RKI Instruments T3A User manual

RKI Instruments, Inc.
www.rkiinstruments.com
AirLink T3A
Operator’s Manual
Part Number: 71-0536
Revision: P6
Released: 9/26/22

2• AirLink T3A Operator’s Manual
WARNING
Read and understand this instruction manual before operating
detector. Improper use of the detector could result in bodily harm or
death.
Periodic calibration and maintenance of the detector is essential for
proper operation and correct readings. Please calibrate and maintain
this detector regularly! Frequency of calibration depends upon the
type of use you have and the sensor types. For most applications,
typical calibration frequencies are between 3 and 6 months but can be
more often or less often based on your usage.

AirLink T3A 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• AirLink T3A Operator’s Manual
Caution Statements
WARNING: EXPLOSION HAZARD - SUBSTITUTION OF COMPONENTS MAY IMPAIR
SUITABILITY FOR CLASS I, DIVISION 1, or equivalent as stated in user
manual.
AVERTISSEMENT: RISQUE D'EXPLOSION-LA SUBSTITUTION DE COMPOSANTS
PEUT RENDURE CE MATERIEL INACCEPTABLE POUR LES
EMPLACEMENTS DE CLASSE I, DIVISION I.
CAUTION: For safety reasons, this equipment must be operated and serviced by qualified
personnel only. Read and understand the instruction manual completely before
operating or servicing.
ATTENTION: POUR DES RAISONS DE SECURITE, CET ÉQUIPEMENT DOIT ETRE
UTILISE ENTRETENU ET REPARER UNIQUEMENT PAR UN PERSONNEL
QUALIFIE. ETUDIER LE MANUEL D' INSTRUCTIONS EN ENTIER AVANT
D' UTILISER, D' ENTERETENIR OU DE RÉPARER L' ÉQUIPEMENT.
CAUTION: THIS AREA MUST BE FREE OF FLAMMABLE GASES DURING CALIBRATION.
ATTENTION: CETTE ZONE DOIT ETRE EXEMPTE DE GAZ INFLAMMABLES PENDANT
L'ETALONNAGE.
CAUTION: TO PREVENT IGNITION OF EXPLOSIVE ATMOSPHERES, remove from
explosive atmosphere BEFORE SERVICING.
WARNING: A conduit seal must be used within 18 inches of the enclosure wall to comply with
the hazardous location rating of this product.
Danger Statements
DANGER: The RKI Instruments Inc. AirLink T3A is an ambient air Hazardous gas sensor
assembly and only monitors in the immediate vicinity of the sensor housing. A site survey is
required in order to determine the best placement and quantity of sensor assemblies. Improper
installation can lead to an undetectable gas leak which could result in personal injury or loss of
life.

AirLink T3A Operator’s Manual • 5
Table of Contents
Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
External Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Internal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Exploded Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Remote-Mounted Kit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Mounting the AirLink T3A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Remote-Mounted Kit Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Wiring Power and 4-20 mA Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Connecting RS-485 Modbus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Connecting Relays/Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Connecting the Fault Terminal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Closing the Enclosure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Start Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
Normal Operating Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Manual Reset for Activated Latching Alarms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Magnetic Buttons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Powering the Device. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Faults. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Accessing Menus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Product Settings and Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Entering the Product Settings and Configuration Menu. . . . . . . . . . . . . . . . . . . . . . . . . . 32
Alarm Test. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Network ID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

6• AirLink T3A Operator’s Manual
System Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Zero/Calibration Timer Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Unit Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Background Setting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Latching and Auto Resetting Relay Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Relay Fail-Safe Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Fault Terminal Fail-Safe Setting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Calibration Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Modbus Address Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Modbus Baud Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
4-20 mA Offset Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Display Screen Contrast Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Return to Factory Default Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Reset Zero & Calibration Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Operation Settings and Calibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46
Zeroing the Sensor (20.9% for O2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Calibrating the Sensor (Manual Cal) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Calibrating the Sensor (Auto Cal) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Sensor Alarm Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Sensor Radio Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Replacing the Desiccant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Replacing Catalytic Type Sensors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Replacing Non-Catalytic Type Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Replacing the Fuse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65
Appendix A: 4-20 mA Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69
Appendix B: Modbus Communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71
Appendix C: Modbus Register Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73

