RKI Instruments 65-2397-04 Series User manual

RKI Instruments, Inc.
www.rkiinstruments.com
65-2397-XX-04
CO2Transmitter
Operator’s Manual
Part Number: 71-0631
Revision: P1
Released: 4/7/23

2• 65-2397-XX-04 CO2Transmitter Operator’s Manual
WARNING
Read and understand this instruction manual before operating
transmitter. Improper use of the transmitter could result in bodily
harm or death.
Periodic calibration and maintenance of the transmitter is essential for
proper operation and correct readings. Please calibrate and maintain
this transmitter regularly! Frequency of calibration depends upon the
type of use you have and the sensor types. Typical calibration
frequencies for most applications are between 6 and 12 months, but
can be required more often or less often based on your usage.

65-2397-XX-04 CO2Transmitter Operator’s Manual • 3
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:
• Absorbent cartridges
•Fuses
• Pump diaphragms and valves
•Batteries
• Filter elements
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. INNO
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.

4• 65-2397-XX-04 CO2Transmitter Operator’s Manual
Table of Contents
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
CO2Detector. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Amplifier. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Amplifier Junction Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Detector Junction Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Mounting the CO2Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Wiring the Detector to the Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Wiring the Amplifier to a Controller. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Startup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Introducing Incoming Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Setting the Zero Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Preventive Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Replacing Components of the CO2Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Calibration Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Preparing for Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Setting the Zero Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Setting the Response Reading. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Returning to Normal Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

65-2397-XX-04 CO2Transmitter Operator’s Manual Overview • 5
Overview
This manual describes the 65-2397-XX-04 CO2transmitter. This manual also describes how to
install, start up, configure, maintain, and calibrate the transmitter when it is used with a gas
monitoring controller. A parts list at the end of this manual lists replacement parts and accessories
for the CO2transmitter.
Specifications
Table 1 lists specifications for the 65-2397-XX-04 CO2transmitter.
WARNING: When using the 65-2397-XX-04, you must follow the instructions and warnings
in this manual to assure proper and safe operation of the 65-2397-XX-04 and to
minimize the risk of personal injury. Be sure to maintain and periodically
calibrate the 65-2397-XX-04 as described in this manual.
Table 1: Specifications
Target Gas Carbon Dioxide (CO2)
Sampling Method Diffusion
Signal Output 4 to 20 mA
Detection Range
65-2397-01-04: 0-9,000 ppm
65-2397-02-04: 0-5,000 ppm
65-2397-03-04: 0-5% Volume
65-2397-04-04: 0-20% Volume
65-2397-05-04: 0-50% Volume
65-2397-10-04: 0-100% Volume
Response Time 90% in 45 seconds
Operating Temperature -4°F to 122°F (-20°C to 50°C)
Accuracy ± 5% of reading or ± 2% of full scale (whichever is greater)

6• Description 65-2397-XX-04 CO2Transmitter Operator’s Manual
Description
This section describes the components of the CO2transmitter. The transmitter is a 4 - 20 mA type
detector head. It consists of the hydrogen detector, calibration cup/splash guard, amplifier, the
amplifier junction box, and the detector junction box. The two-junction-box configuration is
intended for situations where the detector needs to be installed at an inaccessible location. The
detector junction box can be installed at the inaccessible location and the amplifier junction box
can be installed in a more readily accessible area.
Figure 1: CO2Transmitter Component Location
Black Detector J-Box
White
Green
B
Amplifier
Controller Terminal Strip
S
PWR / SIG
IR CO2 Detector
Calibration Cup/Splash Guard
WR
Amplifier J-Box
Detector Terminal
Strip
ZERO
SPAN
Red
G
LEL
Sensor
Current
mA

