RKI Instruments 65-2435RK User manual

RKI Instruments, Inc.
www.rkiinstruments.com
65-2435RK
Hydrogen Compensated Carbon
Monoxide Transmitter
Operator’s Manual
Part Number: 71-0073RK
Revision: B
Released: 7/6/20

2 • 65-2435RK CO Transmitter
Product Warranty
RKI Instruments, Inc., warrants gas alarm equipment sold by us to be free from defects in
materials, workmanship, and performance for a period of one year from date of shipment from
RKI Instruments, Inc. Any parts found defective within that period will be repaired or
replaced, at our option, free of charge. This warranty does not apply to those items which by
their nature are subject to deterioration or consumption in normal service, and which must be
cleaned, repaired, or replaced on a routine basis. Examples of such items are:
Warranty is voided by abuse including mechanical damage, alteration, rough handling, or
repair procedures not in accordance with the operator’s manual. This warranty indicates the
full extent of our liability, and we are not responsible for removal or replacement costs, local
repair costs, transportation costs, or contingent expenses incurred without our prior approval.
THIS WARRANTY IS EXPRESSLY IN LIEU OF ANY AND ALL OTHER WARRANTIES
AND REPRESENTATIONS, EXPRESSED OR IMPLIED, AND ALL OTHER
OBLIGATIONS OR LIABILITIES ON THE PART OF RKI INSTRUMENTS, INC.,
INCLUDING BUT NOT LIMITED TO, THE WARRANTY OF MERCHANTABILITY OR
FITNESS FOR APARTICULAR PURPOSE. IN NO EVENT SHALL RKI INSTRUMENTS,
INC., BE LIABLE FOR INDIRECT, INCIDENTAL, OR CONSEQUENTIAL LOSS OR
DAMAGE OF ANY KIND CONNECTED WITH THE USE OF ITS PRODUCTS OR
FAILURE OF ITS PRODUCTS TO FUNCTION OR OPERATE PROPERLY.
This warranty covers instruments and parts sold to users by authorized distributors, dealers,
and representatives as appointed by RKI Instruments, Inc.
We do not assume indemnification for any accident or damage caused by the operation of this
gas monitor, and our warranty is limited to the replacement of parts or our complete goods.
a) Absorbent cartridges d) Batteries
b) Pump diaphragms and valves e) Filter elements
c) Fuses

65-2435RK CO Transmitter • 3
Table of Contents
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
CO Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Junction Box. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Mounting the CO Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Wiring the CO Transmitter to a Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Introducing Incoming Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Setting the Zero Signal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Operating With a Background of Hydrogen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Preventive Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Replacing Components of the CO Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Setting the Null Potentiometer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Calibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Preparing for Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Setting the Zero Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Setting the Response Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Returning to Normal Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

4 • 65-2435RK CO Transmitter
Overview
This manual describes the hydrogen compensated carbon monoxide (CO) transmitter. This
manual also describes how to install, start up, maintain, and calibrate the transmitter. A parts
list at the end of this manual lists replacement parts and accessories for the CO transmitter.
Specifications
Table 1 lists specifications for the CO transmitter.
Table 1: Specifications
Target Gas Carbon Monoxide (CO)
Area Classification Explosionproof for Class I, Groups B, C, and D
Input Voltage 19 - 30 VDC
Sampling Method Diffusion
Signal Output 4 to 20 mA
Detection Range 0 to 300 PPM (parts per million)
Response Time 90% in 30 seconds

65-2435RK CO Transmitter • 5
Description
This section describes the components of the CO transmitter. The transmitter consists of the
CO detector, amplifier, and junction box.
Figure 1: CO Transmitter Component Location
CO Detector
The CO detector includes the detector housing and sensor.
Detector Housing
The detector housing protects the sensing components within the housing. Use the mounting
threads at the top of the housing to screw the CO detector into the bottom conduit hub of the
junction box. Use the removable cap near the bottom of the housing to access the sensor for
maintenance or replacement. The cap protects the sensor from damage and includes a flame
arrestor which contains any sparks which may occur within the detector housing. Two cap
gaskets seal the interface between the housing and cap.
Two wires extend from the top of the detector housing. Use these wires to connect the CO
detector to the amplifier. The housing includes a four-socket pattern. This socket pattern
accepts the sensor’s four pins to secure the sensor within the detector housing. A pre-
amplifier, located between the sockets and two interconnect wires, conditions the sensor’s
Carbon Monoxide
Amplifier
Securing Screw(2)
Detector Housing Cap
Cap Gasket (x2)
TP-TP+
4-20mA
Transmitter
57-1252RK
FB
24V
NULL
SPAN RED
PWR
ZERO
SENSOR
BLK
GRN
BRN
WHT
3/4 NPT Conduit Hub
Flame Arrestor
Null
Potentiometer
Zero Potentiometer
Span Potentiometer
Detector Housing
Test Point (+)
Test Point (-)
Terminal Strip
Carbon Monoxide Detector

