Manual

12 • Sample-Draw Hydrogen Sulfide Gas Detection
Recommended action
1. Verify that the calibration cylinder contains an adequate supply of a fresh test sample.
2. If necessary, set the correct flow rate with the bypass valve or flow adjust
potentiometer.
3. If you cannot set the correct flow rate, check the sample line for obstructions or kinks.
4. If the calibration/response difficulties continue, replace the sensor as described later
in this section.
5. If the calibration/response difficulties continue, contact RKI Instruments, Inc., for
further instruction.
Replacing Components of the Hydrogen Sulfide Gas
Sample-draw Detector
This section includes procedures to replace the sensor, filter, and ferrules.
Replacing the hydrogen sulfide gas sensor
1. Turn off incomming power.
2. Open the housing door of the sample-draw detector.
3. Unplug the sensor connector from the main circuit board.
4. Grasp the sensor firmly and pull it out of the flow chamber.
5. Install the new sensor in the flow chamber. Make sure it is pushed all the way down.
6. Connect the sensor connector to the main circuit board.
7. Turn on incomming power.
CAUTION: Allow the replacement sensor to warm up for 15 minutes before you continue.
8. Calibrate the replacement sensor as described in the “Calibration” section on page 14.
Replacing the filter
1. Open the housing door of the sample-draw detector.
2. Note the direction of the arrow on the filter. The arrow indicates the direction of the
sample flow.
3. Disconnect the filter from the elbows on each end of the filter, then remove the filter
from the sample-draw detector.
4. Make sure the arrow is pointing in the same direction as the arrow on the filter you
removed, then connect each end of the replacement filter to the elbows.
5. Verify that the flow rate is approximately 1.5 SCFH, then close the housing door.
Replacing the ferrules
The INLET and EXHAUST fittings each includes two ferrules that seal the incoming or
exhaust tubing to the fitting. Replace the ferrules if the seal is bad or if you replace the
sample tubing. Always replace the ferrules as a pair.
1. Disconnect the sample tubing from the fitting, then unscrew the nut from the fitting.
2. Verify that the ferrules did not remain in the nut. If necessary, remove the ferrules
from the nut.
3. Position the nut so the threaded end is facing you, then insert the back (smaller)