Vacuum Pump Capacity Calculation Xls !!top!!

To calculate the required vacuum pump capacity, follow these steps:

This calculates how long it takes to pull a vacuum on a specific volume. 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 | To calculate the required vacuum pump capacity, follow

cap S equals the fraction with numerator cap V and denominator t end-fraction center dot l n open paren the fraction with numerator cap P sub i n i t i a l end-sub and denominator cap P sub f i n a l end-sub end-fraction close paren Excel Syntax: = (V / t) * LN(P_init / P_final) Steady-State Capacity (Leakage/Process Loads): is the total gas load (leaks + process vapors) in Mechvactech 2. Spreadsheet Structure Recommendation Required Pumping Speed (Sizing): Used to select a

t equals the fraction with numerator cap V and denominator cap S end-fraction center dot l n open paren the fraction with numerator cap P sub i n i t i a l end-sub and denominator cap P sub f i n a l end-sub end-fraction close paren Excel Syntax: = (V / S) * LN(P_init / P_final) = Volume (L), = Pumping Speed (L/s), = Time (s), = Pressure (Torr or Pa). Required Pumping Speed (Sizing): Used to select a pump based on a required time frame.

Lucas added a multiplier. "If we assume peak vapor load during the first few minutes doubles the gas volume, the pump might stall."