Emerson M21 Carbon Monoxide Alarm User Manual


 
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MAN-0076 Rev 05 Millennium II
December 07, 2012
Net Safety Monitoring Inc
4.2.2 (Cont’d) Zero calibration option
The “Zero” calibration option is selected if the sensor is only being zeroed (this not a complete calibration)
It does not require the application of span gas, as only the sensor’s zero point is adjusted. Ensure that no contaminants
are present, if the surrounding air is to be used for Zeroing. If Zero calibration is needed, at step 7 above, select ‘Zero
using switch 3).
Warning Air movement, drafts and wind can cause dilution of calibration gas flow which can cause an
erroneous calibration and inaccurate performance. To avoid this, use a Calibration Cup attached to the bottom of the
sensor. The cup doesn’t have to be removed for normal operation. When the cup is in place, inject calibration gas at a
rate of 0.5 1.0 liter per minute.