4.1.2Non-Heater Wire Operation (Software version 7.23 only)

Ventilator/Gas Supply

RT134 Breathing Circuit

Temperature Probe

Chamber

Probe

MR290 Chamber

Airway Probe

Water trap

MR850 Humidifier

Figure 4.2 Typical Non-Heater Wire Humidifier Setup

In this application the MR850 maintains the airway temperature at the desired set point (invasive 37 °C or non-invasive 31 °C) by heating the chamber of water through the heater plate. As the gas cools considerably down the unheated circuit, a water trap circuit must be used to collect the resulting condensate.

Activating Non-Heater Wire Operation

Refer also to the diagnostic menu in section 6.4.

1Turn on the humidifier with NO heated circuit connected, and mute the heater wire alarm.

2Access the diagnostic menu by pressing the mute and mode buttons together for 1 second, the display should show two rows of dashes ‘= = =’. Releasing both buttons will allow the diagnostic menu to cycle automatically.

3Allow the menu to cycle through to “cct” – the circuit identification. Press mute to access this function.

4To enable non-heated operation, press both mute and mode buttons simultaneously for 1 second, the humidifier will beep twice and the temperature display will show “nhh”. Release both buttons. The humidifier is now configured for non-heated circuits. This setting will be remembered each time the humidifier is turned on.

Deactivating Non-Heater Wire Operation

The simplest way to de-activate non heater wire operation is to connect a heated breathing circuit. Alternatively it can be de-activated the same way that non-heated circuit operation was activated (see above).

4.1.3Stand-by Operation

If the humidifier detects a problem with its setup or operation it will alarm. Depending on the severity of the alarm condition, the humidifier will either remove all power from the heating systems, or enter stand-by. The humidifier will also enter stand-by if the gas flow through the breathing circuit has stopped.

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

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