M2A-XL Transmitter Operator’s Manual
Chapter 7: Maintenance
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9. The display will now alternate between the normal operation screen and the message
REMOVE CAL GAS
for 1 minute. If the calibration gas has not been removed from the
detector, remove it now to avoid unwanted alarms.
During this 1 minute period, the signal output will remain fixed at 3.5 mA and the relays
will remain in their non-alarm state to avoid unwanted alarms while the calibration gas
clears from the detector. At the end of the 1 minute period, the
REMOVE CAL GAS
message will stop appearing and the M2A-XL will return to normal operation.
10. Store the components of the calibration kit in a safe place.
Calibration, Oxygen Version
This section describes how to calibrate the oxygen version of the M2A-XL. It includes procedures
to prepare for calibration, enter Calibration Mode, set the fresh air (span) reading, set the zero
reading, and return to normal operation.
NOTE:
An O
2
detector must be calibrated with 0 - 18% O
2
.
WARNING: The M2A-XL is not an active gas monitoring device during the calibration
procedure. The 4-20 mA output signal will “freeze” at 17.4 mA and all relays will
remain in their non-alarm state while the M2A-XL is in Calibration Mode. The
output signal will not indicate current readings and the relays will not resume
operating normally until the M2A-XL is in normal operation again.
Preparing for Calibration
NOTE:
The following procedure assumes the use of a calibration kit which includes a zero air
(20.9% oxygen) calibration cylinder to set the fresh air reading, a 100% nitrogen (0%
oxygen) calibration gas cylinder to set the zero reading, a fixed flow regulator with an
on/off knob, a calibration cup, and a short piece of sample tubing to connect the
regulator to the calibration cup. A cylinder with up to an 18% oxygen concentration
may be used instead of a 100% nitrogen cylinder to set the zero reading.
NOTE:
While in calibration mode, if there is no switch activity for the calibration time-out
period the unit will return to normal operation. See “Viewing & Changing M2A-XL
Parameters” on page 47 for instructions to set the calibration time-out.
NOTE:
The following procedure assumes that the oxygen concentration in the calibration area
is not normal, 20.9%, but is oxygen deficient. If a fresh air environment can be verified,
applying zero air to the detector is not necessary when adjusting the fresh air (span)
setting.
1. Connect the calibration kit sample tubing to the calibration cup hose barb.
