Link the final required speed to standard pump sizes (e.g., Fieldpiece 5-CFM or 10-CFM models for HVAC use).
Sreal=Seff1+SeffCcap S sub real end-sub equals the fraction with numerator cap S sub eff end-sub and denominator 1 plus the fraction with numerator cap S sub eff end-sub and denominator cap C end-fraction end-fraction
The "pumping speed" at the pump inlet is rarely the same as the "effective speed" at the chamber due to pipe resistance. The formula for actual speed at the pump is:
Use the LN() function in Excel for the natural logarithm part of the capacity formula.
Where is the conductance of the piping system, which can be estimated using Excel calculators for conductance . Steps to Build Your Vacuum XLS Input Section: Create cells for Initial Pressure ( P1cap P sub 1 ), Final Pressure ( P2cap P sub 2 ), Volume ( ), and Time (
