A7™ Operating Instructions 046-004667-00 8 - 9
AG and O2 Concentration Monitoring Measurement Limitations
8.8 Measurement Limitations
Measurement accuracy may degrade due to:
• Leakage or internal leakage of the sample gas
• Mechanical shock
• Humidity or condensate
• Cyclic pressure which is greater than 10 kPa (100 cmH
2
O)
• Other interference source (if available)
NOTE: Gas data is reported as zero if the measured concentration is below the
defined threshold level during more than 3 s: CO
2
- 0.1/0.3%; N
2
O - 3/
3%; O
2
- 0/0%, Agents - 0.15/0.3% (Full/ISO accuracy).
NOTE: Inaccuracy is specified at 10-55 °C operating temperature and default
compensated for an H
2
O partial pressure of 11 mBar (i e 22 °C @40% RH
ambient conditions) and using a DRYLINE
TM
sampling system. Any
other ambient H
2
O partial pressure will dilute the gas sample to a
different extent, causing a measurement error. Under typical operating
conditions this effect is negligible. An increase of the ambient H
2
O
partial pressure to 30 mBar (i e 28 °C @80% RH or 33 °C @60% RH) will
cause a general error for all measured gases of -2%
REL
. For automatic
compensation of the ambient humidity effect on the gas sample
composition, the actual ambient H
2
O partial pressure can be input to
AION
TM
from the host via the communication interface.
8.9 Troubleshooting
If the gas inlet (including watertrap, sampling tube and airway adapter) is occluded by condensed
water, airway occlusion will be prompted on the screen.
To remove the occlusion:
• Check the airway adapter for occlusion and replace if necessary.
• Check the sampling tube for occlusion or kinking and replace if necessary.
• Check the watertrap for water build-up. Empty the watertrap. If necessary, replace the watertrap.
If that does not resolve it, internal occlusions may exist. Contact your service personnel.
If the expired O
2
concentration is higher than the inspired O
2
concentration, it is possible that the
pump rate is too low. Setting Gas Bench Flow Rate to High is recommended.