That means the 7100 ventilator does not look at the actual pressure and adjust for errors. Pressure is achieved by opening the flow valve 30 cmH2O and the setting the PEEP valve to the value should achieve the set pressure. The PEEP valve setting determined during PEEP valve calibration. It is effected by the accuracy of the Airway Sensor. Hence, the recommendation is to always first calibrate the Airway Span prior to calibrating the PEEP valve. The PEEP establishes power requirements at different points, then calculates the other points as a linear curve.