Mindray WATO EX-55, Service Manual

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2.2.4.4 Breathing System
The breathing system provides a closed loop for the anesthetic gas. The CO2 in the patient’s
expired gas can be inspired in the inspiration phase to maintain the temperature and humidity
conditions of the patient’s expired gas. During inspiration, the drive gas depresses the bag
inside the bellows to force the inside gas to enter the patient’s lung. During expiration, the
patient’s expired gas goes into the bag inside the bellows. Sodalime canister 34 absorbs CO2
the patient expires. The following figure shows the pneumatic circuit of breathing system.
Manual and mechanical ventilation modes are selected through the bag/mechanical
ventilation switch. When manual ventilation is selected, the doctor presses manual bag 42 to
supply gas for the breathing system. APL valve 43 is used to adjust the pressure inside the
pneumatic circuit in case of manual ventilation. When mechanical ventilation is selected, the
ventilator starts to work. It controls the drive gas to depress the folding bag inside bellows 45
and supply gas for the breathing system as per the selected ventilation mode.