"Now," Elias said, his voice dropping an octave. "Here is where most young engineers fail. They buy a pump for the air load, turn it on, and the pump overheats and shuts down in ten minutes. Why?"
) is based on the volume to be evacuated and the desired time: vacuum pump capacity calculation xls
| Parameter | Symbol | Value | Unit | |-----------|--------|-------|------| | Chamber volume | V | 500 | Liters | | Starting pressure (atmospheric) | P_start | 1013 | mbar | | Target pressure (vacuum level) | P_target | 0.01 | mbar | | Desired pump-down time | t_desired | 10 | minutes | | System leak rate (estimated) | Q_leak | 0.05 | mbar·L/s | | Outgassing rate (per surface area) | q_outgas | 1.0E-06 | mbar·L/(s·cm²) | | Internal surface area | A_surface | 5000 | cm² | | Process gas load (e.g., water vapor) | Q_process | 0.02 | mbar·L/s | | Conductance between pump & chamber | C | 100 | L/s | "Now," Elias said, his voice dropping an octave