65-2397-XX-04 CO2Transmitter Operator’s Manual Description • 7
Infrared CO2Detector
The CO2detector consists of the detector housing body, detector housing cap, cap gasket, and the
plug-in sensor.
Figure 2: CO2Detector Component Location
Detector Housing Body
The detector housing body protects the electronic components within the housing. Use the
mounting threads at the top of the housing to screw the CO2detector into the 3/4 NPT hub on the
bottom of the junction box. Four color coded leads, red, white, green, and black, extend from the
other end of the detector. The leads allow you to connect the detector to the amplifier.
The housing includes three sockets installed on a circuit board. These sockets accept the plug-in
sensor’s three pins to provide an electrical connection for the sensor. The circuit board with the
sockets conditions the sensor’s signal before the signal reaches the amplifier.
Housing Cap & Cap Gasket
The housing cap screws onto the detector housing. It retains the plug-in sensor and protects it
from damage. A foam gasket is installed inside the housing cap that seals against the sensor face.
A hydrophobic membrane on the outside of the cap face keeps water and particulates away from
the sensor face behind the cap. Unscrew the detector cap to access the plug-in sensor for
maintenance or replacement. A cap gasket seals the interface between the housing and cap.
Plug-In CO2Sensor
The plug-in sensor is secured in the detector assembly by the housing cap. The sensor produces a
millivolt output that corresponds to the detection range of the transmitter.
Hydrophobic
Membrane
Cap Gasket
Plug-In CO2 Sensor
Sensor Retainer
Detector Housing Cap
Detector Housing Body

8• Description 65-2397-XX-04 CO2Transmitter Operator’s Manual
Amplifier
The amplifier converts the electrical output from the detector to a 4 to 20 mA signal that
corresponds to the detection range and transmits the signal to a gas monitoring controller. A foam
gasket that orients the amplifier and keeps it from rotating is installed on the bottom of the
amplifier. The amplifier includes the controller terminal strip, detector terminal strip, span pot,
zero pot, and test points (see Figure 3).
Figure 3: Amplifier Component Location
Controller Terminal Strip
The controller terminal strip is a three position plug-in style terminal strip located near the top of
the amplifier. Use the controller terminal strip to wire the CO2transmitter to a controller.
Detector Terminal Strip
The detector terminal strip is a four position plug-in style terminal strip located below the
controller terminal strip. Use the detector terminal strip to connect the CO2transmitter to the
amplifier.
NOTE: The IR CO2detector is factory-wired to the detector terminal strip. See “Wiring the
Amplifier to a Controller” on page 12 for all wiring procedures related to the
transmitter.
Zero Pot
The zero pot is located in the upper left corner of the amplifier (see Figure 3). Use a small flat
blade screwdriver to turn the zero pot’s adjustment screw and adjust the amplifier’s target gas-free
output during the start-up and calibration procedures. Turn the adjustment screw clockwise to
increase the zero output and counterclockwise to decrease the zero output.
Factory Adjust Pot
G
LEL BWR S
PWR / SIG
Detector Terminal
Strip
Span Pot
Amplifier
Controller Terminal Strip
ZERO
Sensor
Current
mA SPAN
Zero Pot
Factory Adjust Pot
Jumper Pins,
Factory Use Only
- Test Point
+ Test Point

65-2397-XX-04 CO2Transmitter Operator’s Manual Installation • 9
Span Pot
The span pot is located to the right of the zero pot (see Figure 3). Use a small flat blade
screwdriver to turn the span pot’s adjustment screw and adjust the amplifier’s gas response output
during the calibration procedure. Turn the adjustment screw clockwise to increase the gas
response and counterclockwise to decrease the gas response.
CAUTION: The amplifier includes two additional potentiometers. They are factory-set. Do not
adjust them.
Test Points
The test points are on the left side of the amplifier (see Figure 3). The test points produce a 100
mV to 500 mV output that corresponds to the transmitter’s 4 to 20 mA output. Use the test points
and a voltmeter to measure the amplifier’s output during the start-up and calibration procedures.
The black test point in the lower left corner is the negative (-) test point and the red test point
below the zero pot is the positive (+) test point.
Amplifier Junction Box
The amplifier junction box protects the amplifier and wiring connections made to the amplifier.
Use the top 3/4 NPT conduit hub to connect wiring from the amplifier to the controller. Use the
bottom 3/4 NPT conduit hub to wire the remotely installed CO2 detector. Use the cover on the
front of the junction box to access the interior of the junction box. The amplifier is factory
installed in the junction box. Three spacers installed on the back of the junction box controls the
distance of the junction box from a mounting surface.
Detector Junction Box
The detector junction box is intended to be installed remotely from the amplifier junction box.
The CO2detector is factory installed in the bottom 3/4 NPT conduit hub. A terminal strip is
provided for wiring connections and the detector is factory wired to one side of this terminal strip.
The other side of the terminal strip is for user-supplied wiring to the detector terminal strip located
in the amplifier junction box. This wiring should go through the top 3/4 NPT conduit hub. Three
spacers installed on the back of the junction box controls the distance of the junction box from a
mounting surface.
Installation
This section describes procedures to mount the CO2transmitter in the monitoring environment
and wire the transmitter to a controller.
Mounting the CO2Transmitter
1. Select a mounting site that is representative of the monitoring environment. Consider the
following when you select the mounting site:

