Ventilation in a flot tank

[wjuniorbr]

Hello

I built an underground room measuring 2,5m x 3m x 2,3 just below the ground, the walls are about 20cm thick in solid concrete, the ceiling has iron structure and semi hollow bricks in the concrete, the whole room is revested in ceramic and porcelain tiles inside, the entrance is a 80cm x 80cm opening on the floor and it´s "sealed" with a wooden door. Its a flotation tank (among other names), its basically a concrete with ceramic tiles tub measuring 2,3m x 1,2m x 40cm. It´s used in sessions of 1 or 2 hours (I was thinking about longer sessions) and it should be isolated from light and sound, but Im afraid of the quantity of O2 and CO2. The room is not perfectly sealed, it has 6 "pipes" in the walls that carries the electrical wires (the pipes are long and they make many curves.
I read somewhere that CO2 from breathing accumulating in the room is more urgent than the lack of oxygen itself, that CO2 is heavier than the air, so does it accumulate from the floor up? Because if it does how should I remove it if it´s already an underground room? I cant use collers because the sessions have to be made in complete silence; I thought about making 1 or 2 holes on the door with pipes making curves inside de door, will this add enought O2 to offset the breathing (by the way the person using is completely relaxed), and will it remove the CO2 since supposedly it´s on the floor because it´s heavier than the O2?
Its in Brazil so the weather is tropical most of the year. The water in the tank is 24 hours heated at about 37 celsius, it has about 700 liters of water with about 400kg of epsom salt (magnesium sulfate). Does this water affect anything in the ventilation matter?

Sorry for the long text, there is no easy way to explain without giving details. Any idea is appreciated.

 

[LittleInch]

When I first read this I thought I might be helping some create a dungeon or room to hide a kidnapped person.... However I read up a bit more and it is a bit more legit. Yes Co2 is an issue and you're right - for CO2 from breathing, the issue is one of toxic concentrations of CO2 rather than lack of O2. Most people refer to this as "stuffiness", but is normally an increased concentration of CO2. You can get devices to measure this and alarm at levels which would be toxic in long exposure or start a fan for short periods.

Because the water should be at body temperature, providing the air outside the chamber is less than this, you should be able to generate some circulation using natural ventilation of warm air rising out of one of your bendy tubes and air coming in via another one providing the end of one tube is say 50cm higher than the other. some vendors recommend that the incoming tube is closest to your head to deliver fresh air to the breathing end.

The room in which this thing is contained needs to have sufficient ventilation to allow the CO2 to dissipate. CO2 does gather at low spots, but this is only usually an issue when you have CO2 concentration at a level where it drives out the O2.

proving you can exit from this tank yourself without outside assistance, you will start to feel the effects of CO2 (being stuffy / lack of air) before you suffer any consequences, but it's hard to see how you can be relaxed and get the benefits of this technique if the air is not pleasant to breathe.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[bimr]

Let's say the average casket measures 84 by 28 by 23 inches, so its total volume is 54.096 cubic inches, or 886 liters. We'll use that as the internal volume too, to give you a few extra minutes of life. And the average volume of a human body is 66 liters. That leaves 820 liters of air, one-fifth of which (164 liters) is oxygen. If a trapped person consumes 0.5 liters of oxygen per minute, it would take almost 5 and a half hours before all the oxygen in the coffin was consumed.


If the typical person consumes 0.5 liters of oxygen per minute; the space is 15,309 liters (after deleting the volumes of .25 m water depth and 66 liter volume of the typical person); assuming the space has 20% oxygen (atmospheric condition); it should take approximately 102 hours before all the oxygen in the coffin was consumed (assuming you started with a ventilated room at the beginning of the period).

One would think it would be a more satisfying experience if the air was clean and odor free. How could it be sensory deprivation, if it is extremely humid and odorous?

https://floatroomsusa.com/floating/

 

[wjuniorbr]

LittleInch - The bent pipes are 3/4" in diameter, do you think it´s enough? and without fans to help the pipes, do you think it will be enough to exchange the air?
bimr - You´re right the O2 will be enough, my main concern is CO2 concentration. After each session a strong fan will be at the door blowing air to the inside for some time, so the sessions will start with fresh air. I havent tried a tank like this yet, because I cant find them in Brazil, but according to my studies the odor is very very weak, and all the studies I ve read say that it´s not 100% sensory deprivation, but it´s enough for the experience. And if this is what science has to offer right now, I ll take it. I´ve seen at least 50 testimonials and all of them say about the same things, not one said anything bad about the experience, they cant all be wrong.

