A pump with a slotted rotor turning off-centre in a cylindrical stator; vanes slide in and out against the wall, trap a pocket of gas, compress it and push it out through an exhaust valve under oil. The oil seals the clearances, lubricates and carries away heat. Two-stage models reach about 10⁻³ mbar, and serve as the workhorse roughing and backing pump wherever a trace of oil is tolerable; clean processes use dry pumps instead to avoid backstreaming and oil changes.
Rotary vane's oil is dark and the ultimate's drifted to 5E-2, it's due an oil change and probably new vanes.
Also heard as
- RV pump
- rotary pump
- oil-sealed pump
Related terms
Mech pump
Lab slang for the oil-sealed rotary vane pump that sits under the bench or behind the tool.
Gas ballast
Controlled bleed of air into an oil-sealed pump's compression stage that keeps vapours from condensing in the oil.
Milky oil
Pump oil turned cloudy or creamy by an emulsion of water, a sign the pump has been swallowing wet loads.
Backstream
Of pump oil or vapour, to flow the wrong way, from the pump back toward the chamber.
Dry pump
Vacuum pump with no oil or liquid in its pumping chamber, used where oil vapour would contaminate the process.