GX-3R Pro with TIIS Approval (now available) | RKI

GX-3R Pro with TIIS Approval (now available)

Confined Space 5 Gas Monitor


  • Smallest & lightest detector
  • Detect up to 5 gases simultaneously
    Confined Space: LEL, O2, H2S, CO
    – Toxics/IR Sensors: HCN, NH3, NO2, PH3, SO2, and CO2
    – H2 Compensated CO sensor available
  • Simple 2-button operation
  • Bluetooth communication with iOS & Android App
  • 3 user adjustable alarm levels
  • Panic Alarm & Man Down Alarm
  • Large full dot, auto-backlit display with auto-rotation
  • Field replaceable sensors & filters
  • Water and dust resistant design, IP66/68
  • 3 Year Warranty*
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GX-3R Pro Five Gas Monitor callouts

The GX-3R Pro is the world’s smallest 5-gas monitor weighing only
4.58 ounces and fits in the palm of your hand (2.9” W x 2.6” H x 1.06” D).
It simultaneously monitors and displays 5 different gases. In addition to monitoring standard confined space gases, LEL, O2, CO, & H2S, the
GX-3R Pro has a 5th channel where you can add infrared or toxic gas sensors (Hydrogen Cyanide (HCN) and Nitrogen Dioxide (NO2) sensors are currently available for the GX-3R Pro). Two of the four sensor slots have interchangeable sensors providing flexible configurations, which can easily be changed in the field.

RKI is pleased to announce the availability of  These 2 sensors are in stock and are the latest in toxic gas options added to the line of GX-3R Pro sensors.

The GX-3R Pro comes equipped with Bluetooth wireless communication, man-down alarm, the choice of alkaline or rechargeable power supply, and a 3 year warranty. The Lithium-ion battery pack will operate for 25 hours and will fully charge in 3 hours.

The GX-3R Pro utilizes Bluetooth communication to display direct gas readings from the instrument to a phone app, which is available free on either iOS or Android phones. Automatic notifications can be programmed to send text or email messages if there is an alarm event from the
GX-3R Pro.

Safety supervisors will appreciate the non-compliance indicator. The instrument flashes it’s 3 LED lights every 30 seconds in the following conditions; if the instrument has not been bump tested, or if calibration is due, or if there was a gas alarm event. The 3 LED lights will continue to flash once every 30 seconds until the non-compliance condition has been resolved. The 30 second interval is adjustable.

* 3 year warranty on material and workmanship including sensors (1 year for Ammonia sensor)

FAQ about TIIS vs ATEX/CSA certification PDF Download Link

FAQ about TIIS vs ATEX/CSA certification

Are there differences in product specifications between the ATEX/CSA and TIIS versions of the GX-3R?
No. Both versions are identical in every aspect except for the certification labels.

Is TIIS intrinsically safe for Class 1, Division 1 explosion proof environments?
Yes. The TIIS-certified GX-3R & GX-3R Pro are subjected to the same IEC safety standards as the ATEX/CSA GX-3R & GX-3R Pro.

Can I use a TIIS certified GX-3R in North America?
Yes. The TIIS versions are identical to the ATEX/CSA versions in every aspect and pass the same safety standards for the certification labels as the ATEX/CSA.

Why do I have to submit the Acknowledgement Form?
It is solely for RKI’s internal records that the end user acknowledges their new order is the GX-3R with the TIIS certification. The Acknowledgement Form is not a waiver or release form. Link to Acknowledgement Form

If I accept the Acknowledgement Form, am I liable in some way?
No. If there are any product failures on the GX-3R with TIIS certification, RKI takes full responsibility just as it would with the CSA versions. The GX-3R with TIIS certification is covered under warranty just like any of RKI’s other product lines. Link to Acknowledgement Form

Are the part numbers different?
The part # are the same as the existing GX-3R part numbers and just have a “-T” added to the end.

For example:
72-RA-C is the part number for a 4-gas GX-3R (ATEX/CSA) with Li-Ion battery pack.
72-RA-C-T would be the part number for the 4-gas GX-3R (TIIS) with Li-Ion battery pack.

Are the prices the same?

How soon can the GX-3R with TIIS certification be shipped?
Once you have completed the acknowledgement form and requested your order change with customer service, you will receive a confirmation email with your new scheduled ship date within the day.

Can I revise my current GX-3R (ATEX/CSA) order to the TIIS version?
Yes, absolutely. Contact RKI’s customer service with the purchase order number you would like to revise and customer service will send a confirming email with the new ship date.

