Stationeers Gas Mixer Calculator
The exact Gas Mixer percentage for a clean volatiles and oxygen burn when your two lines are at different temperatures, plus the ideal-gas conversions an IC10 script needs. All arithmetic, in your browser.
1. Fuel mix ratio
Set both temperatures in Kelvin. The result is the percentage to dial into the Gas Mixer's volatiles side.
2. Ideal gas law
Leave one field blank, or pick what to solve for. Pressure in kPa, volume in litres, temperature in Kelvin, R = 8.314.
3. Moles to hit a target pressure
What an IC10 script compares against a tank's Moles reading
before it decides to keep pumping. Splits the total by your mix ratio from panel 1.
Want this on a real server? Supercraft hosts Stationeers →
Where the mix formula comes from
Complete combustion of volatiles takes two parts volatiles to one part oxygen, by moles. The Gas Mixer, though, divides by volume. Start from the ideal gas law for the two streams at a common pressure:
n = PV / (RT), so n_volatiles / n_oxygen = (V_vol / T_vol) / (V_oxy / T_oxy)
Set that equal to 2 and rearrange, and the volumes must satisfy
V_vol / V_oxy = 2 x T_vol / T_oxy. Expressed as the percentage the mixer actually
wants:
MixRatio % = 100 / (1 + T_oxygen / (2 x T_volatiles))
At equal temperatures that collapses to 66.67%, exactly as expected. Feed 200 K volatiles against 300 K oxygen and it moves to 57.14%; reverse them and it goes to 75%. That drift is the reason a mix that behaved yesterday burns dirty today after you changed a cooling loop.
The usual advice on the forums is to put a heat exchanger between the two lines and let them equalise, which works precisely because it makes the temperature term cancel. If you would rather not build one, the formula above is the alternative.
Atmospherics is the part of Stationeers that most rewards a server that never stops simulating: pressures settle, furnaces hold temperature and a filtration loop keeps working while nobody is logged in. That is what a hosted Stationeers server is for.
FAQ
Is the Gas Mixer ratio by volume or by moles?
By volume, which is the crux of the whole problem. Two streams at the same pressure but different temperatures do not carry the same moles per litre, so an even volumetric split is not an even molar split. Everything on this page is the conversion between the two.
What percentage should I use for a fuel mix?
66.67% volatiles when both inputs share a temperature. Use panel 1 when they do not.
Why is my burn dirty even though the dial says 66?
Check the two input temperatures before anything else. Cold oxygen against warm volatiles makes the real molar mix oxygen-rich, which burns hotter and leaves unburnt gas behind.
How do I use this with an IC10 script?
Panel 3 gives the total moles for a target pressure and splits them by your ratio. A typical
script reads a tank's Moles and drives a volume pump until it reaches that
figure, which is more reliable than pumping to a pressure while the temperature is still
moving.
Does any of this leave my browser?
No. There is no upload, no account and no server call - it is arithmetic on the numbers you type.