Service manual
68 Siemens-Elema AB E382 E380E 061 01 03 01
Description of functions Servo Ventilator 300/300A
2
11 Inspiratory channel
The fresh gas from the INSPIRATORY VALVES (8
and 9) is mixed and lead to the patient
system via this channel. The O
2
cell and the
safety valve are also parts of the inspiratory
channel.
11.1 Inspiratory mixing part
The different fresh gases come together in
this part. It also contains a fitting which
connects to the main block 12 INSPIRATORY
PRESSURE
.
The INSPIRATORY MIXING PART is designed to
suppress pressure oscillates from going to
the pressure transducer.
11.2 Inspiratory pipe
This plastic pipe leads the mixed gas from
the 11.1 INSPIRATORY MIXING PART to the patient
system. It is held in position by a snap lock.
It contains a holder for the 11.3 O
2
CELL and it
is integrated with the 11.4 SAFETY VALVE seat.
The outlet of this inspiratory pipe is called
INSPIRATORY OUTLET.
11.3 O
2
cell
The O
2
cell is mounted in a holder on the
11.2 INSPIRATORY PIPE and protected by a
bacteria filter. Service interval 3000 h of
operation for exchange of the O
2
BACTERIA
FILTER
.
The O
2
cell gives an output voltage
proportional to the partial pressure of oxygen
inside the INSPIRATORY PIPE. At constant
pressure this output is proportional to the O
2
concentration in percent. In each O
2
cell the
output signal will stay at a fairly constant
level usually within 1017 mV in normal air
and standard barometric pressure during the
life time of the cell. This signal is used in the
block 15.3 O
2
CONCENTRATION AMPLIFIER. The cell
should be replaced when the output level
has started to decrease. In this situation,
repeated calibration of the O
2
concentration is
required.
The life time of the cell is affected by the O
2
concentration. With the O
2
concentration (at
the cell) in % and expected cell life in hours
the following applies at 25°C (77°F):
O
2
concentration x Expected cell life N
800 000% hours.
A separate output signal (O
2
CELL CONNECTED L)
indicates if the O
2
cell is connected or not.
This signal is used in the main block 4
MONITORING. The O
2
cell cable is connected to
the board PC 1607 PNEUMATIC INTERCONNECTION
(connector P22) inside the PATIENT UNIT.