Expansion Valve

The expansion valve connects two kinds of line: the input is a liquid line, the output a gas line. It has no power and no data port. You open and close it on the valve itself (On).

What it does in the game code: while open, every tick it pushes liquid from the input into the gas line – at most 10 litres and at most half of what is currently in the input network. It does not let gas through, and it does not look at the pressure. Setting (0 to 100) only appears in the logic list because the device inherits it; the valve never reads the value.

The name describes the principle of a refrigerator. If the pressure in the gas line is below the liquid's vapour pressure, it evaporates there. To do so it needs heat of vaporisation – according to the game data, for example, 4,000 J per mole for nitrous oxide (Nitrous Oxide) and 8,000 J per mole for water. That heat is then missing from the gas, and the line behind the valve gets colder.

The way back is taken by the Condensation Valve: it moves liquid that has collected in a gas pipe into a liquid line. Together with a pump that compresses the gas again and a radiator that sheds the heat, you get a closed cooling loop.

It is built from the Kit (Pipe Valve), which also gives the plain valve, the one way valve and the condensation valve. Placing takes one step; you remove it with the hand drill. How phase changes work in the game is covered in Evaporating, condensing, freezing: using phases on purpose.