Mindray A9 - Pressure and Flow Zeroing (Service)

6-43
Failure
Description
Possible Cause Recommended Action
Display 39 The system fails to write data into
EEPROM.
1. Perform the calibration again.
2. Replace the VCM.
6.3.7 Pressure and Flow Zeroing (Service)
6.3.7.1 Principles
The anesthesia machine automatically performs pressure and flow zeroing at regular intervals
during operation. You can also perform pressure and flow zeroing manually in the factory
maintenance menu. Manual zeroing can immediately eliminate measurement deviations caused
by zero offset of sensors. The anesthesia machine supports automatic and periodic pressure and
flow zeroing. The first four zeroing operations are done automatically 5, 15, 30, and 60 minutes
after ventilation starts. Then automatic zeroing takes place every 120 minutes. The three-way
valve is opened and closed for valve flushing during mechanical ventilation and before automatic
zeroing. A dent appears in the waveform during zeroing, or opening and closing of the three-way
valve.
The zeroing principles are as follows: During manual zeroing in standby mode, the VCM closes
the inspiratory valve and PEEP valve, and opens the three-way valve to start zeroing. The VCM
collects the pressures or flow AD values of the Paw sensor, PEEP sensor, inspiratory flow sensor,
expiratory flow sensor, and built-in flow sensor, and uses them as the AD values of the sensors at
zero point. It closes the three-way valve, and the zeroing ends. The VPM is instructed to
synchronize zeroing during manual zeroing in standby mode.
Processing in manual zeroing is the same as that in automatic zeroing during ventilation. The
opening and closing of the three-way valve are controlled to zero the Paw sensor, inspiratory flow
sensor, and expiratory flow sensor. After zeroing is enabled, the three-way valve is opened for
zeroing, the pressure or flow AD value of each sensor is collected and used as the AD value of
each sensor at zero point. Then the three-way valve is closed, and the zeroing ends.