Page D-2 LTV
®
Series ventilator Operator’s Manual
p/n 10664, Rev. Y
Ventilation flow enters the Flow Valve, which controls all inspiratory gas flow to the patient. The valve
is driven by a rotary actuator, and translates circular motion to a poppet position, which in turn meters
flow to the patient. The valve is characterized such that gas flow is a known function of differential
pressure across the valve and actuator position. A Differential Pressure Transducer is provided to
measure the differential flow valve pressure.
Ventilation gas exiting the Flow Valve is connected to the Exhalation Valve by a patient circuit. The
Exhalation Valve provides the following functions:
1) Closes the exhalation port during inspiration to divert gas to the patient.
2) Opens the exhalation port during exhalation to allow patient gases to be exhausted to the
atmosphere.
3) Provides variable PEEP (Positive End Expiratory Pressure) during the exhalation phase.
4) Measures the exhaled flow using a fixed orifice type transducer. Transducer sensor ports are
located between the patient and ventilator connection ports.
A Differential Pressure Transducer is provided to measure the delta pressure developed across the
flow transducer at the patient wye. This transducer also monitors volume and flow to trigger alarms.
The transducer is autozeroed to ambient pressure and the sense lines are purged to prevent moisture
migration into the transducer.
The Oxygen Blender accepts pressurized oxygen from an external source and as directed by the
control system meters the oxygen flow to meet the requirements of the current O
2
% setting and
ventilation flow demand. The O
2
Pressure Transducer measures inlet pressure and is used by the
blender control system to compensate the oxygen delivery for variations in oxygen inlet pressure.
The Sub-Ambient Relief Valve allows the patient to inspire spontaneously from room air in the event
of a failure of the main ventilator system. The Over Pressure Relief Valve provides an independent
mechanical means to limit the maximum inspiratory pressure. Both of these functions are physically
included in the Flow Valve Body.
The Airway Pressure Transducer measures pressure at the patient airway and is used for a
feedback signal during the delivery of pressure breaths. This transducer also monitors airway
pressure to trigger alarms. The transducer is autozeroed to ambient pressure and the sense lines are
purged to prevent moisture migration into the transducer.
To Next Page
Loading...
