RKI Instruments 65-2394RK User Manual

65-2394RK

Combustible Gas Transmitter

Part Number: 71-0181RK
Revision: A
Released: 4/12/11

Operator’s Manual

RKI Instruments, Inc.

www.rkiinstruments.com

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 tra nsmitt er regula rly! 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.

65-2394RK Combustible Gas 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 fr o m date of shipment
from RKI Instruments, Inc. Any parts found defective withi n tha t 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 ser v ice, and
which must be cleaned, repaired, or replaced on a routine basis. Examples of such items
are:

W arranty 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 , a nd we are not r esponsible for removal or r eplacement costs,
local repair costs, transportation costs, or contingent expenses incurred without our prior
approval.

a) Absorbent cartridges d) Batteries
b) Pump diaphragms and valves e) Filter elements
c) Fuses

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 A
PARTICULAR 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 assum e i ndemnification for any accident or damage caused by the op e r a t ion of
this gas monitor, and our warranty is limited to the replacement of parts or our complete
goods.

65-2394RK Combustible Ga s Tr ans mitte r

Table of Contents

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Combustible Gas Detector. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Junction Box. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Mounting the Combustible Gas Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Wiring the Combustible Gas Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Startup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Introducing Incoming Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Setting the Zero Signal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Preventive Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Replacing Components of the Combustible Gas Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Calibration Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Preparing for Calibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Setting the Zero Reading. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Setting the Response Reading. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Returning to Normal Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

65-2394RK Combustible Gas Transmitter

Overview

This manual describes the 65-2394RK combustible gas transmitter. This manual also
describes how to install, start up, con fi gure, mainta in, a nd ca librate 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 combustible gas transmitter.

Specifications

Table 1 lists specifications for th e combustible gas transmitter.

Target Gas 65-2394RK-CH4: Methane (CH4)

Area Classification Explosionproof for Class I, Groups B, C, and D

Sampling Method Diffusion

Table 1:Specifications

Description Specification

65-2394RK-HC: Propane

Signal Output 4 to 20 mA
Detection Range 0 to 100% LEL
Response Time 90% in 45 seconds
Operating Temperature
Accuracy ± 5% of reading or ± 2% of full scale (whichever is gr eater)

-4°F to 122°F (-20°C to 50°C)

W ARNING: When using the 65-2394RK, you must follow the instructions and warnings

in this manual to assure proper and safe operation of the 65-2394RK and to
minimize the risk of personal injury. Be sure to maintain and period ically
calibrate the 65-2394RK as described in this manual.

65-2394RK Combustible Gas Transm itter • 1

Description

al

The 65-2394RK combustible gas transmitter has two versions, the 65-2394RK-CH4 which
is calibrated to methane and the 65-2394RK-HC which is calibrated to propane. The
transmitter utilizes an infrared type of detector which has some a dvantages over a
catalytic type of combustible detector. The infrared detector will generally have a longer
service life than a catalytic detector, it will require calibration less often, and it can detect
combustible gas even if there is no oxygen in the sample which allows detection of
combustible gas in an inert atmosphere.

This section describes the components of the combustible gas transmitter. The transmitter
is a 4 - 20 mA type detector head. It consists of the combustible gas detector, amplifier , and
junction box.

Factor y Adjust Pot

Span Pot

Zero Pot

Factory Adjust

Pot

umper Pins,
Factory Use

Only

+ Te st Poi n t

- Test Poin t

Controller Terminal
Strip

Amplifier

SPAN

ZERO

Sensor

Current

mA

S

PWR / SIG

S2 001

57-1053RK

GWRB

LEL

Detector Termin
Strip

J-Box

Figure 1: Combustible Gas Transmitter Component Location

Infrared LEL Detector

The infrared LEL detector is made up of a miniature infrared combustible gas LEL
detector housed and encapsulated in a pipe nipple. The pipe nipple has 3/4” NPT thr eads
on each end and a 1 1/4” hex that allows removal or installation of the detector with a

2 • 65-2394RK Combustible Gas Transmitter

IR L EL D e tecto r

wrench. A por ous flame arr e stor t hat is coat ed wit h a hydr o phobic f ilm that re pels liquids
is on one end of the detector and al lows samp le gas to enter the detector. 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. To distinguish the propane detector
from the methane detector (in case the replacement sensor label that is applied to one of
the leads is lost), a short length of red shrink tubing is a pplied to the white wire of the
propane detector near where the wire comes out of the nipple.

