Hi, i am new to ARDUINO, i was lookig for a circuit to controll an scrubber on ebay , with no succes, the start to find ARDUINO BAROMETRIC PRESSURE SENSOR and CARBON MONOXIDE GAS SENSOR for ARDUINO UNO
Is how i came to the forum
My project is simple in concep, a barometric pressure sensor will maintan the cabin pressure at 1 atm, as is an enclosed hermetic cabin the CO2 build up will occour and oxigen depletion, so the board will activate an 12v valve to let enter oxigen and another to relase pressure, this to maintain the pressure and CO2 on preset limits, i draw a block diagram to build it with microchip pic, but as the sensors are avaliable for the arduino uno, all looks in place but after read the arduino uno board, not have analog outputs, how i can use it? will apreciate any option to experiment with this boards, the circuit will be used on an small 1 atm submersible.
robertalv:
so the board will activate an 12v valve to let enter oxigen and another to relase pressure, this to maintain the pressure and CO2 on preset limits
One problem I see is that as you pump out air and let in oxygen the partial pressure of oxygen will go up because 70% of what you are pumping out is nitrogen and 0% of what you are letting in is nitrogen. This will cause health problems and a fire hazard. You want to keep the "partial pressure" of oxygen constant. As the proportion of oxygen goes up the atmospheric pressure has to go down.
You might want three Arduino's with three separately written programs and make sure that at least two agree before actuating any valves.
I am assuming you are talking about scuba tanks using standard compressed air mixture.
The issue you will get is not low oxygen, but build up of CO2. Space craft, submarines, closed circuit breathing systems, etc all have to worry about that. That is why they have CO2 scrubbers in them.
I am absolutely no expert, but I believe CO2 poisoning makes you dumb, unable to make good decisions. F-22 fighters suffered from an issue with it not to long ago and I believe one pilot was killed due to it.
I believe most people who build submersibles as amatures get their air from the surface instead of an actual sealed system due to the complexity of keeping the build up of toxic gas to a minimum.
Realize, you are taking your life in your hands if you continue with this project along the lines you are going. The very real possibility of you dying while submersed exists and is very close based on your current idea and understanding of what you are doing.
At the very least, talk to a highly qualified scuba diver who is familiar with diving. They will probably tell you this is a horrible idea.
In the OP, he mentions scrubbers, so he is taking care of the CO2.
The problem is not buildup of CO2, in one sense. The body is acutely aware of the build up of CO2, because you start to feel like you are suffocating. As long as whoever is in the chamber can do something about it, they can handle build up of CO2. (Of course, if they can't do anything about it, it would be an awful way to die.)
The problem is the lack of O2 without a buildup of CO2. The body has no warning about this, and you just keel over and die, with no forewarning.
The best illustration of this was an episode of an old TV show called "The Body in Question" by Dr. Jonathon Miller. He first set up a system where he was breathing his own air. After a few minutes he quickly pulled off the mask because he was suffocating. The second time he breathed his own air with a scrubber that removed the CO2. He calmly kept talking and writing on a pad, though his writing became more and more illegible. He finally passed out and his assistants rushed in with oxygen.
Would this be similar to a rebreather,
Hi,
Atmel products are not suitable for, and shall not be used in, automotive applications. Atmel products are not intended, authorized, or warranted for use as components in applications intended
to support or sustain life.
find this at the bottom of most Atmel data and application sheets, very small print.
Tom..... 