# Pressure and gas flow for optimization

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A PI controller delivers the best results for a certain working point (pressure/gas flow). If there is only one working point, this pressure and gas flow has to be used for optimizing P and I-Gain. If there are several working points that have to be covered, the pressure for optimizing is the medium pressure between highest and lowest pressure to be controlled, the gas flow for optimizing is the highest flow out of all working points.

Two different pressure set points are necessary for optimization.

Set point 1 (SP1) is the pressure for optimizing as determined above.

Set point 2 (SP2) is about 10 - 20% lower than SP1.

Example: pressure range: 4 – 10 Torr

Flow range: 2 – 4 slm

Pressure set points and gas flow for optimization:

SP1 = 7 Torr

SP2 = 6 Torr

Gas flow = 4 slm