RKI Instruments 65-2435RK - Manual (Page 6)

6 • 65-2435RK CO 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.
Test Points
The test points (labeled TP- and TP+) are near the top of the amplifier. The test points produce a
100 to 500 mV output that is proportional to the transmitter’s 4 to 20 mA output. Use the test points
and a voltmeter to measure the transmitter’s output during the start-up and calibration procedures.
Junction Box
Use the junction box to install the CO transmitter at a mounting site that is remote from the
controller. The junction box also protects the amplifier and wiring connections made to the
amplifier. Use the two 3/4 in. conduit hubs to mount the detector to the junction box (bottom hub)
and connect wiring from the amplifier to the controller (top hub).
NOTE: The CO detector and amplifier are factory-mounted to the junction box.
Use the junction box’s two mounting holes to mount the CO transmitter to a vertical surface at the