10 • Installation 65-2397-XX-04 CO2Transmitter Operator’s Manual
• For the amplifier junction box, select a site where the junction box is not likely to be
bumped or disturbed. Make sure there is sufficient room to perform start-up, maintenance,
and calibration procedures. The site should be easily accessible.
• For the detector junction box, select a site where the target gas is likely to be found first.
For carbon dioxide, mount the remote detector at least six feet from the floor to minimize
the possibility of someone breathing on the unit. The exhaled CO2may cause an alarm.
• The junction boxes should be mounted no further than 200 feet from each other.
2. At the monitoring site you select, hang or mount the junction box with the detector facing
down (see Figure 2).
Figure 4: Mounting the CO2Transmitter
5.25 MAX
Rubber
Spacers,
3X
3.65
3/4 NPT
Female
IRCO2
Detector
J-Box
3.10
.75 .38
9.80 MAX
Calibration
Cup/Splash
Guard

65-2397-XX-04 CO2Transmitter Operator’s Manual Installation • 11
Wiring the Detector to the Amplifier
WARNING: Always verify that the power to the controller is off before you make wiring
connections.
1. Confirm that no power is being applied to the amplifier. If the amplifier has already been
connected to a controller, turn off the controller and turn off or unplug power to the controller.
2. Remove the detector junction box’s cover from the junction box.
3. Remove the amplifier junction box’s cover from the junction box.
4. Guide a four-conductor, shielded cable or four wires in conduit through the top conduit hub of
the detector junction box. To make wiring more convenient, use wire colors that correspond to
the detector wire colors: red, white, green, and black.
NOTE: Consult RKI Instruments, Inc. for cable lengths longer than 200 feet.
5. Connect the detector leads to the terminal block in the detector junction box.
6. Secure the detector junction box’s cover to the junction box.
7. Guide the other end of the four-conductor, shielded cable or four wires in conduit through the
bottom conduit hub of the amplifier junction box.
8. To gain access to a plug-in terminal strip for wiring, pull it out of its socket by grasping the
terminal strip and pulling. The detector strip is keyed so that the controller and detector
terminal strips cannot be reversed inadvertently.
9. Pull out the detector terminal strip and connect the four wires to the terminal strip as follows
(see Figure 5).
• Connect the wire corresponding to the detector’s red wire to the LEL “R” terminal.
• Connect the wire corresponding to the detector’s white wire to the LEL “W” terminal.
• Connect the wire corresponding to the detector’s green wire to the LEL “G” terminal.
• Connect the wire corresponding to the detector’s black wire to the LEL “B” terminal.
CAUTION: If shielded cable is used, leave the cable shield’s drain wire
disconnected and insulated at the detector junction box. You will
connect the opposite end of the cable’s drain wire to the amplifier
junction box’s chassis (earth) ground.

