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Blower
Flow
valve
Air flow
sensor
Diffuser
REF 1029568 Rev B
3.1.3
Blower
The blower consists of a speed-controlled DC motor coupled to a single stage
impeller. The motor speed is monitored and adjusted by the controller PCB
based on patient settings. A pressure tap at the blower outlet enables
monitoring and comparison with the proximal (patient) pressure.
3.1.4
Flow Valve
The flow valve is a mechanical sliding assembly driven by an electromagnetic
coil. Valve commands from the controller PCB control current (-125 to
675 mA) to the coil. Flow valve movement is proportional to the current
through the coil. The flow valve operates as a closed-loop system, using
feedback from the flow sensor and pressure transducers.
3.1.5
Air Flow Sensor
The air flow sensor measures flow from the flow valve. The ventilator uses this
measurement to provide closed loop control of the flow valve to interpret
patient demand and calculated leak rate.
3.1.6
Diffuser
The diffuser is located on the output of the flow valve and is designed to
provide a reduction of air turbulence.
BiPAP Focus Ventilator Service Manual © Respironics, Inc.
Chapter 3
Theory of Operation
3-3
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