Mindray WATO EX-55Pro, Service Manual

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2-62
The following figure shows the pneumatic circuit diagram of the pneumatically-controlled module
of anesthetic ventilator.
As shown in the above figure, in the drive gas limb, the filter 9 filters drive gas again. The
regulator 10 regulates pressure (about 0.2 MPa) inside the pneumatic circuit. The proportional
solenoid valve 11 controls thedrive gas flow. The drive gas goes through the flow sensor 12 of
differential pressure type that monitors drive gas flow. The mechanical overpressure valve 13
ensures that the pressure in the drive gas circuit does not exceed the safety pressure. It releases
excess gas when gas pressure exceeds 11 kPa (110 cm H2O). The drive gas enters the bellow
through the exhalation valve 18. During expiration, the drive gas in the bellow goes out through
theis valve.
In PPEP limb, the PEEP function is performed through the expiratory valve. When PPEP valve 17
opens, gas is bled from the pneumatic resistor 19, forming relatively stable pressure in the
pneumatic circuit from PEEP valve 17 to the pneumatic resistor 19. Such pressure is exerted on
the membrane of the expiratory valve 18 to form PEEP.
To prevent excessively high pressure inside the pneumatic circuit from injuring the patient and
damaging the equipment, the pressure relief valve 15, which is a solenoid on-off valve, is placed
before the gas pathway of the expiratory valve. When the drive gas pressure is less than 125 kPa,
an alarm is triggered by the pressure switch 16. The pressure sensor 48 monitors the pressure at
the expiratory valve which is closed. The mechanical pressure relief valve 51 ensures that the tube
pressure after the expiratory valve is less than 10 cm H2O in expiration phase.
2.2.7 Anesthetic Gas Scavenging System
The AGSS is composed of the AGSS transfer system, the AGSS receiving system, and the AGSS
disposal system. Waste gas goes from the exhaust port of the anesthesia machine through the
AGSS transfer system and the AGSS receiving system to the hospital's waste gas disposal system
(AGSS disposal system), as shown in the following figure.
The following diagram shows the operational theory of the AGSS. The throttling holes reduce the
effect of negative pressure at the AGSS outlet onto the flow at the entrance. The float helps the
user to learn if the AGSS works normally. When the upper edge of the float is between the MAX
and MIN marks of the sight glass, it indicates that the AGSS is in normal working status. The filter
filters foreign substance to prevent the disposal system from being occluded. The gas reservoir is
connected to the air through pressure compensation openings. When positive or negative pressure
occurs inside the gas reservoir, gas is inputted or outputted to ensure pressure balance inside the
system.
Drive gas
Enter the bellow
assembly
Enter gas reservoir