Tutorials/Airlock

Airlocks are structures effective at preventing water from spreading into buildings. The airlocks shown here will close in the event of flooding, but will not reopen until the player breaks them.

Airlocks were designed for the Indev version of Minecraft. Airlocks can still be constructed in Beta, but the range of blocks usable for the purpose has increased.

Airlock Mechanics
Airlocks rely on the properties of the torch, sand, and water to function.


 * Torches can support other blocks and turn back into an item if the block it is attached to is removed, or if it is exposed to water.


 * Sand will always attempt to fall and can be supported by a torch.


 * Water flows outwards, but will dry up if not connected to a block of still water.

When a torch with sand on top of it touches water, the sand drops and stops water flow in that direction. If torches are attached to any of the blocks above, then that torch will break as well. This will continue to the very last torch.

Airlocks are one of very few reactions to require no direct human influence.

Construction
An airlock requires only two components, a block affected by gravity (such as sand) and torches (regular or Redstone).

When placing an airlock, be sure to think about choosing narrow passageways and choke points, so that less time is spent on the project. For a building with multiple entrances, multiple airlocks may be needed to achieve optimal dryness.

Airlocks are usually built directly across the hallway. Most sand-based airlocks are only 1 block thick, due to the fact that only 1 layer of sand is needed to stop the water.

Determining the materials needed is simple enough. The number of torches is equal to the width of the corridor, and sand is equal to the width of the corridor times the height of the corridor. Optionally, a shovel and a pickaxe can be taken along, to speed up digging and to waste less time on mistakes.

For the first step, the hallway must have a ceiling height equal to the highest water level possible plus 1, to compensate for the torch. Also, each new column must be 1 block higher, as the torch is 1 block higher each time.

A torch is placed on either wall at a level where water can contact it and there is enough space above to provide the required amount of sand to seal the chamber.

Sand is now placed above the torch until the sand reaches the ceiling, or until it reaches the desired level.

(A 1 block wide hallway is complete at this step)

A passageway more than 1 block wide must be extended from wall to wall in a particular fashion. A torch is placed on the block of sand above the previous torch, and sand is placed above that. This process is repeated until the hall is waterproofed.

Other Uses
Airlocks are one of the first completely environmentally reactive traps in Minecraft

The use of Airlocks in stopping water flow can also be applied to the concept of controlled flooding, allowing one to flood an area until a certain water level or redirect it when those levels are reached.

Example of Player triggered trap using the torch/sand concept The airlock works essentially the same, but faster and directly controlled by water flow, and not player interaction (Making it a completely standalone mechanism), Although this video proves that the method can be used to effectively trigger multiple walls and seal off multiple areas.

The torch system could also trigger sand falling into a room, where a hole in the ceiling then opens up and lava then pours in to cancel out the water. As long as it involves the movement of sand and water, it's quite an effective trigger system.

Uses in Creative Mode
By using flowers/mushrooms you may be able to build a less effective version of this airlock, since mushrooms/flowers are removed when in contact with a water/lava square. However the efficiency of simply using Trees to block water/lava makes sand based airlocks much less worthwhile.

Trivia

 * Torches will also support gravel, but the gravel must be placed, not dropped, on the torches, as it breaks without producing any flint.
 * Regular torches can also be substituted with Redstone Torches, but this is usually pointless, due to the increased expense.
 * In Beta, Sugar Cane can be used as a type of airlock, though this presents the difficulty of growing it inside.
 * Since the introduction of Pistons, they can be used to make much more compact airlocks using the same basic techniques. Piston-based airlocks are not restricted to using sand or gravel, but they may require redstone circuitry which tends to make them costlier and more complex than torch/sand or torch/gravel airlocks.

Video Guide

 * How to build an airlock

Anleitungen/Wasserschutztür Tutoriels/Sas Аирлок