Vacuum Pump Capacity Calculation Xls Repack Online

"It's not just about the pump being 'big enough'," Elias concluded. "It's about the balance between the vessel volume, the air leaks, the water temperature, and the seal water temperature. Your spreadsheet tells us that this rusty 600 m3 pump can do the job, provided we don't have a sudden gasket blowout and we throttle the inlet to manage the flash steam."

Vacuum pump capacity is expressed as Volumetric Flow Rate or Pumping Speed (

This approach is useful for initial screening but should be confirmed with detailed calculations for final design.

[ t = \fracVS \cdot \ln\left(\fracP_1P_2\right) ] vacuum pump capacity calculation xls

Assume:

Create a second sheet, Evac_Curve , to solve for time to reach each pressure:

| | Description / Formula | Type | |-----------------|---------------------------|----------| | B3 | System Volume (m³) | User Input | | B4 | Initial Pressure (mbar) | User Input (typically 1013) | | B5 | Final Pressure (mbar) | User Input | | B6 | Desired Pump-down Time (hr) | User Input | | B7 | Leakage Rate (m³/hr) | User Input or Calculated | | B8 | Outgassing Load (m³/hr) | Calculated | | B9 | Pump Speed (S) | =B3/B6*LN(B4/B5)+B7+B8 | | B10 | Required Pump Capacity (S) | =B9 (Result) | "It's not just about the pump being 'big

is essential for reliable system performance and energy efficiency. While the underlying mathematics—Gaede's equation, conductance formulas, and outgassing rates—can be complex, a well-designed Excel spreadsheet simplifies the process by:

Before opening Excel, you must understand the governing equation. The fundamental relationship for evacuating a closed volume under ideal conditions (no leaks, no outgassing) is given by:

A professional-grade calculator typically includes: [ t = \fracVS \cdot \ln\left(\fracP_1P_2\right) ] Assume:

trapped inside the vessel (Pull-down load).

| | Consequence | |-------------|-----------------| | Ignoring outgassing | Pump under-sized; system fails to reach target pressure | | Forgetting conductance losses | Effective speed much lower than pump's rated speed; extended pump-down time | | Using average pump speed across all pressures | Pump speed varies with pressure; accuracy suffers | | Neglecting leak rate at operating pressure | Leakage rates vary with pressure; use the rate at the final pressure | | Overlooking water vapor load | Pumps not designed for vapor may require gas ballasting | | Incorrect unit conversions | Significant calculation errors |

=(Total_Volume_Cell / (Time_Cell / 60)) * LN(Pressure_Ratio_Cell)