How to release gas from liquid pipe?

[Sad_Brother]

Condensation Valve move liquids from gas pipe to liquid pipe and it is perfect.
Why there is no such device to reverse process?

Expansion Valve move liquid. It would stress gas pipes.
Purge Valve move gas from liquid pipe to gas pipe but will blow gas pipe if not controlled.
Pressurant Valve move gas to liquid pipe so not usable for this.
Even Evaporation Chamber have inbuilt back pressure regulator.

How to allow gas to move out from liquid pipe to lower pressure gas pipe? Why such simple and needed valve absent? Is it possible without active control?

If some one way valve would allow only gas to move from liquid pipe to gas pipe it would be perfect. From gas to liquid would be good as well.

[Daggoth]

Purge valve is what you want.
It needs to be controlled/powered for two reasons:
- Uncontrolled purging would cause a loop of - gas is purged -> pressure drop in liquid pipe -> more liquids hit gas phase change pressure and evaporate -> gas is purged -> pressure drops in liquid pipe. And equally, the purged gas would pressurise and may re-condense, causing stress on the gas pipe.
- Devs have decided that pressure controllers have to be powered. Pressure regulator, back pressure regulator, pressurant valve, purge valve, etc.

[WussyBoy]

Pressure in a closed liquid pipe is controlled by the temperature. The liquid and gas is in a pressure equilibrium. If the temperature goes up, more evaporation happens and the pressure rises. If the temp goes down there is more condensation and pressure drops.

This is why you can’t just remove the gasses and leave the liquids.

I’m guessing you want to moves gasses out of a pipe for another purpose. If you are getting too much liquid in your gas pipes, expand the gas pipe volume. This works downstream of the expansion valve.

You mentioned condensation valves and that they work perfect, but as you probably already know it’s easy to rupture the gas pipe before the condensation valve. The solution is to A) slow down the gas flow or B) increase the pipe volume. Perhaps doing both is the solution.

As mentioned, a purge valve will move only gas (which caused the liquid to evaporate in the liquid pipe more) but costs some power. Expansion valves will move both gas and liquid and require no power, but you’ll have to provide adequate volume for the gas to expand into so pipe stress is minimal.

[CPT Chthonbeard the Pirate]

Look at the pipes in your house, they have gasses in them when there is no liquid in them or they are not completely full of liquid. This is a normal state for them. Nature abhors a vacuum. Outside air will rush in to fill the volume to equalize the pressure.

In game they represent this by having the liquid vaporize until pressure is equalized. This is not quite realistic, but it is realistic that there will not be a vacuum filling the remaining volume. There will be gas pressure. The gas must come from somewhere. As the pipe fills, and the pressure rises, the gas will condense again into liquid.

If it is truly a problem, you can use a purge valve, but more gas will vaporize from your liquid, until you have no liquid left. Furthermore, in your gas pipes, the vapor will condense, requiring a condensation valve to return it to your liquid pipes again. This will eventually result in a powered system because of the purged valve that just equalizes with gas and liquid in both sets of pipes at a certain level, and you will never be happy.

Just accept how physics works in the game. Don't overfill your tanks, and let the liquids fill the volume by vaporizing.

[Sad_Brother]

Originally posted by Daggoth:

Purge valve is what you want.
It needs to be controlled/powered for two reasons:
...
- Devs have decided that pressure controllers have to be powered. Pressure regulator, back pressure regulator, pressurant valve, purge valve, etc.

That is exactly why I do not want it. I would need to set pressure after controller as setting to valve. And it would pump where passive valve should be enough.

Originally posted by WussyBoy:

Pressure in a closed liquid pipe is controlled by the temperature. The liquid and gas is in a pressure equilibrium. If the temperature goes up, more evaporation happens and the pressure rises. If the temp goes down there is more condensation and pressure drops.

This is why you can’t just remove the gasses and leave the liquids.
...

I do not want to remove all gases, only allow gases to move from liquid pipe to gas pipe. But forbid liquid. I want liquid to evaporate in liquid pipe only.

Originally posted by CPT Chthonbeard the Pirate:

Look at the pipes in your house,..

