Positive Displacement Pumps: These pumps physically capture and remove gas molecules from the sealed space. One example is the rotary vane pump, where vanes mounted on a rotor push gas out of the sealed chamber as the rotor spins.
Momentum Transfer Pumps: Also known as molecular pumps, these pumps use high-speed rotating blades or other mechanisms to transfer momentum to gas molecules, propelling them out of the chamber.
Entrapment Pumps: These pumps capture gas molecules by adsorbing or absorbing them onto surfaces within the pump. Cryogenic pumps, for example, use extremely low temperatures to condense and trap gas molecules.
Steam Ejectors: This type of pump uses high-speed steam or gas jets to entrain and remove gas molecules from the chamber.
