User's Manual Part 3
10-21
7.
Verify the gas readings
Notes:
If the calibration process fails, the flag SPAN_ERR is set, and will stay
active until the next successful calibration is passed.
As long as no sampling line is connected, an ISA gas analyzer stays in a low-power,
sleep mode. Once the sampling line is connected, the ISA gas analyzer switches to
measuring mode and starts delivering gas data.
E.2.4.
Zeroing ยท
The infrared gas analyzer needs to establish a zero reference level for the CO
2
,
N
2
0
and
anesthetic agent gas measurement. This zero calibration is here referred to as
"Zeroing".
ISA sidestream gas analyzers perform Zeroing automatically by switching the gas
sampling from the respiratory circuit to ambient air. The automatic Zeroing takes less
than 3 seconds for ISA CO2 gas analyzers and less than 10 seconds for ISA multigas
analyzers. If the ISA sidestream gas analyzer is fitted with an oxygen sensor, the
automatic Zeroing will also include room air calibration of the oxygen sensor. Since a
successful Zeroing requires the presence of ambient
air (21% O
2
and 0% CO
2
) ,
ensure
that the ISA is placed in a well-ventilated place.
During
Zeroing,
if
J
SA
'
s
exhaust
gas
is
returned
to
the
patient
circuit
,
the returned gas
level
will
be different from the gas level at the sampling site
ISA OR+ Multigas
analyzers normally perform Zeroing directly at startup (with or
without Nomoline attached), when a steady operating temperature is achieved and
thereafter
every
8 h from start up. A Zeroing is also performed when the operating mode
is changed from sleep mode to measurement mode.
Additional automatic Zeroing can however be performed if the system consider it
necessary.
E.2.5.
Flow reference zeroing
Addition to the Zeroing the ISA sidestream gas analyzer also perform an automatic flow
reference zeroing
1
h from startup and thereafter
every
96h. During a flow reference
zeroing the ISA sidestream gas analyzers switch from gas sampling from the respiratory
circuit to ambient air while the pump is switched off. Hence no flow will be drawn from the
reference inlet. During the automatic flow reference zeroing , which takes less than 8
seconds , the LEGI will be blinking with a green light.