 

[LittleInch]

No - You need something more like 4" for a natural ventilation with as few bends as you can get away with to reduce light coming in.

The O2 is not the issue and in any case anything less than 8-10% oxygen and you die -

http://www.geography.hunter.cuny.edu/tbw/wc.notes/1.atmosphere/oxygen_and_human_requirements.htm

You only need about 2-3% by volume of CO2 to start to become affected by it and anything more than 5-6% over an hour period and you have a 1-5% risk of dying. In the Apollo 13 CO2 issue the levels apparently reached 2% before being rectified and that was recognised as approaching dangerous levels.

If you assume that the oxygen "consumed" turns to CO2 in bimrs figures and you start at 0.03% (normal outside air) and end at 2%, then you end up with about 10 hours.

However if you look up workplace and residential limits though they typically come in at levels starting at 1000 PPM, i.e. 0.1%, when extra ventilation is called for. This reduces your 10 hours down to about half an hour, which sounds about right to me for a box 2m x 3m x 2m even with someone "at rest".

I looked a couple of sites for interest and they all talk about good ventilation of the "pod" being important o the experience, though I'm very happy for someone else to try this myself....


My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[wjuniorbr]

The volume of my room is about 16m³, I was reading that in average the human exhale 325 liters of co2 per day/13,54 per hour. Then a long session of 4 hours would produce 54,16 liters. That´s 3,1% of the air, plus the 0,03 already there, dangerous rate. Is there a way for me to know how much air would the pipes exchange to decrease the 3% rate?

 

[LittleInch]

Difficult to work out a number for air flow as the pressure difference is very very low - some trial and error required, but the bigger the pipe the better. Practicality tells us for natural ventilation you need 4" to 6" to make unforced thermal air flow to occur in sufficient quantities.

your figures are wrong - there's 16,000 litres of air in your "room" - using your CO2 figures (looks like this is a person at rest) you end up with 0.3% (3,000ppm), not 3%. So basically uncomfortable (stuffy), but not dangerous.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[wjuniorbr]

lol, I was just wrong by 10X
So technically safe right? Even if it were sealed?

 

[LittleInch]

Looks that way, but once you start to hyperventilate because you think you're trapped in a concrete tomb you'll breathe out a lot more CO2..... It won't feel very relaxing either if it feels like you're running out of air.

People survive for days trapped in earthquakes, avalanches etc with less space than you have, but I won't be testing this that's for sure...

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[wjuniorbr]

I just bought a CO2 meter, I bought from USA so it will take a while to arrive, but once it does I ll start the testing, untill then I will be having 1 hour sessions which shouldn´t be uncomfortable

 

[LittleInch]

Tell us how it works out and what it feels like. Make sure someone knows you're in it!

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[wjuniorbr]

There are still many thing to do, but here are some pictures of how it is now

http://pt-br.tinypic.com/view.php?pic=123pbnk&s=8#.VFkCMPnF_pc

http://tinypic.com/view.php?pic=scruqw&s=8#.VFkChfnF_pc

http://tinypic.com/view.php?pic=34j9aut&s=8#.VFkD8fnF_pc

http://tinypic.com/view.php?pic=14o1zwi&s=8#.VFkEFfnF_pc

http://tinypic.com/view.php?pic=f9p089&s=8#.VFkEPvnF_pc

 

[LittleInch]

Hmmmm, still looks a bit like the pictures you see when someone is freed after 10 years in captivity, but an hour or so in there sealed off from the world floating in water might be quite relaxing I suppose. Glad you've worked out you won't suffocate, but I would ventilate it well after use.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[wjuniorbr]

According to all the testimonials, it´s something you cant compare to anything else in life out there.
And I guarantee I will not kidnap anybody. LOL