1.Perform a humidifier calibration check as outlined in section 8.1.2 (ignore this step if recently completed).

2.Set up the humidifier as shown in Figure 4.1. Make sure the chamber probe is correctly inserted into the breathing circuit.

3.Connect the humidifier chamber inlet to the gas supply.

4.Enter the service menu (refer section 8.1.1).

5.Select service mode number 5 (Flow Accuracy Check) by pushing the mute button when '-5- ' is displayed.

6.Plug the probe under test into the humidifier.

NOTE: If a probe fault condition exists, the humidifier will alarm at this time.

7.The humidifier will display '---' until a flow measurement has been acquired.

8.Check that the flow measurement is between 5 and 15 LPM.

9.If the flow measurement is outside this range, make sure there are no water drops or deposits on the temperature / flow probe's glass thermistor, and repeat test.

10.If the flow measurement remains outside the specified range, the probe should be replaced.

48 MR850 Technical Manual * Revision J * Issued November 2005 * Ref. 185041340 (185041713 internal)