pumping speed


The basic definition of the pumping speed is given here.

Here we calculate the reduction of the pumping speed for a pump that is connected to a vacuum system via a tube of conductance C. In the section on conductance, we have seen that the conductance of two elements with conductance C1 and C2 in series gives a total conductance C of

This equation can also be used to calculate the reduction of pumping speed S to an effective pumping speed Seff when the pump is connected to the system through a tube of conductance C, giving

For the design of the vacuum system, it is thus sensible to connect the pumps through straight and wide tubes that have a high conductance. When such connections are not possible, it is a good idea to calculate how the transmission of the tubes affects the effective pumping speed, so that a pump with sensible performance can be used.


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