RKI Instruments M2A - Manual (Page 52)

47 M2A Transmitter Operator’s Manual
5. Turn the regulator knob clockwise to close the regulator.
6. Unscrew the nitrogen cylinder from the fixed flow regulator and unscrew the calibration cup
from the detector. The M2A will continue to display the minimum gas response on the display
and retain the response level in its memory.
7. Adjust the oxygen reading up or down to match the 100% nitrogen cylinder oxygen
concentration of 0 by using the UP/YES and DOWN/NO buttons.
NOTE: If a cylinder other than a 100% nitrogen (0% oxygen) cylinder is used to set the zero
reading, such as a cylinder with 12% oxygen, set the zero reading to match the
cylinder’s oxygen concentration.
8. Press and release the ENTER button. The M2A will perform a zero operation. The display will
indicate ZERO Gas PASS for a few seconds, then indicate ZERO Gas SAVED before
indicating Leaving CAL Mode for a few seconds.
NOTE: If the zero adjustment fails, see “Troubleshooting” on page 39 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 17.4 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 M2A
Replacing the Gas Detector
NOTE: For M2A versions that do not have a replaceable plug-in sensor, or if you determine
that it is necessary to replace the entire detector, use the procedure in this section to
change the entire detector. For M2A versions that include a replaceable plug-in sensor,
see the appropriate instructions in the sections that follow this one to replace the plug-in
sensor.
1. Turn off or disconnect power to the M2A.
2. Remove the junction box cover.
3. Grasp the control PCB by its edges.
4. Gently pull until the control PCB is pulled away from the banana jacks. Take care not to pull
too hard and damage the cable which connects the control and terminal PCBs.
5. Let the control PCB hang by the cable. The terminal strips are now visible on the terminal
PCB. The control PCB may be left hanging while wiring is done. If desired, the control PCB
may be disconnected from the cable and set aside while wiring.
6. Remove the detector terminal strip from its socket.
7. Disconnect the detector leads from the detector terminal strip. Note the position of the color-