A7™ Service Manual 046-006272-00 5 - 73
Repair and Troubleshooting Sensors and Valves Problems
You can also detect the zero points of the sensors by referring to 3.7.3 Check the Sensor Zero Point.
NOTE: For the normal range of sensors’ zero points, refer to “Check the Sensor
Zero Point” on page 3-24.
5.4.5 Connections and Measurement of the Flow Sensors
Problems
The flow sensor has two sampling lines. Connection errors include:
• The two sampling lines are connected backward.
• One sampling line is not connected.
• Both sampling lines are not connected.
By using the Diagnostic Tests tool, you can detect if the sampling lines are connected correctly.
To diagnose the sampling line connection of the flow sensor:
1. Connect the tubes of the anesthesia machine following the constant-flow connection method.
Refer to “Preparations before Using Diagnostic Tests” on page 5-72.
2. Make sure that gas supplies are within specifications. In the [Diagnostic Tests], PEEP safety valve
to ON and the D/A value of the PEEP valve to more than “1500”, making sure that the PEEP valve
closes at above 30 cmH2O.
3. Increase the D/A value of the inspiratory valve gradually and the A/D value of the flow sensor
should also increase. With the gradual increase of gas supplied,
• If the A/D value of one sensor decreases gradually, it is possible that the two sampling lines
of the sensor are connected backward.
• If the A/D value of one sensor stays unchanged, it is possible that the two sampling lines of
the sensor are broken or not connected.
• If the A/D value of one sensor nears saturation (above “4000”) quickly, it is possible that the
sampling line at the low pressure end (gas outlet end) of the sensor is not connected.
4. If sampling line connection errors are detected, re-connect all sampling lines and verify proper
connection of lines.
To diagnose the measurement error of the flow sensors:
1. After confirming that both the zero points of the sensors and the sampling line connections of
the sensors are correct, check the flow sensor accuracy:
• With the gradual increase of actual flow, the measured value of the flow sensor should also
increase. Otherwise, the calibration data have errors. You need to calibrate the flow sensor
again.
• Compared with the measured value of the standard flow measurement device (anesthesia
machine calibration device), the measured value of the flow sensor should be accurate.
Otherwise, the calibration data have errors. You need to calibrate the flow sensor again.
For details, refer to “Check the Flow Sensor Accuracy” on page 3-25..
5.4.6 Connections and Measurement of the Pressure Sensors
Problems
The pressure sensor has one sampling line. Connection errors include:
• The sampling line is not connected.
• The sampling line is connected incorrectly.
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