Shop name for the inlet of a high vacuum pump, the round opening under the gate valve. Anything that obstructs the throat, such as a screen, a baffle or a dropped part, cuts the effective pumping speed, and anything that falls into the throat of a running turbo can wreck the rotor. Techs compare pumps by throat size because in molecular flow the inlet area caps the speed a pump can deliver.
Leave the inlet screen in, last time a set screw went down the turbo's throat and it cost us a rotor.
Also heard as
- pump throat
- inlet
Related terms
Turbomolecular pump
High vacuum pump whose rotor blades spin at tens of thousands of rpm and bat molecules toward the exhaust.
Effective pumping speed
The pumping speed actually delivered at the chamber after losses in the connecting pipes and valves.
Gate valve
Full-bore valve with a sliding plate that isolates a high vacuum pump or a load lock from the chamber.
Crash a turbo
To wreck a turbo pump's rotor by letting it hit the stator, most often by venting it hard while it spins.