# HELP WANTED - Why is steam not water under 100C

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This is getting quite annoying, as it is over-pressuring my steam vent.

Is this a bug?

Any ideas on how to fix it?

If more pictures are required just ask.

Thanks!

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Much like in real life, substances have activation thresholds (I believe that's the term), which is basically a range where it will remain in either of two states.

In ONI this is represented by ~4 degrees K either side iirc, so your steam should condense around 95C.

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34 minutes ago, Yunru said:

, substances have activation thresholds (I believe that's the term),

"heat of vaporization" is probably a better term for it. It takes energy/heat to convert water into steam and this heat input doesn't change it's temperature, only it's phase. So, when (real) water is at exactly it's boiling point, there is a time where adding more heat will convert more of it to steam, without increasing its temperature. Only after it's entirely converted will the temperature increase.

38 minutes ago, Yunru said:

In ONI this is represented by ~4 degrees K either side iirc, so your steam should condense around 95C.

Specifically, in ONI,  each element has a nominal phase change temperature. For water this is 99.35C. But you have to go 3C beyond that temperature for a phase change to occur. So 96.35C to condense steam. When that happens, the temperature of the new substance is reset 1.5C towards the nominal phase change temp. So water will be created at 97.85C

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To complete above I just add:

It's hysteresis. It's to avoid toggling between states.

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16 minutes ago, sheaker said:

To complete above I just add:

It's hysteresis. It's to avoid toggling between states.

I remember I first learned about it when I asked my teacher why water at 0C didn't have this weird state of being water and ice almost at random.

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2 hours ago, sheaker said:

To complete above I just add:

It's hysteresis. It's to avoid toggling between states.

Yep. Keeps the universe from exploding....

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On 1/23/2021 at 4:54 PM, ghkbrew said:

"heat of vaporization" is probably a better term for it. It takes energy/heat to convert water into steam and this heat input doesn't change it's temperature, only it's phase. So, when (real) water is at exactly it's boiling point, there is a time where adding more heat will convert more of it to steam, without increasing its temperature. Only after it's entirely converted will the temperature increase.

Specifically, in ONI,  each element has a nominal phase change temperature. For water this is 99.35C. But you have to go 3C beyond that temperature for a phase change to occur. So 96.35C to condense steam. When that happens, the temperature of the new substance is reset 1.5C towards the nominal phase change temp. So water will be created at 97.85C

The game mechanics work less like this; and more like supercooling/heating. In real life; you can have water outside that is below 0 C; because crystalization has not started yet. It happens sometimes if you leave a bottle in the freezer, esp when the water is pure. This is more accurate description of what the game models. Hysteresis here is the accurate term.

On 1/23/2021 at 11:32 PM, Yunru said:

I remember I first learned about it when I asked my teacher why water at 0C didn't have this weird state of being water and ice almost at random.

IRL it makes sense; but sometimes the game will get stuck with this toggle between states; since it has no latent heat simulation.

I know I'm being pedantic here; but also think supercooled water is really fun.

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5 hours ago, silverbluep said:

no latent heat simulation

On 1/24/2021 at 1:54 AM, ghkbrew said:

When that happens, the temperature of the new substance is reset 1.5C towards the nominal phase change temp.

In my head this is the latent heat part of the simulation, even though the temperature doesn't stall. You have to pay 1.5C extra to phase up and you get back 1.5C when you phase down.

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On 1/23/2021 at 4:54 PM, ghkbrew said:

When that happens, the temperature of the new substance is reset 1.5C towards the nominal phase change temp. So water will be created at 97.85C

Wait is this true? I did not know this.