Fluid Bus

Make your whole fluid main bus behave like one single tank.

In Factorio 2.0 a long pipeline has to be split by pumps (a fluid segment may span at most 320 tiles).
Pumps push only one way and at most 1200/s, so a secondary source can't feed anything "upstream",
the bus overfills in front of a pump and runs dry behind it.

Bus couplers join all segments of BUS pipes into one network and keep their fill level even –
no matter how long the bus is or where the inputs and outputs are.

Features

• BUS variants of every pipe in the game – vanilla and modded (Pyanodon, Bob's, …), with the same
  properties as the original. Recognize them by a spray-painted black "B".
• Bus coupler (1×1, electric) – place it in the bus instead of a pump. It connects only to BUS
  pipes, so the "one tank" bus needs dedicated infrastructure.
• Exact conservation – fluid amount and temperature (steam) are preserved.
• Circuit network – both values under the icon of the fluid in the bus: red wire = amount,
  green wire = fill %. Burn the surplus only above 90 %, start a backup source below 30 %.
• Circuit control – disable a coupler by a condition (like a pump); the Bus balancing interval
  signal sets how often its network is balanced.
• Status in the coupler window – network size and fill, no power, not connected, mixed fluids.
• Status light on the coupler: green = powered, yellow = low power, red = no power (glows at night).
• UPS friendly – networks are balanced every 5 ticks by default (map setting), large buses are
  spread over ticks; see Performance below.

How to use

1. Research Fluid bus (after advanced circuits in vanilla; in overhaul mods after the techs of the coupler ingredients).
2. Build the bus from BUS pipes – or upgrade your existing bus: build BUS pipes over the old ones
   (fluid is kept) or use the upgrade planner.
3. Replace the bus pumps with bus couplers and power them.
4. Connect inputs and outputs with ordinary pipes and a pump right next to the bus.

 before:  source ─══════[P]══════[P]══════[P]══════─   (flows one way only, max 1200/s)

 after:   input ─[pump]─┐                    ┌─[pump]─ factory
          ═══B══════════╧═══[C]═══B═══…═══[C]╧══════B═══
          [C] = bus coupler   B = BUS pipe   whole bus = one tank

Settings

• Bus coupler power (startup) – default 50 kW.
• Balancing interval (map setting, changeable while playing) – default 5 ticks. Every N ticks a
  coupler network is balanced as a whole in one tick; afterwards all segments have the same fill %.

Fast pumps (12,000/s and more)

There is no fixed flow cap. Between two balancing ticks the fill of segments drifts by about
2 × flow × interval / segment capacity – e.g. 12,000/s with interval 5: ±10 % for 100-pipe segments,
±3 % for 300-pipe segments. Lower the interval for short segments and very fast pumps.

Performance

Factorio 2.0.77, balancing interval 5 ticks, script time after warm-up:

Compatibility

Tested (headless integration tests) with: vanilla, Space Age, Pyanodon's modpack, Bob's Logistics,
Pipe Tiers. BUS variants are generated from all pipes in the game, so other pipe mods should work too.

Known limitations

• A coupler's enable condition also sees the coupler's own output signals (amount + fill % under
  the fluid icon). Base the condition on a different signal.
• Steam of different temperatures in one network is mixed (weighted average) – keep 165 °C and
  500 °C steam on separate buses.
• Two couplers directly next to each other do not connect – put at least one BUS pipe between them.