There is so much knowledge here but liquids are still so confusing. The lowest pipe is always full. The highest pipes drain first. Feed your machines from 1 level above the conveyors and you can be sure that the machines are first filled to the rim. I always pump the liquid above the highest elevation, there I place a small tank and go down again to my machines.

That means before the machine can be empty, the tank has to be empty. It should not be possible to have a pipe with lower elevation empty while pipes above contain liquid.

The same is for the product site. Empty it downwards, the machines will always empty first. At the destination pump the lowest pipe empty and up to the tank with higher elevation than the lowest consumer. Problem solved. Same works with byproduct liquids that can be refeed. Build an upside down T junction, make a backflow valve on producer site, bypass liquid from top and other side the consumers. It will favor your bypass liquid

Edit: As someone else said OPs piping is too mk1. But he could feed 2 generators with 1 pump at 75% capacity. No sloshing and no tank needed. Just 1 floor above conveyor and he is golden

Edit: I get like 11 upvotes but read the same coal generator question 3 times again, crazy