How does a rotary vane vacuum pump work?

A rotary vane vacuum pump is a type of positive displacement pump commonly used to create a vacuum by removing air or gas molecules from a sealed volume. Here's how it works:

Basic Components:

1. Rotor – Mounted off-center inside the pump chamber.

2. Vanes – Usually two or more, placed in slots in the rotor. They are free to slide in and out.

3. Pump Chamber (Casing) – A cylindrical housing in which the rotor spins.

4. Inlet & Outlet Ports – For gas intake (vacuum side) and exhaust (atmospheric side).

5. Oil (in oil-sealed pumps) – Provides sealing, lubrication, and cooling.

Operating Principle:

1. Intake Phase:

   • As the rotor turns, centrifugal force (and/or springs) pushes the vanes outward so they stay in contact with the inner wall of the chamber.

   • The volume between two vanes increases as the rotor turns, drawing gas in through the inlet port (creating a vacuum in the connected system).

2. Compression Phase:

   • As the rotor continues turning, the gas gets trapped between two vanes and the chamber wall.

   • This volume shrinks as it moves toward the outlet side, compressing the gas.

3. Exhaust Phase:

   • When the trapped gas reaches the outlet port, it's at a higher pressure than outside, and it's pushed out.

   • In oil-sealed versions, oil also helps prevent backflow and assists in maintaining a good seal.

Continuous Operation:

The cycle repeats continuously as the rotor spins, pulling in more gas and expelling it to the atmosphere (or next stage in multi-stage systems).