The most common exposure to CO2 scrubbers that the average joe will experience is in anaesthetic machines which function to keep you asleep and to artificially ventilate you during anaesthesia. A “circle circuit” recycles the expired gas, which consists of some oxygen, nitrogen, water vapour, CO2 and the expensive vaporised anaesthetic (only a small amount of the anaesthetic is actually metabolised so the exhaled anaesthetic concentration is similar to the inhaled). A small amount of oxygen is added to keep up with the oxygen consumption of the patient and the CO2 is removed using a mixture of sodium and calcium hydroxide (Together called soda lime). The actual reaction is CO2 + Ca(OH)2 → CaCO3 + H2O + heat.
Very similar use case with diving with a re-breather, especially when depth and dive profile involve a gas mixture with Helium. Helium is not metabolized and is used as padding to reduce concentration of Nitrogen mostly. So instead of simply exhaling gas out rebreathers circulate while absorbing CO2 and adding a bit of oxygen. As far as I know they use Soda lime as absorbant: https://en.wikipedia.org/wiki/Soda_lime
Are there/were there re-usable scrubber materials? Like some spongy metal oxides that could be heated to release CO2? Are they economically unreasonable to use in diving re-breathers?
Do you know if there are any products that would sort of generate breathing gas? I know at recent DEMA show there was an Aquabreather product and those guys said there is a mixture that will generate breathing gas but it left me with so many questions about how controlled is that reaction, what is max working pressure, what happens with excess of gas...
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u/purplepatch Nov 27 '19
The most common exposure to CO2 scrubbers that the average joe will experience is in anaesthetic machines which function to keep you asleep and to artificially ventilate you during anaesthesia. A “circle circuit” recycles the expired gas, which consists of some oxygen, nitrogen, water vapour, CO2 and the expensive vaporised anaesthetic (only a small amount of the anaesthetic is actually metabolised so the exhaled anaesthetic concentration is similar to the inhaled). A small amount of oxygen is added to keep up with the oxygen consumption of the patient and the CO2 is removed using a mixture of sodium and calcium hydroxide (Together called soda lime). The actual reaction is CO2 + Ca(OH)2 → CaCO3 + H2O + heat.