Filter (Nitrogen)

The nitrogen filter catches Nitrogen. It fits any gas filter slot, for example in the Filtration. The reserve starts at 100 and drops while filtering.

Nitrogen is a calm gas in the game: not toxic, not a fuel, not an oxidiser. That is why it is the usual filler gas for breathing air. Calculate it like this: a room of four cells needs about 1,330 mol of gas at normal pressure. With 22 % oxygen that is about 293 mol of oxygen and some 1,037 mol of nitrogen. So nitrogen provides the rest of the pressure.

Important for safety: nitrogen does not put out fires in the game and does not make a mixture non-flammable either. All that matters is whether fuel and oxidiser are present.

Where nitrogen comes from:

• Melting ice releases 5 mol per piece, oxite 2.5 mol.
• Nitrice ice gives 22.5 mol of nitrogen, but also 2.5 mol of nitrous oxide. Nitrous oxide is an oxidiser – you need a separate filter for it.
• Many ores release nitrogen when smelted.
• According to the world data, the Venus air holds just under 7 % nitrogen and the Mars air about 3 %.

Nitrogen also works as a cooling gas: it can only turn liquid below 190 K – which can well happen in outdoor lines on Europa (124 to 134 K). At 20.6 J per mole and kelvin, however, it stores less heat than carbon dioxide.

Lifetime: every 145 ticks in which it actually catches nitrogen cost 1 point of reserve – 100 points last a good two hours of continuous use, and liquid nitrogen is caught as well. The medium filter lasts about five times, the heavy one about twenty times as long; all three are made in the Hydraulic Pipe Bender. The catalytic one (about eighty times as long) is only sold by the trader Cosmic Curiosities. More in Gases and mixtures: breathing air, gas mixer, partial pressure.