User talk:Rethkir

Rocketry info

I've added my notes on decompiled rocket engine code on User:RA2lover/Sandbox/Thermodynamics_machinery_notes. I refuse to post on reddit since getting disgusted by its API changes and i'm not on discord since getting banned from it, but still occasionally check /r/stationeers. saw your post there and figured maybe some info may be useful.

Is the PFGE max thrust figure obtained from running both inputs with premixed 60.7MPa fuel at 196 K? You can add up to 0.05 mol/L of frozen gases or liquids to a pipe network before it starts taking damage and i wonder if adding ~0.134% of frozen liquid nitrous oxide is enough to get another 100-200N of thrust. RA2lover (talk) 03:18, 21 January 2026 (CST)

Evaporation coefficients

Saw your reddit post asking for these so i went looking for them. The game does, in fact, use exponential curves for these and they can be found in the MoleHelper class as EvaporationCoefficientA And EvaporationCoefficientB.

The evaporation pressure for a given temperature and liquid is EvaporationCoefficientA * Temperature^EvaporationCoefficientB
The evaporation temperature for a given pressure and liquid is ( Pressure / EvaporationCoefficientA )^( 1 / EvaporationCoefficientB )

Here are the coefficients for each liquid:

 Liquid              A                    B
 Oxygen              2.6854996004e-11     6.49214937325
 Nitrogen            5.5757107833e-7      4.40221368946
 Carbon Dioxide      1.579573e-26         12.195837931
 Volatiles           5.863496734e-15      7.8643601035
 Pollutant           2.079033884          1.31202194555
 Water               3.8782059839e-19     7.90030107708
 Polluted Water      4e-20                8.27025711260823
 Nitrous Oxide       0.065353501531       1.70297431874
 Hydrogen            3.18041E-05          4.4843872973

Steam uses the same coefficients as water. RA2lover (talk) 14:39, 22 January 2026 (CST)

Also, note frozen liquids linearly interpolate their evaporation pressures from their freezing point values at their freezing temperature down to 6.3 kPa at half their freezing temperature, see [1]. I'm not sure if there's an application where this is useful(open-cycle pollutant evaporation chamber for liquid oxygen?), but it's there. 15:22, 22 January 2026 (CST)

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Hey, thanks for taking the time to write to me. I appreciate this info very much.

"Is the PFGE max thrust figure obtained from running both inputs with premixed 60.7MPa fuel at 196 K?"

Yes, that is exactly what I did with Volatile/O2 mix. I didn't try testing it with N2O mix since it seemed convoluted, so I didn't update that value. Though at this point I have a better understanding of how to get it to work, so I might just test that for the sake of getting it on record.

"You can add up to 0.05 mol/L of frozen gases or liquids to a pipe network before it starts taking damage and i wonder if adding ~0.134% of frozen liquid nitrous oxide is enough to get another 100-200N of thrust."

Oh, that's very neat. I didn't know about this limit. So it would be a fuel mix with a tiny superfuel boost. Not practical, but kinda cool. I'll probably try it out before building an N2O PFGE.

And thanks for the coefficients. I saw someone posted them on Reddit, but this list is more comprehensive. I noticed that the 6.3 kPA min and 6000 kPA max defines the minimum and maximum liquid temperatures for some substances, but not others like CO2, N2O, and pollutants. Are those limits defined by the wiki values, or is there something more going on?

"Also, note frozen liquids linearly interpolate their evaporation pressures from their freezing point values at their freezing temperature down to 6.3 kPa at half their freezing temperature, see [1]. I'm not sure if there's an application where this is useful(open-cycle pollutant evaporation chamber for liquid oxygen?), but it's there"

Huh, so the phase change diagrams showing a vertical line aren't exactly accurate, then? Technically it should be a slope? Weird. -Rethkir (talk) 22:36, 22 January 2026 (CST)

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I think the superfuel additive might be more practical than not. The only other use for it at the stage you can afford to mix rocket-sized quantities of it is trading and there's enough tolerance for impurities that it should be able to sneak by. You'd lose the autoignition safety margin though so using it in a welder probably wouldn't be a good idea. Would be a fun way to get traders to rotate faster if that were ever implemented xD
nvm landing pad gas pumps only transfer gases -RA2lover (talk)

Minimum/Maximum liquid pressures are defined on Mole:MinLiquidPressure and Mole:MinimumLiquidPressureAtMaxTemperature (which match the reported wiki values) and are the actual methods used to populate stationpedia entries).
Minimum/Maximum temperatures are defined on Mole:FreezingTemperature and Mole:MaxLiquidTemperature, which *should* be accurate to the current wiki values but i haven't checked myself (and are rounded on stationpedia):

 Substance        FreezingTemperature(K)    MaxLiquidTemperature(K)   Liquid Molar Volume(L/mol)
 Oxygen           56.416                    162.2                     0.03                        
 Nitrogen         40.01                     190                       0.0348
 Carbon Dioxide   217.82                    265                       0.04
 Volatiles        81.6                      195                       0.04
 Pollutant        173.32                    425                       0.04
 Water            273.15                    643                       0.018
 Nitrous Oxide    252.1                     430.6                     0.026
 Hydrogen         16                        70                        0.03
 Polluted Water   276.15                    629                       0.018

I haven't checked if these match with their corresponding values at the evaporation temperature/pressure curves or are all present on the wiki pages. The in-world liquid volume multiplier is most likely not as it's actually calculated at runtime instead of stored ingame (MoleHelper:CacheInWorldVolumeMultipliers, which internally uses MoleHelper:CalculateInWorldVolumeMultiplier).
It basically gets the amount of gas at Minimum liquid pressure at max temperature for a world grid cell(8000L), then makes it so that quantity equals 7990L of in-world liquid (i'm too lazy to calculate it manually). End result should be that a room full of liquid should boil to a gas with a negligible change in pressure.

As for the phase change diagrams on the stationpedia - their charts are calculated on UI.PhaseChange.PhaseChangeDiagram:CalculateY, which forces the y position to 6.3 kPa if plotting below the freezing point and to max_double if above the max liquid temperature.
I don't have an idea on how to chart these, though - while the evaporation pressure keeps decreasing, the condensation pressure does not(and would stay at a horizontal line at the minimum liquid pressure, down to 0 K).
No evaporation will happen, regardless of pressure, below half the freezing point (though gas can still be condensed).
Fixing the diagram would need 2 lines: a condensation pressure (staying horizontal at 1800 kPa for pollutant below the freezing point), and an evaporation pressure(which would decrease linearly to 6.3 kPa at 86.66 K before vanishing?). The log scale diagram option distorts the chart into a log10 scale, so the separation between that and the exponential part would be difficult to see because the derivatives of the curves are at the same order of magnitude. You might have more success distinguishing it on carbon dioxide. -RA2lover (talk) 01:32, 23 January 2026 (CST)