A- System Components; Supply Gas Inlet Filter; Supply Pressure Sensing Switch; Airway Pressure Transducer - BIO-MED DEVICES CROSSVENT-3+ Operation & Service Manual

VIII THEORY OF OPERATION- cont'd.
A A A A - - - - SYSTEM COMPONENTS SYSTEM COMPONENTS
SYSTEM COMPONENTS SYSTEM COMPONENTS
S U P P L Y G A S I N L E T F I L S U P P L Y G A S I N L E T F I L T E R S U P P L Y G A S I N L E T F I L S U P P L Y G A S I N L E T F I L
The supply gas passes through an inlet filter that is located inside the supply gas fitting on the right side of
the ventilator. This filter should be changed periodically as required.
microns. If equipped with entrainment, there is a second filter in the venturi assembly at the inlet in the
rear of the unit.
NOTE: It is recommended that an external filter/water trap be used on the supply gas at all times in order to
provide greater protection to the internal components of the Crossvent.
S U P P L Y P R E S S U R E S E N S S U P P L Y P R E S S U R E S E N S I N G S W I T C H
S U P P L Y P R E S S U R E S E N S S U P P L Y P R E S S U R E S E N S
A pressure sensitive switch is installed on the gas supply side of the internal pressure regulator. Should the
gas supply pressure to the ventilator drop to a predetermined level, an audible and as well as visual alarm
will occur.
A I R W A Y P R E S S U R E T R A N S D U C E R A I R W A Y P R E S S U R E T R A N A I R W A Y P R E S S U R E T R A N A I R W A Y P R E S S U R E T R A N
This connects to the proximal airway tube on the circuit through the fitting on the side of the unit. The
pressure transducer converts the pressure signal into an electrical signal.
represents the pressure waveform is then used by the CROSSVENT's microprocessors to accomplish a
multitude of tasks. It is used to sense a pressure drop in the patient breathing circuit created by an
inspiratory effort and then provide a trigger signal to initiate inspiration.
establishes the levels for the all of the pressure related alarms.
D I F F E R E N T I A L P R E S S U R E T R A N S D U C E R D I F F E R E N T I A L P R E S S U R
D I F F E R E N T I A L P R E S S U R D I F F E R E N T I A L P R E S S U R
This component is only present if the unit has the optional Exhaled Tidal Volume monitoring feature
installed. It is utilized to measure the pressure drop across an orifice in a pneumotachograph. The
pneumotach (flow sensor) is placed at the proximal airway. As exhaled gas passes through the orifice, it
creates a pressure drop from one side of the orifice to the other. This highly sensitive differential pressure
transducer measures this small pressure difference. The signal from the transducer is then converted by the
microprocessors into a measurement of exhaled tidal volume and minute volume.
M A X I M U M P R E S S U R E R E L I E F V A L V E M A X I M U M P R E S S U R E R E L M A X I M U M P R E S S U R E R E L M A X I M U M P R E S S U R E R E L
This valve vents gas to atmosphere whenever the pressure in the breathing circuit exceeds the preset level of
120 cmH O.
2
D I A P H R A G M A C T D I A P H R A G M A C T D I A P H R A G M A C T U A T E D R E L I E F V A L V E ( D I A P H R A G M A C T U A T E D R E L I E F V A L V E ( D . A . R . V . ) U A T E D R E L I E F V A L V E ( U A T E D R E L I E F V A L V E (
This is controlled by the output signal from the Maximum Pressure needle valve (front panel), which is also
applied to the exhalation valve. It sets the relief pressure at approximately the same level as the exhalation
valve.
N E G A T I V E P R E S S U R E R E N E G A T I V E P R E S S U R E R E L I E F V A L V E N E G A T I V E P R E S S U R E R E N E G A T I V E P R E S S U R E R E
This allows gas to enter the breathing circuit whenever a negative pressure greater than approximately 4-5
cmH O is generated. This acts as a failsafe mechanism and in the event of a total system power failure
2
allows the patient to inhale ambient air.
WARNING: Breathing through this valve requires a greatly increased work of
breathing and only air is provided. A situation in which the patient is breathing
through this valve should be rectified immediately in order to prevent possible
adverse affects to the patient.
WARNING: Should the use of the negative pressure relief valve become necessary,
the operation of the Crossvent in a contaminated environment can be hazardous.
T E R T E R T E R
I N G S W I T C H
I N G S W I T C H I N G S W I T C H
S D U C E R S D U C E R S D U C E R
E T R A N S D U C E R
E T R A N S D U C E R E T R A N S D U C E R
I E F V A L V E I E F V A L V E I E F V A L V E
D . A . R . V . ) D . A . R . V . ) D . A . R . V . )
L I E F V A L V E L I E F V A L V E L I E F V A L V E
It filters particles down to 40
This electrical signal, which
The transducer output also
36 36 36 36