Does OSHA approve the TIIS certification?
No, but they do not approve the ATEX/CSA certification either. OSHA does not approve any Intrinsically safe certification body. They simply recommend the use of an instrument which has a third-party verification performed.

Can I use the label from an older GX-3R and put it on the TIIS approved GX-3R?
No. The certification labels can only be applied by the manufacturer.

Are TIIS versions of the GX-3R in English?
Yes. The TIIS and CSA/ATEX versions are identical in every aspect except for the certification labels.

When will the hold on the ATEX/CSA certification end?
The hold is expected to be released in January or 2024.


  • Personal monitoring
  • Confined spaces
  • Refineries/petrochemical
  • Utilities
  • Oil and Gas
  • Water/Wastewater
  • Fire Services
  • Construction


Detectable Gases

Gas Measuring Range
Preset Alarms
Sensor Slot 1: Carbon Monoxide (CO) & Hydrogen sulfide (H2S) *Interchangeable
H2S / CO Dual EC 0 ~ 2000 ppm
(1 ppm)
± 5% of reading
or ± 5 ppm CO
A1: 25 ppm│ A2: 50 ppm │ A3:1200 ppm│TWA: 25 ppm │ STEL: 200 ppm
0 ~ 200.0 ppm
(0.1 ppm)
± 5% of reading
or ± 2 ppm H2S
A1: 5 ppm│ A2: 30 ppm │ A3: 100 ppm│TWA: 1.0 ppm │ STEL: 5.0 ppm
EC 0 ~ 200.0 ppm
(0.1 ppm)
± 5% of reading
or ± 2 ppm H2S
A1: 5 ppm│ A2: 30 ppm │ A3: 100 ppm│TWA: 1.0 ppm │ STEL: 5.0 ppm
H2 Compensated
EC 0 ~ 2,000 ppm ± 5% of reading
or ± 2 ppm CO
A1: 25 ppm│ A2: 50 ppm │ A3: 1200 ppm│TWA: 25 ppm │ STEL: 200 ppm
Sensor Slot 2: Combustibles (Methane as standard)
CH4 / HC Catalytic 0 ~ LEL (1% LEL) ± 5% of reading
or ± 2 % LEL
1st: 10% LEL │ 2nd: 25% LEL │ 3rd: 50% LEL │ Over:100% LEL
Sensor Slot 3: Oxygen (O2)
O2 EC 0 ~ 40.0% Vol.
± 0.5% O2 Low 1: 19.5%│ Low 2: 18.0% │High: 23.5%│ Over: 40.0%
Sensor Slot 4: Toxics & CO2 *Interchangeable
HCN EC 0 ~ 30.0 ppm
(0.1 ppm)
± 10% of reading
or ± 5 % of full scale
A1: 5.0 ppm│ A2: 10.00 ppm │ A3: 30.00 ppm│ TWA: 4.7 ppm
│ STEL: 10 ppm
NH3 0 ~ 400.0 ppm
(0.5 ppm)
A1: 25.0 ppm │ STEL: 1.0 ppm│
A2: 35.0 ppm│ TWA: 0.30 ppm│A3: 300.0 ppm
NO2 0 ~ 20.00 ppm
(0.05 ppm)
A1: 2.00 ppm│ A2: 4.00 ppm │ A3: 20.00 ppm│ TWA: 0.20 ppm │ STEL: 1.00 ppm
PH3 0 ~ 20.00 ppm (0.01 ppm) A1: 0.30 ppm │ STEL: 1.0 ppm │ A2: 0.60 ppm │ TWA: 0.30 ppm │ A3: 0.60 ppm
SO2 0 ~ 100.0 ppm
(0.05 ppm)
A1: 2 ppm│ A2: 5 ppm │ A3: 100 ppm│ TWA: 0.25 ppm │ STEL: 0.25ppm
CO2 % IR 0 ~ 10.0% Vol.
± 5% of reading
or ± 2 ppm
A1: 0.50% Vol.│ A2: 3.00% Vol. │ A3: 4.00% Vol.│ TWA: 0.50% Vol. │ STEL: 3.00% Vol.
CO2 ppm 0 ~ 10,000 ppm
(20 ppm)
A1: 5,000 ppm│ A2: N/A │ TWA: N/A│STEL: N/A

