Gas Mixers giving incorrect output

[mahashma]

I'm feeding a gas mixer H2 and O2, with both lines pressurized to 3MPa and temperature controlled at 100C. But instead of a 67/33 mix I'm getting something that's more 72/28. What would be causing this? Any ideas?

*edit to add yes, the correct inputs are being used and the mixer is set to a (nominal) 67/33

[Torn4dO]

Are you sure both gasses are EXACTLY the same temperature?
I would recommend a IC to control the setting of the gas mixer, that way it doesn't matter what the temperatures are.

alias H2tank d0 #PipeAnalyser/Tank for input pipe 1 
alias O2tank d1 #PipeAnalyser/Tank for input pipe 2 
alias mixer d2 
define ratio 2 # ratio input1 to input2 

start: 
yield 
l r0 H2tank Temperature 
l r1 O2tank Temperature 
mul r0 r0 ratio 
add r1 r1 r0 
div r0 r0 r1 
mul r0 r0 100 
s mixer Setting r0 
j start

[God, owner of the Universe]

Personally, I never use the Gas Mixer, instead I use 2 volume pumps (IC10 controlled).

EDIT (after 5 more comments): For those who want to see the Gas Mixer temperature problem in action, or how to instead do it with Volume Pumps and programming, here's a 10 minute video:

https://www.youtube.com/watch?v=ySsiHZR4aug

[JeanDeaux]

I do like using the gas mixer, but as Tornado pointed out you have to also manage the temperatures between the gases else your final mix will be off. I like sending the gasses through a heat exchanger first to equalize the temperatures just prior to using the mixer.

Good luck.

[mb08]

I dont have any problems with the mixer. I simply use heat exchangers to equalize the gas temperatures. And it does not matter which inputr pressure the gasses have. I always have a fine fuel mix. I am playing at Europa.

[WussyBoy]

If you are feeding a 2:1 ratio from 3Mpa pipes, eventually the input pressure of the H2 will fall faster than the O2 and the ratio will change. The less volume in the in-feed, the faster the ratios will get out of whack. This happens even if the temperatures are identical.

Perhaps try using a pressure regulator in front of each of the gas inputs to the mixer with an optional buffer (small inline gas tank) as well, thus limiting the input lines to a specific pressure like 1 Mpa. Maybe you are already doing that, but it doesn't specifically mention it so I thought I'd add the tip. I have never had an issue with mixture ratios as long as the input pressures and temperatures were identical (or nearly so).

If you do use two pressure regulators set to 1 Mpa, the output of both will stay steady until the feeding tank pressure drops below that threshold.

Feed tanks @ >1Mpa ---> pressure regulators set to 1 Mpa ---> optional buffer ---> mixer

I'm working towards more automation since diving into IC10 programming which is fun, but there is a certain charm in understanding the manual control assembly too.

[lisnaz]

I've written one that mix gases at whatever temperature, change to your needs.

It's an implementation of the https://stationeers-wiki.com/Pipe_Gas_Mixer#Precision_gas_mixing, please reference that for the meaning of variables in the code.

define SGM HASH("StructureGasMixer")
define SPA HASH("StructurePipeAnalysizer")
define SLTBI HASH("StructureLiquidTankBigInsulated")
define STBI HASH("StructureTankBigInsulated")
define FuelTank HASH("Fuel Tank")
define VolTank HASH("Vol Tank")
define O2Tank HASH("O2 Tank")
define AfterMixPA HASH("Fuel After Mix PA")
define FuelGasMixer HASH("Fuel Gas Mixer")

define MinimumVolMoles 2000
define MinimumO2Moles 1000
define MaximumFuelMoles 20000
define FuelTargetRatio 0.666666 # Vol:O2
define ReverseMixerInput 0

