Liquid lock issues.

[Frustrated]

There are times when my 3-fluid liquid locks will just randomly collapse when a dupe walks through them.  Is there something I'm doing wrong when creating them?

[Charletrom]

I’ve never used 3-high locks before, but bead locks and two-tile locks are pretty unreliable. The small mass is susceptible to flash boiling/freezing if a dupe carries something hot/cold through. Using naphtha as the bottom layer mitigates this since the droplet holds more mass.

Or it could be a fart.

[Frustrated]

They're 2 high locks with a dip, but use 3 fluids.  I use brine, salt water, clean water.  The idea is the fluid blocks gasses due to overpressure, but the sprite jumps the gap and doesn't get wet.

[Charletrom]

Hmm never tried that approach, but seems like it would still be susceptible to boiling or freezing. I usually use naphtha beads or two-tile naphtha/petroleum locks. These require atmosuits to prevent the soggy feet condition.

[Frustrated]

I'm too early in my playthrough to have discovered the oil biome.  Marsh, snow, tidepool, and caustic so far.  It's worked just fine for me so far, just became a headache at the absolute worst time when there was a slimelung outbreak in one of the marsh biomes my dupes travel through.  I sealed it off before anything could happen though.

Edited February 2 by Frustrated

[myxal]

A screenshot would be useful. What's on either side of the lock? Have you removed all the sublimators before placing down the lock? Can anything fall into the lock (debris struck and launched by meteor? Bleach stone hopper yeeting bleach stone into it?) Sponge slug/sweepy/gulp fish/dartle/rhex on the loose? Is there a ladder in the dip or something else that makes dupes walk through the lock instead of jumping over? Gas condensing into liquid nearby (steam or ethanol)?

I've only ever used stacked liquids inside the base, and even then the juice wasn't worth the squeeze vs, bead locks or putting the build outside in suited area and using bead or full-size locks. Can't even imagine trying to use them during exploration.

Edited February 3 by myxal

[Frustrated]

This is how it looks now.  As I said, I sealed it off before the germs could get close, and I've been considering retrying it...if I can finish my hydra and resolve my oxygen issue...and resolve my clean water issue.

[Gurgel]

Liquid locks based on small quantities of liquids are unreliable. Small quantities of fluids can be displaced, evaporated or erased by a number of effects. I have observed that several times and I only use them as short-term temporary locks. 

Edited February 6 by Gurgel
typo

[Frustrated]

What's a small quantity?  I use 140kg brine, then 30kg each of the other two.  And what do you suggest I use in the early-mid game before I have the ability to get to an oil biome or somewhere I can get naptha or petroleum?

Edited February 6 by Frustrated

[myxal]

2 hours ago, Frustrated said:

then 30kg each of the other two.

I believe you meant 30g, waters spill at quantities over 32g or so .

2 hours ago, Frustrated said:

And what do you suggest I use in the early-mid game before I have the ability to get to an oil biome or somewhere I can get naptha or petroleum?

Full-size (V-trough) locks or several step-down bead locks. Faffing about with stacked liquids to avoid wet feet debug is not worth it early game, though I have to admit I've not played with bionics yet.

[Charletrom]

3 hours ago, Frustrated said:

What's a small quantity?  I use 140kg brine, then 30kg each of the other two.  And what do you suggest I use in the early-mid game before I have the ability to get to an oil biome or somewhere I can get naptha or petroleum?

Consider ranching glossy dreckos, which produce plastic that can be melted into naphtha. 

[Gurgel]

21 hours ago, Frustrated said:

And what do you suggest I use in the early-mid game before I have the ability to get to an oil biome or somewhere I can get naptha or petroleum?

Use the ''classic 1-Fluid "Staircase" Liquid Lock'': https://oxygennotincluded.wiki.gg/wiki/Guide/Liquid_Airlock

I use them all the time, sometimes with active cooling or heating. Usually just with plain water, sometimes with other liquids. 

 

Edited February 7 by Gurgel

[Frustrated]

On 2/6/2026 at 6:56 PM, Charletrom said:

Consider ranching glossy dreckos, which produce plastic that can be melted into naphtha. 

It would truly be nice if I could find the space to build any sort of ranch.  I'm annoyed with myself.  I somehow managed to excavate germy slime and dump it into my algae distiller.  Had to completely restart but I'll keep that in mind as I build my new place out.

Here's a pic of the 3-fluid lock I've been using.

 

[Charletrom]

22 hours ago, Frustrated said:

It would truly be nice if I could find the space to build any sort of ranch.  I'm annoyed with myself.  I somehow managed to excavate germy slime and dump it into my algae distiller.  Had to completely restart but I'll keep that in mind as I build my new place out.

Here's a pic of the 3-fluid lock I've been using.

 

A minor modification could help, which is to add a single block one tile away from the lock on both sides. This would block spilled water/liquid from flowing into the lock and breaking it. Pee for example.

[Frustrated]

I appreciate the advice.  I don't think it's spillage.  It's probably what they were talking about: too much mass or too much heat passing through.

[Frustrated]

I don't know why this looks like this...

I mean it works, but it doesn't look the same as the other one's I've crafted.

[Alexander Block]

@Frustrated Heavy gas that cannot rise up.

[Frustrated]

It's pO2 on one side and O2 on the other.  It was all O2 when I first created it.  I'm not hugely worried because it's blocking gas movement, I just thought it looked weird.

[Fleetfeet]

That isn't a packet of co2 on the right?

My assumption is that it was, as a dupe helpfully breathed the available o2 while standing in that (previously a) puddle, emitted a lil packet of co2 that displaced the water, and then just sat there because it's heavier than o2.

[Frustrated]

Unlikely, given that I have an atmo dock before the liquid lock, so the CO2 would be blocked by the block on the right.

[Gurgel]

On 2/10/2026 at 6:35 PM, Frustrated said:

I don't know why this looks like this...

I mean it works, but it doesn't look the same as the other one's I've crafted.

There is some CO2 on the right side. To get rid of it, build a block there and then immediately deconstruct it. That should solve it permanently. 

Edited February 13 by Gurgel

[Frustrated]

*Something* happened and now there's a bit of polluted water on one side

 

I have no idea where it came from, but the lock is not far from a snow biome and there's pO2 everywhere, so it might have condensed.

[arvenil]

On 2/6/2026 at 5:38 PM, myxal said:

Full-size (V-trough) locks or several step-down bead locks

What is a "several step-down bead locks"?

[Gurgel]

20 hours ago, Frustrated said:

*Something* happened and now there's a bit of polluted water on one sideI have no idea where it came from, but the lock is not far from a snow biome and there's pO2 everywhere, so it might have condensed.

That is probably some polluted ice that was dropped in that tile and then melted.

Or a dupe did not make it to the toilet and had an accident in the lock. But that produces only about 2kg of pwater per "mess" and would have Food Poisoning in it.

pO2 will freeze into clean liquid oxygen, so that cannot be it.

[Frustrated]

It's probably the first then, because that lock was very close to a snow biome.