Ventilator Pneumatic- O2 Drive Gas Theory of Operation
1 - 72 046-001141-00 A5/A3™ Service Manual
1.8 Ventilator Pneumatic- O2 Drive Gas
1.8.1 Ventilator Pneumatic Drive
Oxygen is the driving gas for the ventilator. In addition to the flow meter block, a high pressure
regulator reduces the supply pressure to 200 kPa (29 psi). This pressure represents the drive gas for
the ventilator.
The drive pressure regulator is placed ahead of the proportional valve that generates the driving gas
flow during the inspiratory phase. This flow fills the bellows dome that surrounds the bellows.
1.8.2 Drive Pressure-High Pressure Regulator (200 kPa, 29 psi)
The drive pressure regulator stabilizes the supply pressure provided to the proportional valve. The
flow generated by the proportional valve is therefore independent of pressure variations at the
supply.
Setting the drive pressure regulator at 200 kPa (29 psi) allows for a maximum inspiratory flow of 110
L/min at the ventilator.
1.8.3 Drive Gas Assembly
The manifold assembly module mainly consists of the inspiratory circuit and PEEP circuit. The
inspiratory circuit goes through the normally closed proportional solenoid valve, which generates a
gas flow of 0 to 110 L/min by the valve drive board. The gas flow of the PEEP circuit goes through the
normally closed proportional solenoid valve, which also generates a gas pressure of 3 to 30 cmH2O
by the valve drive board.
1.8.4 Tube Color Coding
All the pneumatic tubes used in the anesthesia system are color coded for use in the United States
only.
GAS US STANDARD
O2 GREEN
N2O BLUE
AIR ORANGE
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