Re: CO2 detector
Yep. It makes sense to have it beep on low battery. It lets you know that you can no longer rely on it.
Except it is a CO (carbon monoxide) not CO2 (carbon dioxide) detector. The difference is important. The atmosphere contains about 0.04% CO2. It comes from animal and plant respiration and from burning stuff with carbon in it (oil, coal, wood, etc.). Concentrations of 1% will make some people sleepy. 7% and up is very dangerous. But, your body will rid itself of excess CO2 very quickly. And, your body can detect CO2. When it builds up in your system, like when you are exercising hard, you start to pant to get rid of it.
CO is a different animal altogether. The natural amount in the atmosphere is only about 0.0000001%. In your house, it can be up to 0.000005%. The maximum safe level is considered to be 0.005%. A concentration of only 0.07% is extremely dangerous, even in the short term. CO attaches to hemoglobin - the molecule in blood that carries oxygen - does not let go and does not let it carry oxygen. If it ties up too much of your hemoglobin, your body cannot get enough oxygen, and you die. Your body cannot readily rid itself of the chemical, nor can it detect it.
CO results from incomplete combustion. Complete combustion gives CO2. Incomplete combustion means that the flame does not have enough oxygen, so the chemical reaction stops part-way through. Pretty much any burning creates some CO, but charcoal burning is a particularly good source of the chemical.
And that is why it is important to have good ventilation when you cook with gas, and to never use a charcoal grill indoors unless it is designed for indoor use.
2009 17' Plan B