6 • 65-2435RK CO Transmitter
signal before the signal reaches the amplifier.
Sensor
The sensor is secured within the sensor housing by the four pins. Through a series of chemical
and electrical reactions, the sensor produces an electrical output that is proportional to the
detector range of the transmitter.
Charcoal Filter
The disc-shaped charcoal filter is secured to face of the CO sensor with a rubber boot. The
charcoal filter prevents interference gases (hydrogen sulfide [H
2
S] and certain hydrocarbons)
from producing false CO readings.
Amplifier
The amplifier converts the electrical output from the sensor to a 4 to 20 mA signal (that is
proportional to the detection range) and transmits the signal to a gas monitoring controller.
The amplifier includes the terminal strip, span potentiometer, zero potentiometer, and test
points (see Figure 1.)
Terminal Strip
The terminal strip is a seven-point terminal strip on the right side of the amplifier. Use the
terminal strip to connect the CO detector to the amplifier and the amplifier to a controller. The
terminal strip is a plug-in style which can be removed for wiring by pulling up on it.
NOTE:
The CO detector is factory-wired to the amplifier. See the Installation section of this
manual for all wiring procedures related to the transmitter.
Span Potentiometer
The span potentiometer is near the bottom of the amplifier. It is to the left of the zero
potentiometer. Use the span potentiometer to adjust the transmitter’s response output during
the calibration procedure.
Zero Potentiometer
The zero potentiometer is to the right of the span potentiometer. Use the zero potentiometer to
adjust the transmitter’s target gas-free output during the start-up and calibration procedures.
Null Potentiometer
The null potentiometer is on the left side of the amplifier. It is used to adjust the transmitters
hydrogen compensation when a CO sensor is replaced.
CAUTION:
The null potentiometer is factory set before shipment. It should only be adjusted
in the field when the CO sensor is replaced. This adjustment is made only once
after installing a new sensor. Do not adjust this pot when calibrating the CO
transmitter.
