CareFusion MicroRPM Manuel D'utilisation page 44

If adjustment is required then the following procedure must be
followed.
The calibration may only be adjusted in a positive direction as the
meter monitors the peak pressure value. Therefore if the respiratory
pressure meter reading was greater than the manometer reading the
calibration screw must be turned anti-clockwise a few turns before
calibration is attempted.
S e r i a l
p o r t
C a l i b r a t i o n
s c r e w
Connect the respiratory pressure meter to the manometer as
previously shown. Fill the syringe to obtain the required negative
pressure and then turn the calibration screw slowly in a clockwise
direction until the same value is displayed on the meter.
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