Theory of operation
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10070389 Rev. A
Puritan Bennett™ 700 Series Ventilator System Service Manual
2.2.2.2 Operational description of piston/cylinder system
During piston retraction, the piston draws air and/or oxygen into the cylinder through the
opened inlet check valve. The optical encoder (part of the motor/encoder) reports to the
motor controller circuit the motor shaft position. The motor controller circuit, in turn,
determines the piston position and velocity. The retraction velocity is controlled to draw in
150 L/min nominal. Gas behind the piston (mostly room air) is vented through the air intake
filter to atmosphere.
During gas delivery, the motor drives the piston forward as required to meet the ventilator
settings and patient effort. The gas flows through the opened outlet check valve and the
inspiration manifold toward the patient.
At power on, POST verifies the piston’s return, home, and full-stroke positions (Section 2.6.1).
For a complete, sequential description of breath delivery, see Section 2.6.
Summary of Contents for Puritan Bennett 700 Series
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