C
12-17 Combustible Gas Transmitter
15
O&M Manual
Rev-D
SENSOR RESPONSE TEST
While zero and span adjustments are required only periodically, gas sensors should be checked
regularly for proper response. The response check can be done quickly by simply aiming the outlet tube
from the span gas cylinder at the face of the sensor and turning on the gas flow for 10-20 seconds. The
sensor should begin to respond within 5 seconds.
To observe the response at the transmitter, it is necessary to connect a DVM to the test points
indicated in Figure 7. If the receiver is nearby, you may simply observe the digital display on the receiver.
If the sensor does not respond, it should be replaced.
SENSOR REPLACEMENT
Combustible gas sensors used in the C12 are warranted for 12 months and generally last 5 years
or more in the absence of poisoning agents. When sensor replacement is required, it can be done easily
and quickly. Open the transmitter and remove the sensor cable from the sensor terminal block on the
transmitter module. Unscrew the sensor from the explosion-proof transmitter housing using a wrench on
the hex provided on the sensor. Screw in the replacement sensor.
Connect the new sensor to the terminal block (figure 3), on the transmitter board and replace the
transmitter cover. After a new sensor has been connected, allow 4 hours for the new sensor to
completely stabilize. Then perform a zero and span calibration as described on pages 11 through 13.
