V1/n1 = V2/n2 –> 22.4L/1mol = 0.025L/Xmol –> X = 0.00111mol. Each breath consumes 0.00111 moles of oxygen gas
- From the molar weight of di-molecular oxygen gas (16g x 2 = 32g/mol), we can calculate that each breath is:
- 32g * 0.00111mol = 0.03552g of oxygen, or 35.52 milligrams (mg)
- Now, well-oxygenated surface ocean waters (on Earth of course, I have no idea about Naboo) contain about 6mg/L of oxygen.
- So, to supply one breath’s worth of oxygen, the Triton would need to filter 35.52mg/6mgL = 5.92L of water. Let’s call it 6L for convenience. And it would need to do so with 100% extraction efficiency, which is not realistic under any diffusion or adsorption scenario, but let’s give Mr Yeon the benefit of the doubt.
- The average person breathes around 15 times per minute at rest. Lets assume we’re diving in a restful fashion, and not chasing Gungans into the underwaterways to escape Colo Clawfish
- Therefore, to supply you with oxygen at normal resting breathing rates, the Triton would need to filter 15 x 6L = 90L per minute, or about 24 gallons. For scale, 25 gallons a minute is about as much as a 1/4 horsepower sump pump pushes out, depending on static head. Without any kind of pump in the Triton to move water through the device, it relies on swimming (and presumably breathe suction?) to create the flow of water. There’s too many variables in that, but let’s just say you’d certainly have to swim so fast to supply the needs of 15bpm that you wouldn’t be breathing 15bpm anymore.
All of this assumes the device is only stripping oxygen from the water, but if you think about it, that wouldn’t work very well. You’ll get your 25mls of pure oxygen, but nothing else. The human mouth holds over 75mls alone (don’t ask how I know this, let’s just say that I learned at college), with at least that much again in the trachea (it was a rough night), so you’re 6 breaths in just to get the gas to your bronchi, let alone the alveoli where the magic happens.
So I’m sorry Jeabyun Yeon, there’s not much future for the Triton. You have an awesome name though. Very Jedi.
EDIT: After publishing, my wife pointed out to me that breathers like this were not only in the Star Wars films, but also in not one but TWO James Bond films: Thunderball and Die Another Day. So, not only is it a fictional concept, it’s also not even an ORIGINAL fictional concept.