14 • 65-2405RK-05-04 Combustible Gas Transmitter
CAUTION:
Allow the detector to warm up for 5 minutes before you continue with the next section,
“Setting the Zero Signal”.
Setting the Zero Signal
WARNING: Do not remove the junction box cover while the circuits are energized unless the area
is determined to be non-hazardous. Keep the junction box cover tightly closed during
operation.
CAUTION:
If you suspect the presence of combustible gas in the monitoring environment, use the
calibration kit and the zero air calibration cylinder to introduce “fresh air” to the
detector and verify an accurate zero setting. See “Calibration” on page 19 for
instructions to apply zero air when setting the zero signal.
1. Verify that the transmitter is in a fresh air environment (environment known to be free of
combustible gas).
2. Unscrew and remove the amplifier junction box’s cover from the junction box.
3. Set a voltmeter to measure in the millivolt (mV) range.
4. Plug the voltmeter leads into the test points on the amplifier. Plug the positive lead into the red (+)
test point; plug the negative lead into the black (
-
) test point.
5. Verify a voltmeter reading of 100 mV (±2 mV).
6. If necessary, use a small flat-blade screwdriver to adjust the zero pot until the voltmeter reading is
100 mV (±2 mV).
7. Remove the voltmeter leads from the test points.
8. Secure the amplifier junction box’s cover to the junction box.
Maintenance
This section describes maintenance procedures. It includes preventive maintenance, troubleshooting,
and component replacement procedures.
Preventive Maintenance
This section describes a preventive maintenance schedule to ensure the optimum performance of the
combustible gas transmitter. It includes daily and quarterly procedures.
Daily
Verify a display reading of 0% LEL at the controller. Investigate significant changes in the display
reading.
Quarterly
Calibrate the combustible gas transmitter as described in “Calibration” on page 19 of this manual. See
the calibration frequency discussion in “Calibration Frequency” on page 18 to determine if a quarterly
calibration schedule fits your needs.