AirLink T3A Operator’s Manual • 7
Overview
The RKI Instruments, Inc. AirLink T3A explosion-proof ambient air hazardous gas detector is
designed to detect a wide range of toxic gases in potentially hazardous environments. This
product is QPS certified as Class I, Division 1, Groups B, C, and D and rated for Zone 1, Group
IIB. The AirLink T3A features non-intrusive magnetic switches that allow for complete system
configuration, regular calibration, and product maintenance to be performed in the field, without
opening the enclosure and breaking the seal of the enclosure, thereby compromising the
explosion-proof rating of the device. Non-intrusive interface with the AirLink T3A is made
possible by use of the magnetic tool included in the purchase of the device.
In this manual, the instructions reference the use of push-buttons, located on the front panel of the
device. In certain environments, the activation of the non-intrusive magnetic switches, through
the use of the magnetic tool, will replace the directive of the button-press actions. To apply the
magnetic tool, hold the tool to the side of the device enclosure adjacent to the push-button that
you wish to activate. When the magnetic switch is toggled, an on-screen indicator will appear on
the display screen, signifying that a connection was made.
The AirLink T3A display screen will always show the present concentration of gas being detected
by the sensor assembly.
This document is an operation manual containing diagrams and step-by-step instructions for the
proper and safe installation, start-up, configuration, normal operation, and product maintenance
of the AirLink T3A.
NOTE: This document should be read in its entirety before the initial operation of the product.

8• Specifications AirLink T3A Operator’s Manual
Specifications
Table 1 lists specifications for the AirLink T3A.
Table 1: Specifications
Target Gas Detection
Range
Increments Haz. Loc. Alarm Points
(1 / 2 / 3 / 4)*
Ammonia (NH3) 0-100 ppm 1 ppm Cl. 1 Div. 2 12 / 25 / 50 / 100 ppm
0-200 ppm 25 / 35 / 50 / 200 ppm
0-300 ppm 25 / 35 / 50 / 300 ppm
0-500 ppm 35 / 300 / 300 / 500 ppm
0-1000 ppm 35 / 300 / 300 / 1000 ppm
Arsine (AsH3) 0-1.00 ppm 0.01 ppm 0.2 / 0.5 / 1.0 / 1.0 ppm
Carbon Dioxide (CO2) 0-5000 ppm 1 ppm Cl. 1 Div. 1 2500 / 5000 / 5000 / 5000 ppm
0-5.0% volume 0.1% volume 0.5 / 3.0 / 5.0 / 5.0%
volume
Carbon Monoxide (CO) 0-500 ppm 1 ppm 25 / 50 / 100 / 500 ppm
0-1000 ppm 1000 / 1000 / 1000 / 1000 ppm
Chlorine (Cl2) 0-10.0 ppm 0.1 ppm Cl. 1 Div. 2 1 / 3 / 5 / 10 ppm
Chlorine Dioxide (ClO2) 0-1.00 ppm 0.01 ppm 0.1 / 0.3 / 0.3 / 1.0 ppm
Combustible Gas 0-100% LEL 1% LEL Cl. 1 Div. 1 10 / 20 / 50 / 100% LEL
0-100% volume 1% volume 100 / 100 / 100 / 100%
Ethylene Oxide (EtO) 0-10.00 ppm 0.01 ppm Cl. 1 Div. 2 1 / 3 / 5 / 10 ppm
Formaldehyde (CH2O) 0-10.00 ppm 0.5 / 2 / 5 / 10 ppm
Hydrogen (H2) 0-100% LEL 1% LEL Cl. 1 Div. 1 10 / 20 / 50 / 100% LEL
Hydrogen Chloride
(HCl)
0-20 ppm 1 ppm Cl. 1 Div. 2 5 / 10 / 10 / 20 ppm
0-30 ppm 5 / 10 / 10 / 30 ppm
0-100 ppm 5 / 10 / 30 / 100 ppm
Hydrogen Cyanide
(HCn)
0-15 ppm Cl. 1 Div. 1 5 / 10 / 15 / 30 ppm
0-50 ppm 5 / 10 / 15 / 50 ppm
Hydrogen Fluoride (HF) 0-10.0 ppm 0.1 ppm Cl. 1 Div. 2 3 / 6 / 6 / 10 ppm
Hydrogen Sulfide (H2S) 0-10.0 ppm 1 ppm Cl. 1 Div. 1 1 / 5 / 10 / 10 ppm
0-25 ppm 5 / 10 / 10 / 25 ppm
0-50 ppm 5 / 10 / 10 / 50 ppm
0-100 ppm 10 / 50 / 75 / 100 ppm
0-500 ppm 100 / 200 / 200 / 500 ppm
0-2000 ppm 100 / 200 / 200 / 2000 ppm