Common Specifications

Sampling Method Diffusion sampling standard
(hand aspirator or clip-on motorized pump optional)
Display Full dot LCD with Autobacklight
and Autorotation
Alarm Types Gas Alarm Trouble Alarm
  • 2 increasing alarms
  • STEL
  • TWA
  • Over scale alarm
  • O2 decreasing/
  • Sensor disconnection
  • Low battery
  • Circuit error
  • Calibration range error
  • Cal or bump due alarm
• Man Down Alarm
• Panic Alarm
Display of Alarm Gas Alarm Trouble Alarm
  • Flashing LED’s
  • Continuous buzzer (100 db @ 30cm)
  • Flashing gas value
  • Vibration
  • Flashing LED’s
  • Intermittent buzzer (95 db @ 30cm)
  • Display of error message
Operating Temp. & Humidity -20°C ~ +50°C
[ -4°F ~ +122°F ]
10 to 90% RH, non-condensing (continuous environment)
-40°C ~ +60°C
[ -40°F ~ +140°F ]
0 to 95% RH, non-condensing
(temporary environment)
Response Time Within 30 seconds (T90)
Power Source Config Li-ion Alkaline
4-gas + EC 25 hours 16 hours
4-gas + EC with Bluetooth 23 hours 14 hours
4-gas + IR 16 hours 7 hours
4-gas + IR with Bluetooth 15 hours 6 hours
Dimension & Weight 2.9” W x 2.6” H x 1.06” D
(Approx. 73 W x 65 H x 26 D mm), 4.58oz (with rubber boot)
Case Material Dust and water resistant to IP-66/68 (2m,1h) approval. Drop height 23 ft
Bluetooth Communication BLE: with iOS and Android phone app: RK Link
Datalogging Logs user ID, station ID, Calibration & Bump Test history, Alarm Events &
Alarm Trends
Standard Accessories Alligator clip, protective rubber boot, charger, calibration adapter
Optional Accessories
  • Padded carrying case
  • RP-3R Attachable sampling pump with 4” rubber nipple, 10’ hose and probe (up to 40’ hose available)
  • USB to IrDA downloading cable for datalogger
  • SDM-3R calibration station
  • Hand aspirator
Safety Design / Approvals TIIS

Three years material and workmanship including sensors (1 year for Ammonia sensor)


GX-3R Pro Spare Parts

Part # Description
07-6054 Sensor gasket, GX-3R Pro
07-6055 Sensor case o-ring, GX-3R Pro
10-1086 Screw with flat and lock washers, M2 x 4 phillips
10-1087 Screw for GX-3R Pro sensor cap & battery pack
13-0112RK Wrist strap
13-0124 Alligator Clip with installation screws
13-0125 Belt Clip with installation screws
20-0335 Rubber boot for GX-3R Pro
21-1950 LCD protective film for GX-3R/GX-3R Pro
21-1960 Bottom cover (sensor cap), GX-3R Pro
21-1961 Sensor retainer, GX-3R Pro
29-0700 Sensor case label for GX-3R Pro, CO/H2S / LEL /O2 /Toxic
33-0184-10 Sensor dust filters with internal gasket for GX-3R Pro, 10-pack
33-0554 Buzzer protection cover for GX-3R Pro
33-7130 Scrubber disk filter for H2S/CO sensor 5-pack
33-7131 Scrubber disk filter for LEL sensor, 5-pack
33-7132 Scrubber disk filter, charcoal, for CO & H2 comp CO sensor, GX-3R/GX-3R Pro, 5-pack
33-7133 Humidity filter disk for H2S sensor, GX-3R/GX-3R Pro, 5-pack
33-7134 H2S scrubber disk for SO2 sensor, GX-3R Pro, 5-pack
49-1625 Li-Ion battery pack for GX-3R Pro
49-1626 Alkaline battery pack for GX-3R Pro
ESR-A13D-SO2 Sensor, SO2 for GX-3R Pro
ESR-A13I-H2S Sensor, H2S for GX-3R/GX-3R Pro
ESR-A13P-CO Sensor, CO, GX-3R/3R Pro
ESR-X13P-OXY Sensor, O2 for GX-3R/GX-3R Pro
ESR-A1CP-CO-H Sensor, CO with H2 compensated for GX-3R/GX-3R Pro
ESR-A1DP-COHS Sensor, H2S/CO combo for GX-3R/GX-3R Pro
NCR-6309 Sensor, LEL for GX-3R/GX-3R Pro
IRR-0409 Sensor, CO2, 0-10% volume for GX-3R Pro
IRR-0433 Sensor, CO2, 0-10,000 ppm for GX-3R Pro
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