Chapter 3
3-6
Esprit® Ventilator Service Manual © Respironics, Inc.
REF 580-1000-02 G
Theory of Operation
Safety Valve (SV)
The safety valve contains a spring-loaded diaphragm that is controlled
by safety valve pilot solenoid (SOL 2). Under normal conditions SV is
closed, allowing delivered flow to reach the patient. In the event of a
safety valve open (SVO) condition, pilot pressure is vented to
atmosphere, which opens SV and allows the patient to breathe room air
through the safety port at the rear of the ventilator.
Air System Check
Valve (CV2)
The air system check valve (CV2) prevents oxygen from entering the air
delivery system in the event of a blower failure.
Inspiratory Non-
rebreathing Check
Valve (CV3)
The inspiratory non-rebreathing check valve prevents the patient from
exhaling through the inspiratory limb during a safety valve open
condition, which prevents the patient from rebreathing exhaled gas.
Pressure Relief Valve
(PRV)
The pressure relief valve provides a backup to the operator adjustable
high-pressure alarm and prevents excessive pressures in the patient
circuit. The PRV is spring-loaded to limit the maximum circuit pressure
to 130 to 140 cmH2O.
Oxygen Sensor (OS)
The oxygen sensor is an optional device that can be installed between
the 22-mm inspiratory port and the inspiratory bacteria filter. The
oxygen sensor is a galvanic device that measures the oxygen
concentration of the blended gas as it leaves the inspiratory manifold.
The output signal from the sensor is used for the high and low oxygen
concentration alarms. When the sensor is installed and calibrated, the
ventilator alarms if the measured oxygen concentration is not within 6%
of the %O
2
setting.
Inspiratory Pressure
Transducer (PT3)
The inspiratory pressure transducer on the sensor PCB monitors system
pressure from the inspiratory side of the patient circuit during
exhalation pressure transducer autozeroing, ensuring uninterrupted
pressure monitoring. It is also used with the exhalation pressure
transducer to detect patient circuit occlusions.
Delivery System Components
