A really noob question...

[SteamWake]

Originally Posted by Centred75

Other than the lime absorbant which was usually used only in emergencies (as it was pretty much one time use only, like your brita/pur water filters) submarines of that age just let the CO2 build up in the air (hense the CO2 meter). Subs were designed in such a manner as to allow them to operate submerged long enough that the batteries would run dry before the CO2 levels became dangerous. If situations prevented the sub from surfacing (say they had to sit silent without running engines for over two days) they would crack open the lime to remove the built up CO2.

Run submerged at 2 or 3 knots untill the batteries are flat see which runs out first O2 or the batteries.

The 'air' is refresed very quickly and its easy to miss the notice that has been replenished. Only a brief surface is needed for a gulp of fresh air.