Dräger Medical Fabius Tiro Technical & Service Manual page 44

RETURN TO THIS MANUAL'S TABLE OF CONTENTS
RETURN TO CD-ROM TABLE OF CONTENTS
Fabius Tiro Function Description
Two diaphragms (upper and lower) comprise a bag-type rolling seal that sur-
rounds the piston. Vacuum from the pneumatic assembly (described in a later
paragraph) is provided between the outside of the seal and the cylinder, to
ensure proper operation of the seal during piston movement.
During inspiration the ventilator delivers fresh gas at a given volume, pres-
sure and frequency. These parameters are set at the control panel. Refer to
the Operatorís Manual for details on ventilator settings, displays and controls.
During expiration, the bag-type rolling seal fills with expired gas from the
patient and with fresh gas stored in the breathing bag.
Power for the ventilator motor is distributed from the control PCB. A position
sensor on the ventilator signals the control PCB when the piston reaches its
lower limit. An incremental encoder on the motor shaft determines the num-
ber of revolutions and provides piston travel information to the control PCB.
Ventilator pressure is monitored by a transducer on the control PCB. Should
the negative pressure relief valve on the patient assembly open, a Fresh Gas
Low alarm is displayed if enabled via service mode.
The ventilator pressure transducer is the same type as the one used for mea-
suring airway pressure. A hose connects the transducerís positive pressure
port to a hose barb located on the top cover of the ventilator. The purpose of
this transducer is to allow the software to sense when a condition exists that
would cause the ventilator negative pressure relief valve to open. The thresh-
old used by the software for this condition is -8 mbar. In normal use the pri-
mary cause for this condition is an insufficient amount of reserve gas in the
breathing bag. The operator is alerted when this condition exists, with a
medium priority FRESH GAS LOW alarm. This alarm may be disabled via
service mode.
The ventilator assembly is illustrated on Figure 28.
38
Dräger Medical AG & Co. KGaA 6020.002 Revision B Released