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. A label on the amplifier indicates the detector drive current. This
drive current is factory set and is dictated by the combustible gas to which the detector is
calibrated. Consult RKI Instruments, Inc. if you plan to change the calibration gas for the
transmitter, for e xample from a methane calibration to a hexane calibration. The amplifier
includes the detector terminal strip, controller terminal strip, span pot, zero pot, and test
points (see Figure 1).

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 combustible gas
transmitter 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 IR LEL detector to
the amplifier.

NOTE: The IR LEL detector is factory-wired to the detector terminal strip. See “Wiring

the Combustible Gas Transmitter to a Controller” on page 5 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 1). Use a small
flat blade screwdriver to turn the zero pot’s adjustment screw and adjust th e amplifier’s
zero (fresh air) 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.

Span Pot

The span pot is located to the right of the zero pot (see Figure 1). 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.

65-2394RK Combustible Gas Transm itter • 3

Installation

Test Points

The test points are on the left side of the amplifier (see Figure 1). 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 star t-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.

Junction Box

Use the junction box to install the transmitter at a mounting site that is remote from the
controller. The junction box protects the amplifier and wiring connections made to the
amplifier. Use the to p 3/ 4’’ conduit hub to connect wiring from the amplifier to the
controller. Use the cover on the front of the junction box to access the in terior of the
junction box. The detector and amplifier are factory installed in the junction box. Three
spacers installed on the back of the junction box control the distance of the junction box
from a mounting surface and ensure that there is enough room to install a calibration cup
on the detector during calibration.

This section describes procedures to mount the combustibl e gas transmitter in the
monitoring environment and wire the transmitter to a controller.

Mounting the Combustible Gas 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. For lighter gases,

mount the detector near the ceiling; for heavier gases, mount the detector near the
floor.

4 • 65-2394RK Combustible Gas Transmitter

3/4 NPT

Female

.382.70

3.65

7.10 MAX
Rubber

Spacer,
3X

J-Box

IR LEL Detector

.75

Figure 2: Mounting the Combustible Gas Transmitter

2. At the monitoring site you select, hang or mount th e jun c tion box with the detector
facing down (see Figure 2).

Wiring the Combustible Gas Transmitter 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 pow er to the co ntroller.

3. Remove the junction box cover.

4. The detector leads are factory wired. Verify that the detector leads are wired to the
amplifier’s detector terminal strip as shown in Figure 3.

5. To gain access to a plug-i n terminal strip for wiring, pull it out of its socket by
grasping the terminal strip and pulling. The detecto r strip is keyed so that the
controller and detector terminal strips cannot be reversed inadvertently.

65-2394RK Combustible Gas Transm itter • 5

6. Guide a three-conductor, shielded cable, or three wires in conduit through the top
conduit hub of the junction box.

7. Pull out the controller terminal strip, and connect the three wires to the terminal strip
as follows (see Figure 3).

• 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.

8. Reinstall the controller terminal strip into its socket.

9. Secure the junction box cover to the junction box.

10. Route the cable or wires leading from the combustible gas transmitter through one of
the conduit hubs at the controller housing.

CAUTION: Do not route power and transmitter wiring through the same controller conduit hub.

The power cabl e may disrupt the transmission o f the transmitte r signal to the
controller.

11. Connect the wires to the applicable detector/transmitter terminal strip at the
controller as shown in Figure 3.

6 • 65-2394RK Combustible Gas Transmitter

Cable Shield

J

+ 24 VDC
4 - 20 mA In (S)

- (DC Ground)

-Box

Contr oller or

Recording Device

Amplifier (Transmitter)

S

PW R / SI G

B

GW

LEL

R

Black
Green

White
Red

Detector Wires

IR LEL Dete ct or

Figure 3: Wiring the Combustible Gas Transmitter to a Controller

12. 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.

65-2394RK Combustible Gas Transm itter • 7

Start Up

This section describes procedures to start up the combustible gas transmitter and place th e
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 ma nual.

NOTE: When first powered up, the transmitter will enter about a one minute period

when the 4-20 mA output is stab ilizing 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.

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

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.

NOTE: If you can verify that the combustible gas transmitter is in a fresh air

environment, you do not need to apply zero air to the detector before adjusting
the zero reading.

