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MR850 Technical Manual * Revision J * Issued November 2005 * Ref. 185041340 (185041713 internal)
46
8.1.4 Humidifier Voltage Calibration Check
This check is required when the humidifier's PCBs have been serviced or replaced, or if the
mains transformer has been replaced.
Equipment Required:
• An AC voltmeter, capable of measuring RMS mains voltage to ±0.5 % accuracy.
• Suitable breathing circuit for MR850 (for example 900RT100).
• MR850 Heater Wire Adaptor (for example 900MR800).
1. Connect a breathing circuit to the humidifier with the heater wire adaptor. Make sure the
inspiratory limb is correctly plugged in, and that a temperature or calibration probe is not
plugged in to the humidifier.
2. Safely connect the AC voltmeter to the mains supply.
NOTE: Connect the voltmeter in close proximity to the mains socket used to power the
humidifier.
3. Enter the service menu (refer section 8.1.1).
4. Select service mode number 3 (Voltage Calibration Check) by pushing the mute button
when '-3-' is displayed.
5. Calculate the percentage of the actual mains voltage (the AC voltmeter reading) to the
nominal mains voltage for the humidifier model being tested.
NOTE: The nominal mains voltage is the voltage indicated on the left side of the humidifiers
case, and will be either 230 V~, 127 V~, 115 V~, or 100 V~.
Percentage mains = 100 x [Actual mains voltage (RMS) / Nominal Mains voltage]
For example:
MR850 Model AEK : Nominal Mains Voltage is 230 V~
Voltmeter Reading : 240.5 V~
Percentage mains: 100 x [240.5 / 230] = 104.5 %
Round any decimal points: 105
6. Adjust the reading on the humidifier's display to read the same as the value calculated
above. This is achieved by pushing the mode button to increase, or the power button to
decrease the percent value on the humidifier's display.
7. Check that the mains voltage has remained constant. If necessary recalculate the
percentage of actual mains voltage.
8. Store the new value in the humidifier's memory by pushing and holding the mute and mode
buttons together for 1 second. The humidifier will beep when the value has been correctly
stored.
9. Exit the voltage calibration test by pushing and holding down the mute button for longer than
one second.
8.1.5 Humidifier Warm-up and Control Check
This section describes how to check the humidifier's heater control systems. This test should
be performed if there is a problem with the humidifier, or after servicing of the humidifier.
Equipment Required:
• MR850 Humidifier
• MR850 Heater Wire Adaptor
• Flow/Temperature Probe
• Suitable breathing circuit for MR850 (for example: RT100)
• Suitable chamber for MR850 (for example: MR290) filled with water
• Gas supply - constant flow of: 10±5 SLPM (Standard Litres Per Minute)
1. Make sure that the humidifier passes the calibration and display checks (refer 8.1.2 and
8.1.3).
2. Set up the humidifier as shown in section 4.1. Make sure the chamber probe is correctly
inserted and invasive mode selected.