Compact Airway modules
Document No. 800 1009-1
39
4.2
Gas sampling system troubleshooting
The faults which can occur in the sampling system are: leaks or blockages in the tubing, failure of
the sampling pump or the magnetic valves, or diminishing of the flow rates because of dirt
accumulating in the internal tubing.
The following checks should help in localizing the fault. Whenever suspecting the sampling system
and always after having done any work on the sampling system check and if necessary adjust the
flow rate.
CAUTION
The special internal sample tube is mechanically fragile. Sharp bends will cause
leaks.
NOTE: D-fend water trap should be replaced when the REPLACE D-FEND message appears during
the monitor startup.
NOTE: If any liquid has entered the TPX measuring unit due to water trap filter failure, contact
Datex-Ohmeda Technical Services.
4.2.1
Sampling system leak test
1.
Prevent the module from performing the normal occlusion functions, i.e. controlling the
valves, by turning the pump first off, then on again from the menu.
2.
Block the reference gas connector at the front panel.
3.
Connect a flow cassette with high flow resistance value (50/1.1) to the end of the sampling
line and start following the ‘Amb-Work’ -value in the service menu. When the value exceeds
170 mmHg connect the other port of the flow cassette to the sample gas out connector and
switch the pump off.
4.
Wait until pressure inside the sampling system is stabilized then notice the shown ‘Amb-
Work’ -value. The value, i.e. the pressure inside the sampling system should not drop more
than 6 mmHg in one minute.
5.
If the pressure drops more, first ensure the connections you have made and repeat the test.
4.2.2
Steam test for the Nafion
TM
tubes
Choose Halothane as anesthetic agent and let the monitor sample room air. Then quickly feed air
of 100 % relative humidity (for instance from a kettle in which you are boiling water) to the monitor.
If the digital reading jumps as much as 0.1 % replace the Nafion tubes.