The procedure below describes applying zero emission air, usually called zero air , 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.

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 LEL detector.

5. Screw the regulator into the zero air calibration cylinder.

6. Use the calibration kit sample tubing to connect the regulator to the calibration cup.

8 • 65-2394RK Combustible Gas Transmitter

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 re ading of 100 mV (±2 mV).

10. If necessary, use a small flat-blade screwdriver to adjust the zero pot until the

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 zero air calibration cylinder. For convenience, leave

14. Store the components of the calibration kit in a safe and conve nient 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.

voltmeter reading is 100 mV (±2 mV).

the sample tubing connected to the regulator and the calibration cup.

Preventive Maintenance

This section describes a preventive maintenance schedule to ensure the optimum
performance of the combustible gas transmitter. It includes daily, monthly, and biannua l
procedures.

Daily

Verify a display reading of 0 %LEL at the controller. Investigate significant changes in the
display reading.

Monthly

This procedure describes a test to verify that the combustible gas transmitter responds
properly to the target gas.

WARNING : The controller is not an active gas monitoring device during the response

test procedure.

NOTE: Performing a response test on the combustible gas transmitter may cause alarms.

Be sure to put the controller into its calibration mode or disable external alarms
before performing this test.

NOTE: The following procedure assumes the use of a calibration kit which includes a

calibration gas cylinder, a 0.5 LPM fixed flow regulator with an on/off knob, a
calibration cup for the detector, and a length of sample tubing.

Preparing for the response test

1. Place the controller into its calibration mode or disable external alarms.

2. Verify that the controller display reading for the cha nnel you are testing is 0 %LEL.

65-2394RK Combustible Gas Transm itter • 9

If the display reading is not 0 %LEL, set the zero reading of the transmitter as
described in “Start Up” on page 8, then continue this procedure.

3. Screw the regulator into the calibration cylinder.

4. Screw the calibration cup onto the bottom of the detector.

5. Use the calibration kit sample tubing to connect the regulator to the calibration cup.

6. Set a voltmeter to measure in the millivolt (mV) range.

7. 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.

8. Use the following formula to determine the correct test points output for the test
sample.

Output (mV) = (calibrating sample/fullscale) X 400 + 100

For example, with a test sample of 50 %LEL and a fullscale setting of 100 %LEL, the
correct output is 300 mV.

300 (mV) = (50/100) X 400 +100

Performing the response test

1. Turn the regulator’s on /off knob counterclockwise to open the regulator. Gas will
begin to flow.

2. Allow the gas to flow for one minute.

3. Verify that the reading is within ± 20% of the response reading you determined earlier.

NOTE: If the reading is not within ± 20% of the correct response reading, calibrate the

transmitter as described in “Calibration” on page 14 of this manual.

4. Turn the regulator’s on/off knob clockwise to close the regulator.

5. Unscrew the regulator from the calibration cylind er.

6. Unscrew the calibration cup from the detector.

NOTE: For convenience, leave the regulator and calibration cup connected by the

sample tubing.

7. Remove the voltmeter leads from the amplifier test poin ts.

8. Reinstall the junction box cover.

9. When the controller display reading falls below th e alarm setpoints, return the
controller to normal operation.

10. Store the components of the calibration kit in a sa fe place.

Biannually

Calibrate the combustible gas transmitter as described in “Calibration” on page 14 of this
manual.

10 • 65-2394RK Combustible Gas Transmitter

Troubleshooting

The troubleshooting guide describes symptoms, probable causes, and recommended
action for problems you may encounter with the combustible gas transmitter.

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 Combustible Gas Transmitter

Condition Symptom(s) Probable Causes Recommended Action

Fail Condition • Controller indicates a

Slow or No
Response/
Difficult or
Unable to
Calibrate

fail condition.

• Transmitter responds
slowly or does not
respond to response
test.

• Unable to 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 transmitter wiring
is disconnected or
misconnected.

• The transmitter’s zero
reading is low enough
to cause a fail
condition.

• The transmitter is
malfunctioning.

• The calibration cylinder
is low, out-dated, or
defective.

• The calibration gas
flow rate is too low.

• The calibration gas is
not an appr opriate
concentration.

• The transmitter is
malfunctioning.