It seems I need to explain better.
I do not want to remove gas from liquid pipe.
I want to release eccess gases to gas pipe with lower pressure.

Simple one way valve should help but it is for gas-gas pipes only.

[God, owner of the Universe]

And the Purge Valve, whose back-pressure you can define (so, you can simulate the idea of "excess gas escapes") is not suitable because

- needs power
- the set value should change based on what "excess" means, which changes with liquid temperature

? Or are there more/other reasons?

[Sad_Brother]

Need for power annoying but not critical.
Critical is the need to control. Without it gas pipe would risk to become empty or blowed.

[WussyBoy]

Originally posted by Sad_Brother:

Originally posted by WussyBoy:

Pressure in a closed liquid pipe is controlled by the temperature. The liquid and gas is in a pressure equilibrium. If the temperature goes up, more evaporation happens and the pressure rises. If the temp goes down there is more condensation and pressure drops.

This is why you can’t just remove the gasses and leave the liquids.
...

I do not want to remove all gases, only allow gases to move from liquid pipe to gas pipe. But forbid liquid. I want liquid to evaporate in liquid pipe only.

Yeah, the purge valve is the only option here. There is no simulation of gravity in the pipes, so you can't just create an escape for the gas above the level of the liquid, and even if it did, there is no unpowered regulator.

[RA2lover]

A liquid volume pump set to 0 L moves gases from the input pipe to the output pipe in a manner similar to a gas-only one-way valve without consuming power, but that only moves gases from a liquid pipe into another liquid pipe.

You can then get those gases into a gas pipe by venting that liquid pipe's gases into a closed room with a passive liquid inlet, and collecting the gases into a gas pipe with a passive vent (though it will still fill with liquid if the room gets flooded to the point the vent gets submerged).

[Sad_Brother]

Oh, mighty RA2lover! Great thanks from wiki reader!
Is it true? Would Liquid Volume Pump allow gases even unpowered?
If so would Expansion Valve later allow gases or it restricted to liquids only?

[RA2lover]

It still needs to be powered - it's just it consumes a negligible amount of power.

Just tested it on my end and while setting it to 0 fails as if the pump was unpowered, setting it to 0.0000001 L with a labeler works while consuming a negligible 2 microwatts of power.

As for the expansion valve - it's just a condensation valve with the difference that it moves liquids from a liquid to a gas pipe instead of moving liquids from a gas to a liquid pipe. In either case, if the input pipe only contains gases, nothing is transferred. That's why the room-sized liquid-pipe-to-gas-pipe interface adapter needs to be there.

[WussyBoy]

RA2lover - Doesn't this work because the liquid pump is simply pumping a tiny amount of liquid into the pipe which nearly instantaneously evaporates, forming gas?

So in effect, it's just metering a tiny amount of liquid, not any gas.

[Sad_Brother]

It could be tested when gas and liquid are different.

[RA2lover]

Originally posted by WussyBoy:

RA2lover - Doesn't this work because the liquid pump is simply pumping a tiny amount of liquid into the pipe which nearly instantaneously evaporates, forming gas?

So in effect, it's just metering a tiny amount of liquid, not any gas.

No, because the amount of gas pumped and evaporated is too small compared to the amount of gas moved between the pipes.

At the 0.0000001 L figure, you'd be moving 5.55 micromols/tick of water (the densest liquid in mols/L), which would only be enough to raise the pressure by 1.26 Pa for a single 10L pipe segment at 273.15 K. Running that pump for a few ticks you've already evened out the pressure, while doing so with just liquid evaporation would literally take an hour per pipe segment despite the water being only at armstrong pressure.

[WussyBoy]

Interesting. Thanks for the explanation. It appears to be an exploit I'd have to try out.

[God, owner of the Universe]

I just tested this, and it doesn't seem to work. I got 0.001 L of water on the other side - and 0.5ish moles of gas, in a ~5 pipe volume. Input was also ~5 pipes connected to a water tank on a portables connector.

So, at first glance, we got tons of gas over the line (though temperature was half a degree lower). But afterwards, no more gas was coming - it was saturated. Only water was added.

So, maybe it's an exploit - but it only gives you 1 mouthful.