12-13 
 
12.10 Water Build-up in the Flow Sensor 
12.10.1 Prevent Water Build-up 
The patient’s exhaled warm and moist gas is condensed when it flows through the expiratory 
hose. The condensed water remains on the hose wall and finally enters the water trap. When 
the patient’s exhaled gas arrives at the expiration valve, condensed water may appear at the 
expiration valve (including the expiratory flow sensor), compromising the measurement 
accuracy of expiratory flow sensor. 
 
Check the expiration valve for water build-up when abnormal flow waveform or unstable 
tidal volume fluctuation is detected. If there is water build-up inside the expiration valve, 
clear it before use. 
 
Check the expiratory water trap for water during the use of the ventilator. If there is water 
build-up, empty it promptly. Water condensation in the expiration valve can be reduced by 
using a bacteria filter between the expiratory tube and expiration valve. 
 
12.10.2 Clear Water Build-up 
If there is water built up inside the expiration valve, remove the expiration valve and clear the 
water. Then reinstall the valve for use. 
 
 
WARNING 
  Ensure that all breathing system parts are dry every time when the breathing 
system is cleaned and disinfected. 
  Check the expiration valve for water build-up when abnormal flow waveform or 
unstable tidal volume fluctuation is detected. If there is water build-up inside the 
expiration valve, clear it.