12 • Installation 65-2397-XX-04 CO2Transmitter Operator’s Manual
Figure 5: Wiring the Detector to the Amplifier
10. Reinstall the detector terminal strip into its socket.
11. If shielded cable is used, connect the cable’s drain wire to an available chassis (earth) ground
at the amplifier junction box. The amplifier mounting screw is a convenient grounding
location. Install a lug on the shield drain wire or wrap the shield drain wire around the
mounting screw. Do not connect the shield drain wire at the detector junction box.
Wiring the Amplifier to a Controller
WARNING: Always verify that the power to the controller is off before you make wiring
connections.
1. Turn off the controller.
2. Turn off or unplug power to the controller.
GR B
LEL S
PWR / SIG
W
Amplifier
Black Detector J-Box
IRCO2 Detector
Cable
Shield
Detector
Terminal
Strip
Black
Green
White
Red
Green
White
Red
Calibration Cup/Splash Guard
Amplifier
J-Box

65-2397-XX-04 CO2Transmitter Operator’s Manual Installation • 13
3. Remove the amplifier’s junction box cover.
4. Guide a three-conductor, shielded cable, or three wires in conduit through the top conduit hub
of the junction box.
5. Pull out the controller terminal strip, and connect the three wires to the terminal strip as
follows (see Figure 6).
• Connect the positive wire to the PWR/SIG “+” terminal.
• Connect the signal wire to the PWR/SIG “S” terminal.
• Connect the negative wire to the PWR/SIG “-” terminal.
CAUTION: If shielded cable is used, leave the cable shield’s drain wire
disconnected and insulated at the transmitter. You will connect the
opposite end of the cable’s drain wire to the controller’s chassis (earth)
ground.
6. Reinstall the controller terminal strip into its socket.
7. Secure the junction box cover to the junction box.
8. Route the cable or wires leading from amplifier junction box through one of the conduit hubs
at the controller housing. Use appropriate conduit fittings and construction technique for the
environmental rating of the controller. RKI controllers are typically rated NEMA 4X, are not
explosion-proof, and must be installed in a non-hazardous location.
CAUTION: Do not route power and transmitter wiring through the same controller
conduit hub. The power cable may disrupt the transmission of the
transmitter signal to the controller.

14 • Installation 65-2397-XX-04 CO2Transmitter Operator’s Manual
9. Connect the wires to the applicable detector/transmitter terminal strip at the controller as
shown in Figure 6.
Figure 6: Wiring the Amplifier to a Controller
10. If shielded cable is used, connect the cable’s drain wire to an available chassis (earth) ground
at the controller. RKI controllers typically have a ground stud that can be used to ground the
cable’s drain wire.
Controller
Amplifier (Transmitter)
Cable Shield
- (DC Ground)
+ 24 VDC
4 - 20 mA In (S)
B
Amplifier
J-Box
R W G PWR / SIG
LEL S

65-2397-XX-04 CO2Transmitter Operator’s Manual Start Up • 15
Start Up
This section describes procedures to start up the CO2transmitter and place the transmitter into
normal operation.
Introducing Incoming Power
1. Complete the installation procedures described earlier in this manual.
2. Verify that the power wiring to the controller is correct and secure. Refer to the controller
operator’s manual.
3. Turn on power to the controller.
4. Turn on the controller.
5. Verify that the controller is on and operating properly. Refer to the controller operator’s
manual.
NOTE: When first powered up, the transmitter will enter about a one minute period
when the 4-20 mA output is stabilizing and may be above the controller
alarm points or well below zero momentarily. RKI controllers have a one
minute warmup period when the controller does not display any gas reading
or give any alarm indication. The CO2transmitter’s 4-20 mA signal should
be stable by the time the controller’s warmup period is over.
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
Since there is a background of CO2in air of typically 300 - 600 ppm (0.03 - 0.06% volume), it is
necessary to use a calibration kit with a 100% nitrogen cylinder to set the zero signal of a CO2
transmitter with a low range detector. Fresh air can be used to zero the transmitter if a 0-20%
volume, 0-50% volume, or 0-100% volume detector is being used.
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.
The procedure below describes applying 100% nitrogen using a calibration kit that includes a
calibration cup, calibration gas, sample tubing, and a fixed flow regulator with an on/off knob.
RKI Instruments, Inc. recommends using a 0.5 LPM (liters per minute) fixed flow regulator.
1. Unscrew and remove the junction box cover from the junction box.
2. Set a voltmeter to measure in the millivolt (mV) range.