AirLink T3A Operator’s Manual Specifications • 9
Nitric Oxide (NO) 0-250 ppm 1 ppm Cl. 1 Div. 2 25 / 50 / 100 / 250 ppm
Nitrogen Dioxide (NO2) 0-20 ppm 5 / 10 / 10 / 20 ppm
Oxygen (O2) 0-25.0% volume 0.1% volume Cl. 1 Div. 1 19.5% dec. / 23.5% inc. / 17.0%
dec. / 25.0% inc.
Ozone (O3) 0-5.0 ppm 0.1 ppm Cl. 1 Div. 2 1 / 3 / 5 / 5 ppm
0-100 ppm 1 ppm 10 / 15 / 15 / 100 ppm
Phosphine (PH3) 0-5.0 ppm 0.1 ppm Cl. 1 Div. 1 0.3 / 1.0 / 1.0 / 5.0 ppm
Sulfur Dioxide (SO2) 0-20 ppm 1 ppm 2 / 5 / 5 / 20 ppm
* Alarms 3 and 4 are only programmable at a controller and do not affect operation of the AirLink T3A.
Sampling Method Diffusion
Enclosure Ratings • Explosion/Flame-Proof
•IP-51
Junction Box
Hazardous Location
Certification
Class I, Division 1, Groups B, C, D
Ex db IIB Gb
Class I, Zone 1, AEx db IIB Gb
Tamb -40°C to +60°C
Sensor Housing
Hazardous Location
Certification
Class I, Division 1 (or Division 2), Groups B, C, D
Ex db IIB Gb
Tamb -40°C to +60°C
NOTE: Certification only applies to some gases.
Toxic gases not certified for Div. 1 locations are
suitable for Div. 2 applications but have no third
party approval.
Operating Voltage 12 - 35 VDC
Current Draw 250 mA max
Operating
Temperature Range
-40°C to +54°C (-40°F to +129°F)
Humidity Range 0 - 98% relative humidity, non-condensing
Signal Output • 4 to 20 mA (3-wire)
• RS-485 Modbus RTU
• Wireless radio (optional)
Max Cable Length
for Remote-
Mounted Antenna
100 feet
Relay Contact
Ratings
• 3A at 24 VDC, 115 VAC, and 250 VAC
• each relay terminal protected by a 4A fuse
Table 1: Specifications
Target Gas Detection
Range
Increments Haz. Loc. Alarm Points
(1 / 2 / 3 / 4)*

10 • Specifications AirLink T3A Operator’s Manual
WARNING: When using the AirLink T3A, you must follow the instructions and warnings in
this manual to assure proper and safe operation of the AirLink T3A and to
minimize the risk of personal injury. Be sure to maintain and periodically
calibrate the AirLink T3A as described in this manual.
Enclosure Material Aluminum
Sensor Housing
Material
303 Stainless steel
Max Cable Length
for Remote-
Mounted Sensor Kit
• Electrochemical (EC): 250 feet
• Infrared (IR): 40 feet
• Catalytic: 15 feet
Dimensions 5.5” D x 6” W x 7” H
Weight 6 lbs.
Standard
Accessories
• Rain guard
• Magnet

AirLink T3A Operator’s Manual External Description • 11
External Description
Figure 1: AirLink T3A External Component Location
1MENU button 8Sensor housing assembly
2Front panel thumbscrew 9Rain guard
3Enclosure 10 Magnetic tool
4explosion-proof plug 11 Alarm 1 LED
5SUB button 12 ADD button
6Mounting hole 13 Enclosure lid locking screw
7Alarm 2 LED 14 Display screen
NOTE: The AirLink T3A’s conduit hubs are 3/4 NPT.

