22
•
Maintenance
Probable causes
•
The calibration cylinder is low, out-dated, or defective.
•
If a demand flow regulator calibration kit is used, the demand flow regulator is not
functioning properly.
•
The sample-draw detector’s flow rate is too low because of an obstructed sample line,
failed pump, etc.
•
The sample-draw detector is malfunctioning.
Recommended action
1. Verify that the calibration cylinder contains an adequate supply of a fresh test sample.
2. If a demand flow regulator calibration kit is used, use a different demand flow regulator to
determine if the original one is functioning properly.
3. If necessary, set the correct flow rate with the sensor flow control valve.
4. If you cannot set the correct flow rate, check the sample line for obstructions or kinks.
5. If the calibration/response difficulties continue, replace the sensor as described later in this
section.
6. If the calibration/response difficulties continue, contact RKI Instruments, Inc. for further
instruction.
Replacing Components of the Sample-Draw Detector
This section includes procedures to replace the LEL sensor, LEL amplifier, carbon monoxide
sensor, carbon monoxide amplifier, hydrophobic filter, and particle filter.
Replacing the Combustible Gas Sensor
1. Turn off the controller.
2. Turn off power to the controller.
3. Open the housing door of the sample-draw detector.
4. Unscrew and remove the two screws that secure the sensor retaining plate, then lift the
plate, connector, and sensor out of the housing.
5. Unplug the connector from the sensor.
6. Verify that you are using the correct replacement sensor (NC-6245 is printed on the
sensor), then plug the sensor into the connector.
7. Place the sensor in the combustible gas sensor cavity, then position the retaining plate on
the two standoffs.
8. Secure the retaining plate to the standoffs with the two screws you removed in step 4.
9. Turn on power to the controller and place it into normal operation.
10. Turn on the controller.
