In your XLS, add a data table showing how +20% outgassing affects required speed. This builds confidence.

| Cell | Label | Value / Formula | |------|-------|------------------| | B3 | Chamber Volume (liters) | User input | | B4 | Initial Pressure (mbar abs) | 1013 | | B5 | Final Pressure (mbar abs) | User input | | B6 | Desired Evacuation Time (s) | User input | | B7 | Pipe Conductance (L/s) – if known | User input | | B8 | Outgassing + Leak Correction Factor (default 1.15) | User input |

to your final capacity to account for motor efficiency losses, unexpected outgassing, or minor leaks that develop over time. step-by-step example

"It’s a ratio," Lucas realized. "The volume of vapor is proportional to the ratio of pressures."

Highlight these cells in light yellow to indicate where users must enter physical system properties.

Adds a multiplier (e.g., 1.5 to 2) to ensure reliability. Section 3: Results

Lucas nodded, opening the laptop again. He added a new tab: .

This guide breaks down the engineering mathematics required to size a vacuum pump and outlines how to build a robust spreadsheet. 1. Core Physics and Formulae

when running close to its ultimate blank-off pressure. Always consult the manufacturer's performance curve and multiply your calculated capacity by the efficiency factor at your specific target pressure. 5. Summary Checklist for Verification

The core formula S = (V/t) * ln(P1/P2) will produce the effective pumping speed required at the chamber inlet.

| Load Type | Formula | Calculated Value | Unit | |-----------|---------|------------------|------| | Leak load | =Q_leak | 0.05 | mbar·L/s | | Outgassing load | =q_outgas * A_surface | 0.005 | mbar·L/s | | Process gas load | =Q_process | 0.02 | mbar·L/s | | | =SUM(above) | 0.075 | mbar·L/s |