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Ref. 185040646 MR730/720/700/480 Technical Manual ¯ Revision F ¯ Issued March 2001
3.0 ALARMS AND INDICATORS _____________________________________
3.1 TEMPERATURE PROBE ALARM
If the airway temperature probe is disconnected or develops a low or high resistance the Temperature Probe alarm will be
enabled. Indication is by a ‘- - -' message on the airway temperature display plus a flashing Temperature Probe red LED
and an audio alarm.
Five specific fault types can be diagnosed and are displayed by the sequence of ‘decimal points’ in the display, as
shown below:
a
- - -
Temperature Probe not plugged in.Low temperature (~ 0 °C)
Open circuit chamber outlet probe
Open circuit in common lead in probe cable.
b
- - -.
Open circuit patient airway probe
Very low temperature (~ 0 °C)
c
- -.-
Short circuit chamber outlet probe
Very high temperature (~ 100 °C)
d
- -.-.
Short circuit patient airway probe
Very high temperature (~ 100 °C)
e
-.- -
Short in probe cable between patient airway probe and chamber outlet probe
The faults (a to d) above are checked for at a rate of about twice per second. The final fault (e) which does not
immediately cause any apparent operating anomaly is checked twice a minute.
A Temperature Probe Alarm immediately shuts down both heater wire and heaterplate.
Once the alarm condition has been removed the humidifier will enter warm up mode (refer § 2.6).
3.2 ALARMS IN HEATER WIRE MODE (MR700/720/730 ONLY)
3.2.1 HEATER WIRE ALARM
If the heater wire is disconnected or there is a fault with the heater wire circuit, then the Heater Wire alarm LED will start
flashing and the audio alarm will be enabled. Both heater wire and heaterplate circuits will be shutdown. The display will
continue to indicate the temperature sensor reading (unless the heater wire fuse is open circuit).
An open circuit heater wire fuse is indicated by ‘F-2’ appearing on the Airway Temperature display.
On MR720/730 if the Heater Wire is connected but switched off, the alarm will sound (refer § 2.2.4).
Note: If ‘F-2’ is displayed and the F2 fuse is intact then check the calibration of the 41 °C overheat (refer § 5).
3.2.2 AIRWAY TEMPERATURE HIGH ALARM
The red Airway Temp High LED will flash and an audible alarm will sound if the gas temperature being delivered to the
patient is 2 °C higher than the Temperature Control setting. A high temperature alarm instantly disables both heater
circuits.
3.2.3 AIRWAY TEMPERATURE LOW ALARM
The red Airway Temp Low LED will flash and an audible alarm will sound if the gas temperature being delivered to the
patient is 2 °C lower (4 °C for MR720 model) than the Temperature Control setting. If Airway Temperature Low alarm
condition persists for more than 100 seconds the heaterplate and heater wire circuits will switch off. Pressing the mute
button will silence the Audio alarm and resume heat for a further 100 seconds, the Airway Temperature Low LED will
continue to flash. This alarm is disabled during warm-up. See § 2.6.1.
If the airway temperature drops below 5°C the display will show ‘LO’ and an audible alarm will sound.