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Ref. 185040646 MR730/720/700/480 Technical Manual ¯ Revision F ¯ Issued March 2001
6.3.4 ALARMS CHECK - MR480
1Disconnect the 34.5°C temperature probe and check that the Temperature Probe LED flashes and gives an
audio alarm.
2 Insert the 41°C temperature probe into the humidifier and check that the Airway Temperature High LED flashes
and the audio alarm sounds.
3Push the Mute button and check that the audio alarm is silenced
4Go to the engineering menu and check that the heaterplate duty cycle (dc) is starting to decrease, this may take
a few seconds.
5Turn off the humidifier.
6Humidifier is now ready for use.
6.4 DUAL PROBE TEMPERATURE TEST
This test is recommended to be performed on all temperature probes every three months or if there is any doubt as to the
accuracy of the temperature probe. This test allows the operator to compare the temperature readings of both probes
(chamber and airway) firstly to one another, and secondly to a glass thermometer for absolute verification of temperature
if so desired. (Using a water bath and thermometer is the most reliable method to check the temperature probe accuracy.)
6.4.1 EQUIPMENT REQUIRED
♦Dual Temperature probe to be tested.
♦Glass thermometer accurate to ±1°C.
♦Cup of warm water (Ambient to 40 °C).
♦Heater wire if using humidifier in heater wire mode.
6.4.2 TEST PROCEDURE
1Plug the dual probe plug into the Humidifier, if in Heater Wire mode ensure a heater wire assembly is
connected.
2Turn on the mains power.
3Insert both temperature probes into a container filled with water at a temperature between ambient and 40 °C.
As temperature gradients can be quite large it is recommended that the two probes be held together with a
rubber band during this test and the water constantly stirred.
4Place the thermometer in the water alongside the probes and allow two minutes for the temperatures to
stabilise. It is recommended that the water be constantly stirred during this test.
5Enter the Engineering menu (refer Appendix A2) and select ‘CP’ (compare probes) option. The display will
alternate between the airway and chamber temperatures (chamber temperature is displayed with all decimal
points turned on).
6Check the temperature difference between chamber and airway probes as indicated by the display, it should not
exceed 1.5 °C.
7Ensure that the temperature reading of the chamber and airway probes are both within 1.5 °C of the
thermometer reading.