16 • Maintenance 65-2397-XX-04 CO2Transmitter Operator’s Manual
3. 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.
4. Screw the calibration cup onto the bottom of the IR CO2detector.
5. Screw the regulator into the 100% nitrogen calibration cylinder.
6. Use the calibration kit sample tubing to connect the regulator to the calibration cup.
7. Turn the regulator’s on/off knob counterclockwise to open it. Gas will begin to flow.
8. Allow the gas to flow for one minute.
9. Verify a voltmeter reading of 100 mV (±2 mV).
10. If necessary, use a small flat-blade screwdriver to adjust the zero pot until the voltmeter
reading is 100 mV (±2 mV).
11. Turn the regulator’s on/off knob clockwise to close it.
12. Unscrew the calibration cup from the detector.
13. Unscrew the regulator from the 100% nitrogen calibration cylinder. For convenience, leave
the sample tubing connected to the regulator and the calibration cup.
14. Store the components of the calibration kit in a safe and convenient place.
15. Remove the voltmeter leads from the test points.
16. Secure the junction box 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 CO2transmitter. It includes daily and biannual procedures.
Daily
Verify a display reading at the controller of the background concentration of CO2. Typical
background concentrations of CO2vary from about 300 to 600 ppm (0.03 to 0.06% volume)
depending on location. The 0-5,000 ppm, 0-9,000 ppm, and 0-5% volume detectors will display a
reading in a fresh air environment because they have low ranges. The 0-20% volume, 0-50%
volume, and 0-100% volume detectors will not display a reading in fresh air because their ranges
are too large. Investigate significant changes in the display reading.
Biannually
Calibrate the CO2transmitter as described in “Calibration” on page 22 of this manual.

65-2397-XX-04 CO2Transmitter Operator’s Manual Maintenance • 17
Troubleshooting
The troubleshooting guide describes symptoms, probable causes, and recommended action for
problems you may encounter with the CO2transmitter.
NOTE: This troubleshooting guide describes transmitter problems only. See the controller
operator’s manual for problems you may encounter with the controller.
Table 2: Troubleshooting the CO2Transmitter
Condition Symptom(s) Probable Causes Recommended Action
Fail
Condition
• Controller indicates
a fail condition.
• The transmitter
wiring is
disconnected or
misconnected.
• The wiring from the
detector to the
amplifier is
disconnected or
misconnected.
• The plug-in sensor is
not properly plugged
into the three-socket
pattern in the
detector housing
body.
• The transmitter’s
zero reading is low
enough to cause a
fail condition.
• The transmitter is
malfunctioning.
1. Verify that the transmitter wiring
to the controller is correct and
secure.
2. Verify that the wiring from the
detector to the amplifier is correct
and secure.
3. Confirm that the plug-in sensor is
properly installed.
4. Perform a zero adjustment. A full
calibration is recommended.
5. If the fail condition continues,
replace the sensor as described
later in this section.
6. If the fail condition continues,
contact RKI for further
instruction.

18 • Maintenance 65-2397-XX-04 CO2Transmitter Operator’s Manual
Replacing Components of the CO2Transmitter
This section includes a procedure to replace the hydrophobic membrane, a procedure to replace
the plug-in IR CO2sensor, a procedure to replace the entire CO2detector assembly, and one to
replace the amplifier. In most cases, it is not necessary to replace the entire detector assembly.
Replacing the Hydrophobic Membrane
1. Turn off the controller.
2. Turn off or unplug incoming power to the controller.
3. Unscrew the detector housing cap from the detector housing body.
4. Gently pry up the edge of the white hydrophobic membrane with a small flat blade
screwdriver or a similar tool.
5. Peel off the hydrophobic membrane. It may be necessary to clean off the detector housing cap
face to remove any residue left from the adhesive backed membrane.
6. Install the new membrane in the recess on the face of the detector housing cap.
7. Make sure the cap gasket is in place and screw the detector housing cap back onto the detector
housing body.
8. Turn on the power to the controller.
Slow or No
Response/
Difficult or
Unable to
Calibrate
•Unableto
accurately set the
zero or response
reading during
calibration.
•Transmitter
requires frequent
calibration.
NOTE: Under
“normal”
circumstances, the
transmitter requires
calibration once
every 6 months.
Some applications
may require a more
frequent calibration
schedule.
• The calibration
cylinder is low, out-
dated, or defective.
• The calibration gas is
not an appropriate
concentration.
• The membrane on
the detector housing
cap is blocked with
dirt or some other
particulate matter.
• The transmitter is
malfunctioning.
1. Verify that the calibration cylinder
contains an adequate supply of a
fresh test sample.
2. Check the face of the detector
housing cap and remove any
particulate contamination from
the hydrophobic membrane if
necessary.
3. Verify that the calibration gas
concentration is appropriate for
the transmitter.
4. If the calibration/response
difficulties continue, replace the
sensor as described later in this
section.
5. If the calibration/response
difficulties continue, contact RKI
for further instruction.
Table 2: Troubleshooting the CO2Transmitter (Continued)
Condition Symptom(s) Probable Causes Recommended Action

