3-22 
3  Blow to the CO
2
 sensor to generate a CO
2
 waveform and then place the sensor in the air. 
Check if the alarm message [CO
2
 Apnea] is displayed on the screen. 
4  Connect the test system as follows 
 
 
 
Indication of numbers in the figure above 
 
1  A steel gas cylinder with 6±0.05% CO
2
 
2 Flowmeter 
3  3-way valve (power supply controlled) 
4  Open to air 
5  Power supply   (controlling two 3-way valves) 
6  Compressed air or N
2
 with standard concentration 
7 Mainstream CO
2
 sensor 
8 Patient monitor  
9  Tube (preventing back flow) 
 
5  Adjust the power supply and turn on/off 3-way valves to ensure that that only one 
cylinder is connected to Mainstream CO
2
 sensor via 3-way valves at one time and the 
flowmeter reading is stable and within 2-5L/min. 
6  Switch between the two cylinders to connect Mainstream CO
2
 sensor at intervals of 6 
-10s and check if the displayed CO
2
 value is within 6±0.05%.