As revisions to the software become available, the MR400 can be updated; refer to the service
manual (REF 989803181911). It is recommended that you backup your settings prior to updating
software, so that they can be restored afterward; see Edit User Settings on page 3‐15.
Expression MR400 Instructions for Use
Insert a new O2 sensor into the sensor port and then, using the
sensor tool, turn the sensor clockwise until secure.
Replace the service panel cover and secure it using the two screws.
Connect a gas sampling line to the water trap.
Turn on the MR400.
Turn on the Agents parameter and allow the system to run until
CO2 Warming Up is no longer displayed.
Calibrate the O2 sensor by performing the following steps:
a. Press the Monitor key.
b. On the Monitor Setup menu, select Service(Bio‐Med).
c. On the Service(Bio‐Med) menu, select Gas Cal.
d. On the Gas Cal menu, select O2 Cal.
e. When prompted: Flow Room Air for 10 Seconds, Do you
wish to continue? Select Yes to proceed.
Readjusting CO2 Zero will be displayed until calibration is
Maintenance and Troubleshooting 14‐15