1. Verify that the transmitter wiring is
correct and secure.

2. Calibrate the transm itt er.

3. If the fail condition continues, replace
the detector.

4. If the fail condition continues, contact
RKI for further instruction.

1. Verify that the calibration cylinder
contains an adequate supply of a
fresh test sample.

2. Verify that the regulator used for
calibration is a 0.5 LPM regulator.

3. Verify that the calibration gas
concentration is appropriate for the
transmitter. The concentration should
be in the detection range, preferably
about half of the detection range.

4. If the calibration/response difficulties
continue, replace the detector.

5. If the calibration/response difficulties
continue, contact RKI for further
instruction.

Replacing Components of the Combustible Gas Transmitter

This section includes procedures to replace the combustible gas detector and amplifier.

Replacing the IR LEL Detector

1. Turn off the controller.

2. Turn off or unplug pow er to the co ntroller.

3. Remove the junction box cover.

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

65-2394RK Combustible Gas Transm itter • 11

hub. If necessary for en vironm e ntal 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 3 on page 7 of this manual.

Table 3:Reconnecting the Combustible Gas

Detector to the Amplifier

Detector Lead Detector Terminal Strip

Red LEL “R”

White LEL “W”

Green LEL “G”

Black LEL “B”

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 stab ilizing 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.

CAUTION: Allow the replacement detector to warm up for 5 minutes before you co ntinue with

the next step.

13. Calibrate the transmitter as described in “Calibration” on page 14 of this manual.

Replacing the Amplifier

1. Turn off the controller.

2. Turn off or unplug pow er to the co ntroller.

3. Remove the junction box cover.

4. Unplug the detector terminal strip and controller terminal strip from their sockets.
You may leave the wires connected to the terminal strips.

5. Unscrew and remove the screw with the flat and lock washers that secures the
amplifier to the junction box.

6. Remove the old amplifier.

7. Place the new amplifier in the same position as the old amplifier. A foam gasket that
orients the amplifier and keeps it from rotating is installed on the bottom of the
amplifier. Make sure the amplifier is seated flat in the junction box.

8. Install the new amplifier in to the junction box with the screw, lock washer, and flat
washer you removed in Step 5 above.

12 • 65-2394RK Combustible Gas Transmitter

9. Install the detector and controller terminals strips into their sockets on the new
amplifier as shown in Figure 3 on page 7 of this manual. If controller leads or detector
leads were removed d uring this procedure, refer to Table 4 and Table 5 b elow.

Table 4:Reconnecting the Amplifier

to the Controller

Amplifier Controller

Terminal Strip

PWR/SIG “-” - (DC -)
PWR/SIG “S” S (4 - 20 mA In)
PWR/SIG “+” + 24V

Table 5:Reconnecting the LEL

Detector to the Amplifier

Amplifier Detector

T erminal Strip

DETECTOR “R” RED
DETECTOR “W” WHT
DETECTOR “G” GREEN

DETECTOR “B” BLK

Controller

Transm itte r Terminal

Strip (typical)

Detector Lead

NOTE: When a transmitter is first powered up with a new amplifier, the initial output

may be either high or below zero depending on the setting of the zero pot. Be
sure to make arrangements so that this does not cause unwanted alarms.

10. Turn on power to the controller.

11. 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 stab ilizing 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.

12. Allow the transmitter to warm-up for 5 minutes.

13. Calibrate the transmitter as described in “Calibration” on page 14 of this manual.

65-2394RK Combustible Gas Transm itter • 13

Calibration Frequency

Although there is no particular calibration frequency that is correct for all applications, a
calibration frequency of every 6 months is adequate for most infrared combustible gas
transmitter applications. Unless experience in a particular application dictates otherwise,
RKI Instruments, Inc. recommends a calibration frequency of every 6 months.

If an application is not very demanding, for example detection in a clean, temperature
controlled environment where calibration adjustments are minimal at calibration, then a
calibration frequency of every 9 to 12 months is adequate.

If an application is very demanding, for example if the environment is not well controlled,
then more frequent calibration than every 6 months may be necessary.

Calibration

This section describes how to calibrate the combustible gas transmitter. It includes
procedures to prepare for calibration, set the zero reading, set the response reading, and
return to normal operation.

W ARNING: The controller is not an active gas monitoring device during the calibration

procedure.

NOTE: The following procedure assumes the use of a calibration kit which includes a

calibration gas cylinder, a 0.5 LPM fixed flow regulator with an on/off knob, a
calibration cup for the detector, and a short piece of sample tubing to connect the
regulator to the calibration cup.

