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### Handling Excess gases with flare stacks

Posted: Sun Oct 24, 2021 9:07 am
Hi,

i am loosing my sanity over this problem, but there might be a very simple solution which i am not capable of seeing.

Problem:

2 train stations, one gets hydrogen, the other gets chlorine. both are fed by electrolysis plants which produce hydrogen and chlorine.

now, for example if hydrogen is full, it clogs the chlorine production. therefore i want to send excess hydrogen to flare stacks to make room for chlorine production.

i thought of a simple condition: when hydrogen nearly full, burn it. but the problem here is, that it gets wasted, as when both stations are full, the condition is always true and it burns the resources without need.

so i need a shut off switch, for when both stations are full, nothing will be burned. this is where i fail to produce any circuit that does that.

any input is greatly appreciated!

thank you in advance, and sorry if there is a really simple solution i am unable to comprehend yet.

### Re: Handling Excess gases with flare stacks

Posted: Sun Oct 24, 2021 9:17 am
First an overflow valve or a pump set to hydrogen >= full tank so it never flares hydrogen unless there is excess. Then a pump set to chlorine < 1 train load of chlorine. So it stops flaring when there is enough chlorine.

### Re: Handling Excess gases with flare stacks

Posted: Sun Oct 24, 2021 10:49 am
One solution would be to stop the input of hydrogen when the chlorine tank is full, and put the hydrogen overflow between the pump and the hydrogen tank.

2021-10-24 12_48_03-Factorio 1.1.42.png (2.25 MiB) Viewed 423 times

### Re: Handling Excess gases with flare stacks

Posted: Sun Oct 24, 2021 5:20 pm
IIRC from my Seablock maps, I just solved it with two pumps in series leading to each flare stack. For the hydrogen, one pump is hydrogen > X, the other is Chlorine < X, with types swapped for chlorine. That means one isn't on if hydrogen isn't full enough, and the other isn't on if chlorine is too full. If hydrogen is empty, the first isn't on so nothing gets flared. If hydrogen is full and chlorine isn't, both are on so it gets flared. If both are full, the second is off so the first can't pump so nothing gets flared.

I had used overflow valves for that before but you can't control what percentage they flow at.

### Re: Handling Excess gases with flare stacks

Posted: Sun Oct 24, 2021 5:27 pm
disentius wrote:
Sun Oct 24, 2021 10:49 am
One solution would be to stop the input of hydrogen when the chlorine tank is full, and put the hydrogen overflow between the pump and the hydrogen tank.

2021-10-24 12_48_03-Factorio 1.1.42.png
In that screenshot you don't even need the pump. The chlorine will backlog and stop the electrolysis so no more hydrogen comes in to be flared. And it won't work if chlorine becomes full. He wants to stop when both stations are full. So both need a flare stack to burn away excess.

An alternative to controlling the output of the electrolizers is to control the input instead. Use 2 decider combinators connected to the tanks with: "Hydrogen < 50000 ===> 1 green" and "Chlorine < 50000 ===> 1 green". Put a pump at the input of the electrolyzers, connect it to both combinators and set it to enable on "green > 0".