Mindray WATO EX-55Pro, Service Manual

Page: 66 / 474

2-52
2.2.4.2 Electronic Flow Control System-EFCS
The EFCS uses solenoid proportional valves to control the oxygen, air and nitrous oxide flow and
monitor the actual flow, and provides feedback to the flow control unit. After passing three
independent check valves, the gases of the three limbs are mixed at the rear end of the assembly
and output. The O2-N2O ratio is fully controlled by a software algorithm. The system display
outputs the monitored values of parameters such as the limb flow and O2-N2O ratio.
The above figure shows the pneumatic block structure of the EFCS. The three gases, after being
regulated, goes through the proportional valves, through limb sensors, through the gas mixing
chamber, and into the three-way valve. Then, the gas mixture returns to the total flow sensor and
finally output to the mechanical float flow meter.
O2 (from the
O2 supply) N2O (from
the N2O
supply)
Air (from the
air supply)
From
backup O2
flowmeter
To the
vaporizer
manifold
Balance gas
sensor
O2 sensor
Total flow
sensor