Prepari ng for Ca libration

1. Unscrew and remove the junction box cover.

2. Set a voltmeter to measure in the millivolt (mV) range.

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. Use the following formula to determine the correct test points output for the
calibrating sample.

Output (mV) = (calibrating sample/fullscale) X 400 + 100

For example, with a calibrating sample of 50 %LEL and a fullscale setting of
100 %LEL, the correct output is 300 mV.

300(mV) = (50/100) X 400 +100

5. Screw the calibration cup onto the detector housing.

6. Place the controller into its calibration mode or disable external alarms.

NOTE: Calibrating the combustible gas transmitter may cause alarms. Be sure to put the

controller into its calibration mode or disable external alarms before continuing.

14 • 65-2394RK Combustible Gas Transmitter

Setting the Zero Reading

NOTE: If you can verify that the combustible gas transmitter is in a fresh air

environment, you do not need to apply zero air to the detector before adjusting
the zero reading.

1. Screw the regulator into the zero air calibration cylinder.

2. Use the calibration kit sample tubing to connect the regulator to the calibration cup.

3. Turn the regulator’s on /off knob counterclockwise to open the regulator.

4. Allow the gas to flow for one minute and verify a reading of 100 mV (±2 mV). If
necessary, use the zero pot on the amplifier to adjust the reading to 100 mV (±2 mV).

5. Turn the regulator’s on/off knob clockwise to close the regulator.

6. Unscrew the regulator from the zero air calibration cylinder.

7. Leave the sample tubing connected to the regulator and the calibration cup.

Setting the Response Reading

1. Screw the regulator into the calibration cylinder. Verify that the calibration gas is
representative of the transmitter’s target gas.

2. Turn the regulator’s on /off knob counterclockwise to open the regulator.

3. Allow the calibration gas to flow for one minute and verify that the reading matches
the response reading (±2 mV) you determined ea rlier. If necessary, use the span pot on
the amplifier to adjust the reading to match the correct response reading.

4. Turn the regulator’s on/off knob clockwise to close the regulator.

5. Unscrew the regulator from the calibration cylind er.

Returning to Normal Operation

1. Remove the voltmeter leads from the amplifier test poin ts.

2. Unscrew the calibration cup from the detector.

NOTE: For convenience, leave the regulator and calibration cup connected by the

sample tubing.

3. Secure the junction box cover to the junction box.

4. When the controller display reading falls below th e alarm setpoints, return the
controller to normal operation.

5. Verify that the controller display reading decreases and stabilizes at 0 %LEL.

6. Store the components of the calibration kit in a safe and convenient place.

65-2394RK Combustible Gas Transm itter • 15

Parts List

Table 6 lists replacement parts and accessories for the combustible gas transmitter.

Table 6:Parts List

Part Number Description

06-1248RK Sample tubing (3/16 in. x 5/16 in.; specify length when ordering)
18-0400RK-01 Junction box with spacers
57-1053RK Amplifier with gasket (specify detector part number when ordering)
61-0190RK-CH4 Methane infrared LEL detector
61-0190RK-HC HC infrared LEL detector (calibrated to propane)
65-2394RK-CH4 Methane transmitter (includes detector, junction box, and amplifier)
65-2394RK-HC Propane transmitter (includes detector, junction box, and amplifier)
71-0181RK 65-2394RK Combustible Gas Transmitter Operator’s Manual (this document)
81-0004RK-01 Steel calibration cylinder, 50% LEL propane in air, 34-liter
81-0012RK-01 Steel calibration cylinder, 50% LEL methane in air, 34-liter
81-0076RK-01 Steel calibration cylinder, zero emission air, 34-liter
81-1050RK Regulator , 0.5 liter/minute; with pressure gauge and flow control knob, for 17

81-1103RK Calibration cup
82-0006RK Pot adjust screwdriver, for calibration
81-F002RK-LV Calibration kit, includes regulator, sample tubing, calibration cup, and 34 liter

81-F006RK-LV Calibration kit, includes regulator, sample tubing, calibration cup, and 34 liter

liter and 34 liter steel calibration cylinders

50 %LEL methane in air steel calibration cylinder

50 %LEL propane in air steel calibration cylinder

16 • 65-2394RK Combustible Gas Transmitter