Principles of operation
142 Instructions for use Carina SW 3.2n
Pneumatic function description
Functional units
1 Air inlet
2 Turbine
3 Measuring unit
4 Expiratory valve
5 Leakage valve
6 Oxygen dosing unit
7 Oxygen measuring unit
8 Oxygen port LPO
9 Oxygen port HPO
The ambient air passes through the inlet filter
(HEPA filter) (F1) and is compressed in the turbine
(2). The pressure depends on the processor-con-
trolled turbine speed. The low mass of the turbine
impeller allows fast speed changes and high flow
dynamics. The compressed air is sent to the meas-
uring unit (3) through a venturi (R2). The pressure
differential generated there is measured by the flow
sensor (DPS1) and used to regulate the flow.
The measured values of the first pressure sensor
(PS1) and the second pressure sensor (PS2) are
used to control the ventilation pressure. The calcu-
lation includes: specified setting values, ventilation
algorithms and characteristics of the original
Dräger breathing hoses (pressure loss by flow re-
sistance). Volume losses and pressure losses of
unknown components (third-party manufacturers)
cannot be taken into account (see "Volume losses
during ventilation" on page 144) and must be com-
pensated by manual adjustment of the ventilation
parameters. The leakage flow is continuously cal-
culated from the flow and pressure values. The tidal
volume is maintained at a constant level. During ex-
piration the turbine supplies a slight counter-pres-
sure for establishment of the defined PEEP.
The breathing gas temperature is monitored by the
sensors (AT1 and AT2). Increases in temperature
trigger an alarm message.
The connected breathing circuit (with controlled ex-
piratory valve or leakage valve) is defined at the
switch valve (V1) in the measuring unit (3).
113
HPO
control
board
Sensor
board
6
7
3
Patient
Motor
blower
1
CV1
F1
CV2
pilot line for exp. valve
4
CV4
5
R1
(e.g. Silent
Flow)
CV3
Inlet
labyrinth
Outlet
labyrinth
8
PS1
E
p
PS2
E
p
DPS1
R2
E
Δp
AT2
EV
LV
AT1
V2V3
F3
V5
F6
F5
9
R4
DPS3
E
Δp
CV6
CV8
V6
V7
CV9
2
V1
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