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 [H2S] 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.

65-2435RK CO Transmitter • 7
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 NPT 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 monitoring site. Use the cover on the front of the junction box to access the interior of the
junction box.
Installation
This section describes procedures to mount the CO transmitter in the monitoring environment
and wire the transmitter to a controller.
Mounting the CO Transmitter
1. Select a mounting site that is representative of the monitoring environment. Consider the
following when you select the mounting site.
• Select a site where the transmitter is not likely to be bumped or disturbed. Make sure
there is sufficient room to perform start-up, maintenance, and calibration procedures.
• Select a site where the target gas is likely to be found first.
NOTE: If your application does not require a specific mounting site, mount the transmitter at
approximately breathing level.

8 • 65-2435RK CO Transmitter
Figure 2: Mounting the CO Transmitter
If the CO detector is mounted to the junction box, skip to step 5. If not, continue with step 2.
2. Remove the junction box cover.
3. Guide the two wires that extend from the top of the CO detector through the bottom
conduit hub of the junction box.
4. Screw the CO detector into the bottom conduit hub of the junction box.
5. At the monitoring site, use #10 screws through the junction box’s two mounting holes to
secure the junction box to a vertical surface.
CAUTION: Mount the CO transmitter with the detector facing down (see Figure 2.)
Wiring the CO Transmitter to a Controller
WARNING: If the controller’s construction is not explosion-proof, the controller must be
installed in an ordinary location. Do non install a non-explosion-proof
controller in a classified location.
1. Turn off the controller.
2. Turn off or unplug incoming power at the power source end.
3. Remove the junction box cover.
Ø .25 Mouting Holes (2X)
3.4 max
3/4 NPT Conduit Hub
3.94
1.1
5.46
5.2
2.75
6.1
8.7 max

65-2435RK CO Transmitter • 9
4. Verify that the detector leads are wired to the amplifier’s terminal strip. If necessary,
connect the detector leads to the terminal strip as shown in Figure 3.
5. Guide a two-conductor, shielded cable or two wires in conduit through the top conduit hub
of the junction box.
WARNING: To maintain the explosion proof classification of the CO detector/junction box
combination, a conduit seal must be used within 2 inches of the junction box
conduit hub used for wiring to the controller. Adhere to your local electrical
code when installing the conduit seal.
6. Connect the two wires to the terminal strip as follows (see Figure 3.)
• Connect the positive wire to the terminal labeled 24V.
• Connect the feedback wire to the terminal labeled FB.
CAUTION: If using shielded cable, leave the drain wire insulated and disconnected at the
transmitter. You will connect the opposite end of the cable’s drain wire at the
controller.
7. Secure the junction box cover to the junction box.
8. Route the cable or wires leading from the CO transmitter through one of the conduit hubs
at the controller housing.
CAUTION: Do not route power and transmitter wiring through the same conduit hub. The
power cable may disrupt the transmission of the transmitter signal to the
controller.

10 • 65-2435RK CO Transmitter
9. Connect the wires to the to the applicable controller transmitter terminal strip as shown in
Figure 3.
Figure 3: Wiring the CO Transmitter to a Controller
10. Connect the cable’s drain to an available chassis ground at the controller.
FB
CO Detector/ H2 Compensated
Factory Wired
+24 VDC (19 - 30 VDC)
TP-
TP+
4-20mA
Transmitter
57-1252RK
4 - 20 mA In (FB)
Controller or
Recording Device
BLK
GRN
BRN
WHT
RED
CO Amplifier
WHT
BRN
GRN
BLK
SENSOR
ZERO
PWR
RED
SPAN
NULL
24V