12 • Internal Description AirLink T3A Operator’s Manual
Internal Description
Figure 2: Internal Component Location
1RS-485 Modbus terminal block 5Sensor housing socket
2Fault terminal block 6Antenna fitting connector
3Power input/4-20 mA output
terminal block 7Relay 1 terminal block (if relays installed)
4Radio module 8Relay 2 terminal block (if relays installed)

AirLink T3A Operator’s Manual Exploded Drawing • 13
Exploded Drawing
Figure 3: Exploded Diagram
1Enclosure lid 7Sensor housing base
2Internal system 8Sensor element
3Antenna fitting plug 9Rain guard
4Enclosure body 10 (with flame arrestor for Class 1 Div. 1 assemblies;
without flame arrestor for Class 1 Div. 2 assemblies)
5Antenna fitting 11 Analog sensor board
6900 MHz or 2.4 GHz antenna 12 Sensor housing plug

14 • Remote-Mounted Kit AirLink T3A Operator’s Manual
Remote-Mounted Kit
A remote-mounted sensor kit can be ordered if the sensor needs to be somewhere that is not
conveniently accessible for viewing the display screen.
The kit includes a second junction box on a cable with a cable bushing/cable gland. The cable can
be ordered in 1-foot increments with maximum cable lengths listed below.
The cable and cable bushing/cable gland are not explosion-proof. If the assembly is installed in a
classified location, the cable bushing must be removed and replaced with explosion-proof
conduit. You must meet local electrical codes and use appropriate construction technique to
maintain the explosion-proof classification of the assembly.
Installation
This section describes procedures to mount the AirLink T3A in the monitoring environment and
wire the AirLink T3A.
Mounting the AirLink T3A
1. Consider the following when you select the mounting site.
• Select a site where the AirLink T3A 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 that is representative of the monitoring environment and where the target gas
is likely to accumulate or where it is most likely to leak. The AirLink T3A should not be
installed near an entrance, air intake, or exhaust point.
• The sensor must point down.
• Avoid installing the AirLink T3A in a location where airborne particles could cover or
coat the sensor.
NOTE: These guidelines are ONLY intended as a general directive for the
placement of the AirLink T3A. This information should NOT serve as a
complete list when considering all potential parameters for the proper
location of the unit. It is STRONGLY advised that a third party Certified
Industrial Hygienist, or other Certified Safety Professional, conduct a site
survey and annotate the location and quantity of detection devices that
should be installed for EVERY installation of EVERY site.
Sensor Type Max Cable
Length
Electrochemical (EC) 250 feet
Infrared (IR) 40 feet
Catalytic 15 feet

AirLink T3A Operator’s Manual Installation • 15
2. Select a mounting location and installation hardware. Mounting to a concrete or steel structure
is recommended to minimize vibration and moisture. Use a maximum 1/4”-20 bolt or 1/4”
diameter screw, flat washers, Grade 5 material, and corrosion protection like paint,
galvanization, or zinc plating.
Figure 4: AirLink T3A Dimensions
3. For a remote-mounted kit, install the detector junction box at the monitoring environment
using techniques appropriate for the mounting area’s classification and for the local electrical
code. The cable and cable bushing/cable gland sent with the assembly are not explosion-
proof.
WARNING: If installed in a classified area, use appropriate construction technique to
maintain the explosion-proof classification of the assembly.
900 MHz Antenna
5.5
13.5
Ø 0.25
16.7
5.4
9.2
2.4 GHz Antenna

16 • Installation AirLink T3A Operator’s Manual
Figure 5: Remote-Mounted Kit’s Detector Junction Box Dimensions
4.64
2.70
9.95

AirLink T3A Operator’s Manual Installation • 17
Remote-Mounted Kit Wiring
The remote-mounted kit generally comes prewired but if it becomes disconnected, follow these
steps to reconnect it.
CAUTION: The internal components can be static sensitive. Use caution when opening the
enclosure and handling internal components.
CAUTION: Make sure the power source is off before beginning the wiring procedure.
CAUTION: DO NOT use any metal objects or tools to remove the terminal board from the
internal system.
1. Unscrew each enclosure lid and set it aside.
2. At the amplifier junction box, grab the thumbscrews and gently lift the internal system out of
the enclosure. It can rest on the edge of the enclosure.
3. One end of the cable has a connector and the other has ferruled wires.
4. Feed the connector end of the cable through a 3/4 NPT conduit hub at the amplifier junction
box.
WARNING: If installed in a classified area, use appropriate construction technique to
maintain the explosion-proof classification of the assembly.
5. Plug the connector into the sensor connector socket at the amplifier junction box.
6. Feed the ferruled-wire end of the cable through a 3/4 NPT conduit hub at the detector junction
box.
WARNING: If installed in a classified area, use appropriate construction technique to
maintain the explosion-proof classification of the assembly.
7. Connect the ferruled wires to the color-coded terminals in the detector junction box.
8. Secure the detector junction box’s enclosure lid back onto the enclosure.

