Adjustments
Care and Maintenance • 27
5.2. Adjustments
5.2.1. Introduction
Adjustment of the detector must be performed at regular intervals as required by
national standards or regulations
(For example, EN 378, ASHRAE 15, BREEAM,
etc.).
Breathing Hazard:
Calibration gas
MUST NOT
be inhaled! See appropriate Safety
Data Sheets. Calibration gas should be vented into a fume hood or to the outside of
the building.
Zero First, Then Span:
For proper operation, never adjust the span before
completing a zero adjustment. Performing these operations out of order will cause
faulty calibration.
IMPORTANT: Emerson recommends calibrating detectors within the application-specific
condition and with target gas. This method of zeroing the detector in the application
environment and performing a target gas calibration is more accurate. A surrogate gas
calibration may only be performed as an alternative if a target gas calibration is
not possible.
IMPORTANT: The sensor should be fully stabilized (at least 2 hours, preferably 24 hours).
IMPORTANT: When entering the functions for zero or span adjustment, the detector will
automatically enter OFFLINE mode, and will remain OFFLINE until either the
OFFLINE mode is canceled by tapping the respective magnetic switch, or the OFFLINE
mode times out within 6 minutes (typical) after the adjustment has ended.
5.2.2. General Calibration Procedure
IMPORTANT: The MRLDS-450 Gas Detector MAY NOT be in an alarm or fault condition
during calibration. Acknowledge any alarms or faults BEFORE attempting to begin the
calibration process.
IMPORTANT: Except for CO
2
or O
2
sensors, calibration gas must be in a balance of air,
not nitrogen (N
2
).
