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MR850 Technical Manual * Revision J * Issued November 2005 * Ref. 185041340 (185041713 internal)
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3. Connect the humidifier chamber inlet to the gas supply, and turn the humidifier on.
4. Wait approximately 30 minutes for the humidifier to stabilise.
Chamber and Airway temperatures can be checked by using the display mode (section 4.3.1)
and set temperatures can be checked by using the diagnostic menu (section 6.4).
After the humidifier has had time to warm up, the temperature at the airway and chamber should
be within +0.3 to -1.8°C of their set point, with no alarms occurring.
If any alarms do occur, refer to section 6 (troubleshooting), and determine the cause. If the
temperatures displayed are out of range, then refer to the MR850 operating manual, and check
the humidifier's setup.
8.2 Probe Accuracy Check
A probe accuracy check is used to test for the correct operation of the temperature / flow probe.
A Probe accuracy check consists of the following tests:
1. Probe Temperature Accuracy Test (section 8.2.1)
2. Probe Flow Accuracy Test (section 8.2.2)
8.2.1 Probe Temperature Accuracy Test
This test is used to determine the temperature accuracy of the temperature/flow probes that are
used with the MR850 humidifier.
Equipment Required:
• MR850 Humidifier
• Flow/Temperature Probe
• Accurate Thermometer (Accuracy ± 0.5 degrees )
• Container of water at approximately 40 °C, or a stirred water bath at 40 °C.
1. Perform a humidifier calibration test as outlined in section 8.1.2 to make sure the humidifier
is reading temperature correctly (ignore this step if recently completed).
2. Place both the airway and chamber probes in a container of water (at approx. 40 °C), along
with the accurate thermometer.
3. Make sure the water is constantly stirred, and wait approximately 30 seconds for the
temperature to stabilise.
4. Enter the service menu (refer section 8.1.1).
5. Select service mode number 4 (Temperature Probe Check) by pushing the mute button
when '-4-' 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 chamber temperature will be displayed; pressing the mode button will toggle between
the airway and chamber temperature.
8. Compare the temperatures obtained with the thermometer. The temperature difference
(between the humidifier temperatures and the thermometer) should not be greater than 1.5
degrees. If the difference is larger than 1.5 °C, the probe should be replaced.
8.2.2 Probe Flow Accuracy Test
This test is used to determine the flow accuracy of the temperature/flow probes that are used
with the MR850 humidifier.
Equipment Required:
• MR850 Humidifier
• Flow/Temperature Probe
• Suitable Breathing Circuit for MR850 (for example: 900RT100)
• Suitable Chamber for MR850 (for example: MR290)
• Gas supply - constant flow of: 10 ± 1 SLPM (Standard Litres Per Minute)