65-2397-XX-04 CO2Transmitter Operator’s Manual Maintenance • 19
9. Turn on the controller and place it into normal operation.
NOTE: When first powered up, the transmitter will enter about a one minute period
when the 4-20 mA output is stabilizing and may be above the controller
alarm points or well below zero momentarily. RKI controllers have a one
minute warmup period when the controller does not display any gas reading
or give any alarm indication. The combustible gas transmitter’s 4-20 mA
signal should be stable by the time the controller’s warmup period is over.
Replacing the Plug-In CO2 Sensor
1. Turn off the controller.
2. Turn off or unplug power to the controller.
3. Unscrew the detector housing cap from the detector housing body. Make sure not to lose the
cap gasket.
4. Unplug and remove the plug-in IR CO2 sensor.
5. Carefully plug the replacement sensor into the socket pattern that is located in the detector
housing.
6. Make sure the cap gasket is in place and screw the detector housing cap back onto the detector
housing body.
7. Turn on power to the controller.
8. Turn on the controller and place it into normal operation.
NOTE: When first powered up, the transmitter will enter about a one minute period
when the 4-20 mA output is stabilizing and may be above the controller
alarm points or well below zero momentarily. RKI controllers have a one
minute warmup period when the controller does not display any gas reading
or give any alarm indication. The CO2 transmitter’s 4-20 mA signal should
be stable by the time the controller’s warmup period is over.
CAUTION: Allow the replacement sensor to warm up for 5 minutes before you
continue with the next step.
9. Calibrate the transmitter as described in “Calibration” on page 22.
Replacing the IR CO2Detector
NOTE: In most cases it is only necessary to replace the IR CO2plug-in sensor.
1. Turn off the controller.
2. Turn off or unplug power to the controller.
3. Remove the junction box cover.

20 • Maintenance 65-2397-XX-04 CO2Transmitter Operator’s Manual
4. Remove the detector terminal strip from its socket.
5. Disconnect the detector leads from the detector terminal strip. Note the position of the color-
coded leads as you remove them.
6. Unscrew the detector from the junction box.
7. Guide the detector leads of the replacement detector through the bottom conduit hub of the
junction box, then screw the mounting threads of the detector into the conduit hub. If
necessary for environmental conditions, apply thread sealant or Teflon tape to the hub and/or
detector threads to seal them.
8. Connect the detector leads to the detector terminal strip as shown in Table 3 below and
Figure 6 on page 14 of this manual.
9. Reinstall the detector terminal strip into its socket.
10. Reinstall the junction box cover.
11. Turn on or plug in power to the controller.
12. Turn on the controller and place it into normal operation.
NOTE: When first powered up, the transmitter will enter about a one minute period
when the 4-20 mA output is stabilizing and may be above the controller
alarm points or well below zero momentarily. RKI controllers have a one
minute warmup period when the controller does not display any gas reading
or give any alarm indication. The CO2transmitter’s 4-20 mA signal should
be stable by the time the controller’s warmup period is over.
CAUTION: Allow the replacement detector to warm up for 5 minutes before you
continue with the next step.
13. Calibrate the transmitter as described in “Calibration” on page 22 of this manual.
Replacing the Amplifier
1. Turn off the controller.
2. Turn off or unplug power to the controller.
Table 3: Reconnecting the CO2Detector to the Amplifier
Detector Lead Detector Terminal
Strip
Red LEL “R”
White LEL “W”
Green LEL “G”
Black LEL “B”