Suction pipes are liquid transportation pipes. When attached to a non-pipe Liquid Tank, they automatically attempt to output liquid into said tank. Pipes can be configured to pull liquid from said tanks, instead. Pipes are always on - they either pull, or push, liquid. Suction Pipes use a system similar to the power algorithm.
Pipes maintain a pressure value. Pipes that are pulling from tanks have higher pressure, the greater the amount of liquid in said tank. Pipes that are pushing into tanks have a negative pressure, where there is more negative pressure the more empty room in the tank this is. As such, when a pipe distributes its liquid, it divides its storage among all neighboring pipes with lesser pressure. This ensures that liquid flows from areas of high pressure to low pressure, with more liquid going to locations that have more room for it.
This continues the trend of being server friendly, for the same reasons as the power system.
Vacuum tubes are all-purpose item transportation devices. These are one-directional tube systems whose sole purpose is simply to move items from one place to another. A vacuum tube only has one input, and one output. Pipes have 4 slots, with an emergency fifth overflow slot. Every tick, vacuum tubes with their inputs attached to inventories pull an item stack from the inventory, and propagate forward all items already in the tube, 1 slot forward. If a vacuum tube cannot move items out of it, such as if the inventory at its output is completely full, and no item stacks can be combined, then the pipe begins to overflow. This is signified by the slot marker turning red. This can cause backups down the pipe system as each next pipe fills up and begins to overflow.
If vacuum tubes have empty space as their input, they attempt to suck in all items in a 1 block area of the end, pulling them into the system. This behavior is disabled if the tube is overflowing. Tubes with no output inventory, when moving the 4th slot, will eject the item into the world. This keeps the flow of items moving, and can be used for trash disposal, etc. Tubes, once placed, can be manipulated to change direction or attach to different tube systems.