18 • Installation AirLink T3A Operator’s Manual
Wiring Power and 4-20 mA Output
The AirLink T3A has several basic wiring configurations, dependent upon the desired usage and
functionality intended by the end-user. All AirLink T3A units require +12 to +35 Volts of wired
DC power to operate. Data communication from the device, through either the 4-20 output or the
RS-485 Modbus connection, to an external location are optional.
CAUTION: The internal components can be static sensitive. Use caution when opening the
enclosure and handling internal components.
CAUTION: Make sure the power source is off before beginning the wiring procedure.
CAUTION: DO NOT use any metal objects or tools to remove the terminal board from the
internal system.
1. Unscrew the enclosure lid and set it aside.
2. Grab the thumbscrews and gently lift the internal system out of the enclosure. It can rest on
the edge of the enclosure.
NOTE: Disconnecting the sensor connector plug from the sensor housing will allow
for the complete removal of the internal system from the device enclosure.
Disconnecting the internal system may provide ease in accessing the control
board terminals for wiring. Reconnect the sensor connector plug before
reinstalling the internal system.
WARNING: Use appropriate construction technique to maintain the explosion-proof
classification of the assembly.
Table 2: AirLink T3A Terminal Block Wire Gauges
Terminal Block Wire Gauge
Power terminal Min: 26 AWG
Max: 14 AWG
Relay 1 & 2 terminal
Modbus terminal Min: 26 AWG
Max: 16 AWG
Fault terminal

AirLink T3A Operator’s Manual Installation • 19
3. Feed the power and 4-20 mA signal wires through the AirLink T3A’s 3/4 NPT power hub and
into the enclosure.
NOTE: Wiring power to the device is the ONLY requirement for the AirLink T3A to
operate. With power, the unit will function normally, indicating the presence
of toxic gas at the sensor and providing the gas level reading on the display
screen. To utilize the added functionality of the device, additional wiring is
necessary. If a controller is not used, the AirLink T3A can be powered from
any +12 to +35 VDC power supply that is capable of supplying at least 250
mA.
4. Locate the power terminal block on the control board and complete the following (see Figure
6).
• Connect the power (GRAY) wire to the VDC +terminal.
• Connect the ground (BLACK) wire to the VDC - terminal.
• Connect the signal (GREEN) wire to the 4-20 mA (S) terminal.
CAUTION: If shielded cable is used, leave the cable shield’s drain wire
disconnected and insulated at the AirLink T3A. You will connect the
opposite end of the cable’s drain wire to the controller’s chassis (earth)
ground.
5. Route the cable or wires leading from the AirLink T3A through one of the conduit hubs at the
controller housing.
CAUTION: Do not route power and AirLink T3A wiring through the same controller
conduit hub. The power cable may disrupt the transmission of the
AirLink T3A signal to the controller.
6. Connect the wires to the applicable detector terminal strip at the controller as shown in Figure
6.
Figure 6: Wiring Power and Signal Wiring

20 • Installation AirLink T3A Operator’s Manual
7. 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.
Connecting RS-485 Modbus
The AirLink T3A supports Modbus RTU over a RS-485 link.
1. If necessary, unscrew the enclosure lid and pull the internal system out by the thumbscrews.
CAUTION: Be sure power to the AirLink T3A is off before pulling out the internal
system.
2. Feed the RS-485 cable through the 3/4 NPT power hub and into the enclosure.
WARNING: Use appropriate construction technique to maintain the explosion-proof
classification of the assembly.
3. Connect the RS-485 B (BROWN) wire to the Bterminal.
4. Connect the ground (BLACK) wire to the GND terminal.
5. Connect the RS-485 A (YELLOW) wire to the Aterminal.
Table 3: AirLink T3A Terminal Block Wire Gauges
Terminal Block Wire Gauge
Power terminal Min: 26 AWG
Max: 14 AWG
Relay 1 & 2 terminal
Modbus terminal Min: 26 AWG
Max: 16 AWG
Fault terminal