Datex-Ohmeda Aestiva 7900 SmartVent, Service Manual

Page: 71 / 181

4/Tests and Troubleshooting
1503-0151-000 5/26/0 4-25
Calibrate Flow Sensors
See operation and maintenance manual.
The software calibrates the inspiratory flow, expiratory flow, airway pressure and
manifold pressure transducers for zero pressure offset voltage. It does so by read-
ing the A/D for inspiratory flow, expiratory flow, airway pressure and manifold pres-
sure when the flow sensors have been disconnected from the patient interface
panel. If the A/D values are not within the correct tolerance the calibration fails. If
the calibration passes, the A/D values at which the inspiratory flow, expiratory flow,
airway pressure and manifold pressure transducers were calibrated at are stored
in the EEPROM.
Remarks
Fail - indicates a problem with the microcontroller board, check for bad differential
pressure transducer. Check the transducer outputs using the Display A/D menu.
If the transducer is not zeroing, remove the exhalation valve from the manifold. If
the transducer zeros, replace the flow valve. If not, replace the microcontroller
board.