MSA Orion G Operating Manual page 47

Chapter 4, Setting up the Gas Utility Instrument Operating Manual
Occasionally, it is necessary to remove the limits and allow the
instrument to calibrate over a much wider window. For example:
the installation of a new sensor may require that the limits be
expanded, since the output of the new sensor may be much
higher than the old sensor it is replacing. This most often occurs
with oxygen and combustible (LEL) sensors.
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