Air

Air

Specific heat	Variable

Description

Air is primarily used to create breathable, pressurized rooms that eliminate the need for EVA suits for humans. It is, however, ill-fitted for use in an EVA suit's oxygen supply, as the nitrogen will not be filtered out of the helmet, which, over time, lowers oxygen concentration in the helmet to unbreathable concentrations. When filling tanks in a nitrox environment, it is advised to use nitrogen filters alongside carbon dioxide filters in the EVA suit to keep the oxygen concentration high in the helmet.

Breathable air is defined in game as a mixture of 75% nitrogen to 25% oxygen.

Breathable atmosphere: composition

For a human player, in order to open or remove the space helmet safely, a room atmosphere with at least 16 kPa oxygen (O2) is safe to breathe and does not generate lung-related warnings. An environment with 16 kPa TO 12 kPA O2 partial pressure will give an OXYGEN LOW warning with yellow lung icon but no damage. An environment with 12 kPa TO 5 kPA O2 partial pressure will give an OXYGEN CRITICAL warning with red lung icon but no damage

Partial pressure can be calculated as: partial pressure = (total absolute pressure) × (volume fraction of gas component). For example in an atmosphere of 65kPA with 35% Oxygen the partial pressure can be calculated as 65 X 0.35 = 22.75 or 22.75 kPA partial pressure of Oxygen.

The presence of other inert gasses (nitrogen, carbon dioxide, water) in the room atmosphere is allowed and not harmful for breathing. It is advisable to add other gasses, to allow plant growth,to increase heat capacity and reduce the risk of ignition.

The presence of some other gas fractions (pollutants, nitrous oxide, volatiles) is harmful for the human player. It will result in warnings in low quantities and damage or loss of consciousness when present in larger quantities.

Breathable atmosphere temperature

Air should be maintained within temperature limits in order to breathe normally as well. If it is too cold or too hot, with open (or without) helmet, it will cause the player to have heavy breathing and/or take lung damage. For a human player the atmosphere should be between 0 and 50°C, if the atmosphere temperature is below 0°C or above 50°C the player will receive a yellow temperature warning, and below -10°C the player will receive a red temperature warning. Below -10°C or above 50°C lung damage will occur.

Comparison to real world

Real-world Earth air comprises 78% Nitrogen, 21% Oxygen, 1% Argon, and 0.04% Carbon Dioxide (up from 0.025% pre-industrial level), plus other trace gasses.

The game allows much more Carbon Dioxide than is typically found in the real-world: anything more that 0.5% CO2 causes headaches, more than 1% CO2 causes cognitive impairment, and more than about 7% causes suffocation (even if there is also sufficient Oxygen).

Gases and Liquids
Elements	Compounds	Mixtures	Other
		Fuel (66.6% H2 + 33.3% O2) Superfuel (50% H2 + 50% N2O) Air (75% N2 + 25% O2)	Atmosphere Coolant