65-2646RKS-SW M2A Transmitter Operator’s Manual
Chapter 7: Maintenance
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39
4. Allow calibration gas to flow for two minutes. The gas reading should be stable after two
minutes.
5. Turn the regulator knob clockwise to close it.
6. Unscrew the calibration gas cylinder from the fixed flow regulator and unscrew the
calibration cup from the detector. The M2A will continue to display the maximum gas
response on the display and retain the response level in its memory.
7. Adjust the gas reading up or down to match the calibration gas cylinder concentration by
using the UP/YES and DOWN/NO buttons, then press and release the ENTER button.
NOTE:
The detector must be calibrated with a gas concentration between 10% and
100% of the channel’s full scale value (i.e. between 30 ppm and 300 ppm
CO).
8. The M2A will perform a span operation. The display will indicate
SPAN Gas PASS
for a few
seconds, then indicate
SPAN Gas SAVED
before indicating
Leaving CAL Mode
for a few
seconds.
NOTE:
If the span adjustment fails, see “Troubleshooting” on page 34 for
recommended actions.
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 will return to normal operation.
10. Store the components of the calibration kit in a safe place.
Replacing Components of the CO Detector
This section includes a procedure to replace the charcoal filter, the CO plug-in sensor and the
entire detector assembly. In most cases, it is not necessary to replace the entire detector assembly.
Replacing the CO Sensor Charcoal Filter
The charcoal filter is used to scrub out interfering gases from the environment being monitored,
such as H
2
S and certain hydrocarbons. If you are experiencing unexplained upscale readings on a
CO M2A, the charcoal filter may be saturated and no longer scrubbing out interfering gases and it
may be necessary to change the charcoal filter.
1. Turn off or disconnect power to the M2A.
2. Unscrew the detector housing cap from the housing body. Make sure not to lose the cap
gasket. See Figure 2 for an illustration of the CO detector.
