Manual Airlock

The Manual Airlock is a door building used to seal off rooms, control movement, and separate areas without requiring power or automation. It functions as an airtight door rather than a true airlock: when opened, gases and liquids pass through it normally. A proper airlock can be made by combining two airlocks with pumps, but the Manual Airlock itself is simply one part of that kind of setup.

Like other doors, it can be built horizontally by rotating the blueprint before placement. When closed, Manual Airlocks count as floor tiles, but when open they do not. Unlike Pneumatic Doors, buildings can be placed on top of them even though they can serve as a floor tile when closed. This makes them useful in compact designs where the top surface must remain buildable.

Manual Airlocks and Mechanized Airlocks do not take damage from high liquid pressure, which makes them especially useful for large reservoirs, liquid locks, and high-pressure liquid compressors. Because they are pressure-resistant, they are often chosen for industrial or plumbing-heavy builds where ordinary doors would be a poor fit.

A Manual Airlock can also be built from Uranium Ore. In that form, the door emits radiation only while closed, not while open. The radiation is small, but it extends a short distance around the door and can help clear very low levels of germs. For disinfecting purposes, however, a Mechanized Airlock is generally the better choice.

• Manual Airlocks can be rotated and placed horizontally in blueprint mode.
• Closed Manual Airlocks act like floor tiles.
• They can support buildings above them when closed.
• They are not damaged by high liquid pressure.
• They do not block gases or liquids when open.
• Uranium Ore versions emit radiation only while closed.

There is also a construction bug involving vertical Manual Airlocks: deconstructing one that is surrounded by tiles on the left, right, and bottom creates a natural tile in the bottom cell, made from the same material as the door. The resulting tile has half the mass of the original door.

Although its name suggests full sealing behavior, the Manual Airlock is best understood as a sturdy, pressure-resistant door with some floor-like properties. Its low complexity and lack of power requirement make it one of the most practical early and mid-game doors, while its material variants and pressure immunity keep it relevant in advanced builds as well.