Separation inside the vessel isn't powered by anything mechanical, it's gravity acting on the difference in density between the phases. Gas is far less dense than liquid, so gas and liquid pull apart quickly with almost no help needed. Oil and water are a different story, they sit much closer together in density, so they separate slowly and need residence time inside the vessel to finish the job.
Droplet size plays into this too, and it's the reason a separator isn't just an empty tank. The training module covers which internals force smaller droplets together so they can settle out on a timeline the vessel can actually work with.
The stream's first stop inside the vessel breaks its momentum the moment it arrives, dropping most of the liquid out of the gas right away. Gas continues up toward the outlet, passing through internals built to catch what gravity alone can't. The liquid settles below, held long enough for gravity to keep separating.
From there, the path depends on how many phases the vessel is built to handle. A two-phase separator sends all of that liquid out through a single outlet. A three-phase separator differentiates further, using an internal that lets oil continue separating from water before each one leaves through its own outlet.
None of the separation work matters if the liquid never leaves the vessel downstream, and that's where pressure comes in. As liquid rises inside the vessel, it changes the pressure holding above it, and that pressure pushes liquid out through the outlet. The training walks through the process step by step, explaining why pressure climbs, why it falls, and what that means for keeping the vessel running.
This whole cycle is set and held by the back pressure valve on the gas outlet. Hold gas back, and pressure rises. Let more of it out, and pressure falls. The valve isn't just controlling gas, it's controlling whether the vessel keeps just enough pressure to move its own liquid along to the next piece of equipment.
