A7™ Service Manual 046-006272-00 5 - 75
Repair and Troubleshooting Sensors and Valves Problems
5.4.7 Opening State of the Inspiratory Valve Problems
By using [Diagnostic Tests], you can detect if the opening state of the inspiratory valve is correct.
1. The methods for tube connections and settings of the anesthesia machine are the same as
those for sampling line connections of the flow sensors. For details, refer to ‘‘Preparations before
Using Diagnostic Tests’’ on page 5-72.
2. In the [Diagnostic Tests] menu, gradually increase the D/A value of the inspiratory valve. If the
measured values of the ventilator flow sensor, inspiratory flow sensor, and expiratory flow sensor
change very little and low gas flow is felt at the connector of water collection cup, it indicates
that the inspiratory valve or the D/A on the Ventilator Control Board is defective.
3. Normally, when the D/A value of the inspiratory valve is set to “2500”, the flow measured by the
standard flow measurement device can reach 90 L/min.
4. If when the D/A value of the inspiratory valve is set to more than “4000”, the flow measured by
the standard flow measurement device fails to reach 90 L/min, flow calibration will fail. In this
case, you need to replace the expiratory valve assembly or the ventilator control board.
5. To locate if the DA on the Ventilator Control Board is defective, you can use a multimeter to
measure the output of DA on the Ventilator Control Board corresponding to the inspiratory
valve. If voltage also increases with the increase of D/A value, and voltage nears 6V when D/A
value is set to more than “4000”, it indicates that the DA on the Ventilator Control Board
corresponding to the inspiratory valve may be correct.
6. After the expiratory valve assembly or the Ventilator Control Board is replaced, you can use the
similar method to check if the problem is fixed.
5.4.8 Opening States of the PEEP Safety Valve Problems
When the PEEP safety valve is permanently OFF and the gas supplies are within specifications, the
[Drive Gas Pressure Low] is alarmed.
By using Diagnostic Tests, you can detect if the opening states of the PEEP safety valve and PEEP valve
are correct.
To diagnose the opening state of the PEEP safety valve:
1. Make sure that gas supplies are within specifications.
2. In the [Diagnostic Tests] menu, when the PEEP safety valve is switched on, a subtle click is heard.
3. Adjust the D/A value of the PEEP valve to cause the pressure measured by the PEEP pressure
sensor to exceed 0 cmH2O.
4. Switch off the PEEP safety valve. The pressure measured by the PEEP pressure sensor should
drop to 0 cmH2O immediately. Switch on the PEEP safety valve again. The measured value of the
PEEP pressure sensor rapidly restores almost the same value to that before PEEP safety valve is
switched off. During this period, gas flow and also change of gas flow when the PEEP safety
valve is switched on or off can be felt at the PEEP outlet, which helps to judge if the PEEP safety
valve can be switched on or off correctly.
5. If an error is detected, it is possible that the PEEP safety valve or the safety valve drive voltage on
the ventilator control board is defective. You can use a multimeter to measure the drive signals
on the ventilator control board corresponding to the PEEP safety valve (measurement can be
performed at the corresponding socket). When the PEEP safety valve is turned on, the drive
voltage should near 6V. When the PEEP safety valve is turned off, the drive voltage should near
0V. If these two conditions are met simultaneously, the ventilator control board is normal.
6. If the PEEP safety valve is defective, replace the expiratory valve assembly. After replacement,
you can use the similar method to check if the problem is fixed.
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