alias totalOutputVolume r15
mainLoop:
jal FuelMixing
yield
j mainLoop
FuelMixing:
lbn r0 STBI FuelTank TotalMoles Average
bgt r0 MaximumFuelMoles FuelMixingClose
lbn r0 STBI VolTank TotalMoles Average
blt r0 MinimumVolMoles FuelMixingClose
lbn r0 STBI O2Tank TotalMoles Average
blt r0 MinimumO2Moles FuelMixingClose
lbn r0 STBI VolTank Temperature Average # T1
lbn r1 STBI O2Tank Temperature Average # T2
lbn r2 SPA AfterMixPA TotalMoles Average
lbn r3 SPA AfterMixPA RatioVolatiles Average
lbn r4 SPA AfterMixPA RatioLiquidVolatiles Average
add r5 r3 r4 # Vol Ratio
mul r6 r2 r5 # Vol Moles
lbn r2 STBI FuelTank TotalMoles Average
lbn r3 STBI FuelTank RatioVolatiles Average
lbn r4 STBI FuelTank RatioLiquidVolatiles Average
add r3 r3 r4 # Vol Ratio
mul r5 r2 r3 # Vol Moles
add r6 r6 r5 # m1: Total Vol Moles
lbn r2 SPA AfterMixPA TotalMoles Average
lbn r3 SPA AfterMixPA RatioOxygen Average
lbn r4 SPA AfterMixPA RatioLiquidOxygen Average
add r5 r3 r4 # O2 Ratio
mul r7 r2 r5 # O2 Moles
lbn r2 STBI FuelTank TotalMoles Average
lbn r3 STBI FuelTank RatioOxygen Average
lbn r4 STBI FuelTank RatioLiquidOxygen Average
add r3 r3 r4 # O2 Ratio
mul r5 r2 r3 # O2 Moles
add r7 r7 r5 # m2: Total O2 Moles
lbn totalOutputVolume SPA AfterMixPA Volume Average
lbn r8 STBI FuelTank Volume Average
add totalOutputVolume totalOutputVolume r8
# r' gas mixer ratio, r" target ratio
# b=(1-r") * m1 - r" * m2
sub r9 1 FuelTargetRatio
mul r9 r9 r6
mul r10 FuelTargetRatio r7
sub r9 r9 r10 # b
# r' = (b x T2 - r" x V x 12.2) / ( b x (T2-T1) - V x 12.2)
mul r10 r9 r1
mul r11 FuelTargetRatio totalOutputVolume
mul r11 r11 12.2
sub r10 r10 r11 # r9: numerator
sub r11 r1 r0
mul r11 r9 r11
mul r12 totalOutputVolume 12.2
sub r11 r11 r12 # r10: denominator
div r10 r10 r11
bnan r10 ra
mul r10 r10 100
breqz ReverseMixerInput 2
sub r10 100 r10
sbn SGM FuelGasMixer Setting r10
sbn SGM FuelGasMixer On 1
j ra
FuelMixingClose:
sbn SGM FuelGasMixer On 0
j ra

[mahashma]

Originally posted by Torn4dO:

Are you sure both gasses are EXACTLY the same temperature?
I would recommend a IC to control the setting of the gas mixer, that way it doesn't matter what the temperatures are.

alias H2tank d0 #PipeAnalyser/Tank for input pipe 1 
alias O2tank d1 #PipeAnalyser/Tank for input pipe 2 
alias mixer d2 
define ratio 2 # ratio input1 to input2 

start: 
yield 
l r0 H2tank Temperature 
l r1 O2tank Temperature 
mul r0 r0 ratio 
add r1 r1 r0 
div r0 r0 r1 
mul r0 r0 100 
s mixer Setting r0 
j start

This might be the simplest solution. I'm using heat exchangers to equalise H2/O2 temperatures but I do get some fluctuations, and that seems to be where the fault lies. I am using pressure regulators on both infeeds, but I may have to expand the ballast on it a little to minimise pressure fluctuations.

It's just the first time I've ever had a mixer output an incorrect ratio before, and it had me puzzled.

This is the first game I've ever encountered where even a modest creative build has taken me... 44 hours at this point. And I'm still only maybe 2/3-3/4 done. I have yet to put in all the monitoring consoles, there's frames EVERYWHERE I need to weld up, and I still haven't installed the slightly insane combustor/stirling/filtration management IC10's that keep everything from spontaneously disassembling itself. Oh, and then there's the temperature control system for the O2/CO2 atmo cycle. And probably another 12 things after that I've forgotten.

[Torn4dO]

Originally posted by mahashma:

This might be the simplest solution. I'm using heat exchangers to equalise H2/O2 temperatures but I do get some fluctuations, and that seems to be where the fault lies. I am using pressure regulators on both infeeds, but I may have to expand the ballast on it a little to minimise pressure fluctuations.

It's just the first time I've ever had a mixer output an incorrect ratio before, and it had me puzzled.

Yeah easiest solution I know anyway, using heat exchangers is never reliable cause they will be off once you start to refill your supply. Also what makes the gas mixer a bit different is that you don't need to take pressure into account, just the temperature, which makes it a bit confusing at times. For example, right now I'm on Vulcan. I have Volatiles at 10MPa, but my oxygen is only 40-50KPa as I don't have many plants to produce alot of O2. This doesn't matter at all, as my fuel is always a perfect mix off 66.7/33.3.

Originally posted by mahashma:

This is the first game I've ever encountered where even a modest creative build has taken me... 44 hours at this point. And I'm still only maybe 2/3-3/4 done. I have yet to put in all the monitoring consoles, there's frames EVERYWHERE I need to weld up, and I still haven't installed the slightly insane combustor/stirling/filtration management IC10's that keep everything from spontaneously disassembling itself. Oh, and then there's the temperature control system for the O2/CO2 atmo cycle. And probably another 12 things after that I've forgotten.

IMO that's the beauty of this game, it's complex and there's always more to do!

[WussyBoy]

Every time you guys post your code I learn new things. Thanks for sharing!

[mahashma]

Originally posted by Torn4dO:

Yeah easiest solution I know anyway, using heat exchangers is never reliable cause they will be off once you start to refill your supply.

Thankfully it's not really a huge problem for fuel mixes, but when it comes time to start doing specific gas mixes for base atmo I'll have to be a bit more careful in how it all goes together.