Originally Posted by
iblondie
How does new oxygen enter the bubble? O_o Wouldn't it just build up with CO2 like when you keep your head under a blanket?
Here you go! This is from their FAQ:
How do you replenish the oxygen content of the air down there?
The quick answer:
The model in the YouTube videos is a manually filled version. We use a standard SCUBA tank which will fill the room about twice. When the air gets thin we empty most of it and then fill it back up with fresh compressed air from a SCUBA tank.
A more in depth answer:
The depletion of oxygen is obviously gradual and the early signs of hypoxia (lack of oxygen) are rather obvious. The first thing you notice is that you feel a little "out of breath". Sometimes you are out of breath if you swam hard to get down, but if it persists then there's not enough oxygen (feels like breathing in a paper bag). Technically the human body can go way beyond that point before it gets dangerous, which is why as soon as anyone "feels it" we refresh. The way we refresh is by letting out 1/2 to 3/4 of the air (huge, amazing bubbles to the surface (there's a clip of that on YouTube)) then re-fill with a SCUBA tank. There's always at least one fresh tank down at the room, and usually a tank with a regulator as well (very helpful for people who have a hard time clearing their ears on the dive down - they can stop halfway and "rest" and work on getting their ears to equalize while breathing off the tank).
One tank will fill it two times or so. The frequency depends on how many people are in the room and how much they are laughing/talking/breathing. Some people use oxygen faster than others. This makes the amount of time the air remains "good" in the room unpredictable, the best sensor we have is the human body. Air is cheap so we always err on the side of caution and re-fresh probably more often than we really need to.
The personal swimming pool model has a "bubbler" that continuously refreshes the air at a rate faster than can be used by the occupants.
Bookmarks